rrl\i~il~ rU St~MOt~R,a FISHERIE 0000 LIBRAR Y INSTITUTE.FOR FISHERIES RESEARCH 212 Museums Annex Bldg. Ann Arbor, MI 48109 gURVEY MET-10DS Michan. Deparmn I-Cctu~ Re sources O f lev is-v i i o ill) Fisheries Management Report No. 9 January 1981 MANUAL OF FISHERIES SURVEY METHODS by James W. Merna, Chairman James C. Schneider Gaylord R. Alexander Warren D. Alward Randy L. Eshenroder MICHIGAN DEPARTMENT OF NATURAL RESOURCES FISHERIES DIVISION STEVENS T. MASON BUILDING LANSING, MICHIGAN 48909 ACKNOWLEDGMENTS Many members of the Fisheries Division contributed to this manual. We acknowledge suggestions from biologists in field, research, and staff. The manual was edited by W. C. Latta, illustrated by A. D. Sutton, and typed by M. S. McClure. ii TABLE OF CONTENTS Page I- 1 1.INTRODUCTION................... A. Perspective................... B. Surveyplanning................. C. Objectives and description of survey modules ~~~~~~~~ ~~~~~~~~ ~~~~~~~~ ~~~~~~~~ 1. Drainage and basin description 2. Limnology.................. 3. Plants and invertebrates. 4. Fish surveys............... 5. Fishery assessment........ D. Forms and information systems ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 1 1 2 2 3 3 4 4 U. SJRVEY MODULES................ A. Drainage and basin descriptions ~~~~~~~~~~~~~~ ~~~~~~~~~~~~~~ 1. 2. Lakes......... Streams a. Zones ~ ~~~ b. Stations............. c. Length.............. d. Width 0000000004 e. Depth 9'0 00'0 0a0 f. Cross section profiles g. Static water volume. h. Discharge........... i. Velocity............. j. Annual stream discharge k. Stream stage.,o........ 1. Gradient............. m. Bedtype............. n. Spawning areas *.. o. Cover............... I I r I r r II.. 1 1 1 1 4 4 4 7 10 10 10 10 11 11 11 11 12 12 B. Limnology 1. Lakes a. First level survey b. Second level survey 2. Streams.............. a. Temperature 0a b. Water chemistry iii 12 12 12 13 14 14 15 Page 3. Limnological methods.0. a. Temperature b. Dissolved oxygen0. c. Alkalinity d. Secchi disk depth e. Color..a........ f. Environmental Services 0 0~ ~ ~ ~ 0 0 0 0 0 0 a Laboratory analysis ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ 15 15 16 18 19 20 20 21 C. Plants and invertebrates................... 1. Lakes a. Macrophytes b. Chlorophyll c. Fish food. 2. Streams, a. Vegetation b. Fish food. ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~~~ ~~~~ ~~~~ ~~~~ ~ ~ ~ ~ ~~~~ ~~~, ~~~~ ~~~~ ~~~~ ~~~~ ~~~~ ~~~~ ~~~~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ D. Fish surveys. veys*.....e.e................ 1. Discussion.................. a. Catch summary.00 b. Length-frequency and length-biomass c. Fish growth....................... d. Length-weight regression.9.0.0. e. Population estimates............ 2. Procedures....o............ a. Planning.......................... b. Forms and records e......... c. Fish identification............ d. Measuring fish.............. e. Selection of-sample sites............ ~ *Index stations..................... g. Selection of gear.................. h. Duration and effort............ i. Catch per effort (CPE)............. j. Length-weight relationship.......... k. Length-frequency.................. I. Length-biomass and total biomass. m. Average length and weight........... n. Growth 0.....e.......................... o. Population estimates*.............. p. Age-frequency and survival o...... q. Production................. r. Natural history observations........ E. Fishery assessment........................ iv Rev. 1/82 ~~~~~~~ ~ r 21 21 21 21 23 23 23 24 24 25 26 27 27 28 28 29 29 29 30 30 31 32 33 33 36 37 37 39 39 40 48 48 50 50 III. cEAR 0 0 0 * 0 0 0 0 * 0 0 0 * 0 0 0 0 * 9 0 0 0 6 0 A. Trapnets 0004 s000000*0 B. Fykenets 00004 0000000aa C. Inland experimental gill nets.a............... D. Modified Great Lakes gill nets.......................... E. Seines 0 0 0 0 - 0 0 0 0 0 0 0 0 0 0 0 0 a 0 0 0 0 0 0 0 F. Toxicant sampling.................................. G. Electrofishing........................................ Re Trawl 9 0 0 6 0 0 0 0 0 0 0 0 0 0 0 0 0 0 41 a 0 a a 0 0 I. Visual observations.............................. Page III- 1 1 4 4 6 6 7 8 9 10 IVe FORMS Surveyplanning form.......................... Limnology........................... 0.... Inland Lake Management Unit--Field sheet...... Environmental Laboratory AnalysisO--Biological.0 Environmental Laboratory Analysis--Inorganics e Environmental Laboratory Analysis --Environmental Lake physical description...................... Lake area and volume analysis.................. Fish collection and Fish 3ollection (cont)......... Length-weight field data.................... Length-weight regression...................... Scale sample analysis...................... Fish growth 0 0 0 0.......a........ 0 0 0 0 0 Population estimates......................... Notes and references........a....... Lake survey summary......................... Stream survey summary 0a0 000 1 Management record............................ ~~~~ ~~~~ ~~~~ ~~~~ ~~~~ quality ~~~~ ~~~~ ~~~~ ~~~~ ~~~~ ~~~~ ~~~~ ~~~~ ~~~~ ~~~~ ~~~~ ~~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ ~~~ IV -1 1 1. 3 3 3 3 4 4 4 8 8 8 8 9 9 9 10 10 V-i V. REPORTS A. Style 1. Technica 2. Survey r( 3. Notes Il report series sport 0 0 0 0 0 0 0 0 0 0 0 ft 0~ ~ ~ ~ ~ B. Content of survey reports,.00 1. Abstract.............. 2. Introduction a. Name of water........ b. History of fishing. c. Objective of the survey 0 0 1 1 1 1. 1 1 1 1 V Page 3. 4. 5. 6. Methods and effort Results a. Limnology, water quality b. Composition of the fish community c. Biology of individual species Dicussion Recommendations and management alternatives 1 1 1 1 2 2 2 VI. APPENDICES A. Methods memos 1. Sample size for biological studies 2. Population estimates by mark-and-recapture 3. Estimating fish populations in lakes, from net catches extending over many days 4. Methods in age and growth analyses of fish 5. Mapping lakes with echo sounders 6. Instructions for winter lake mapping 7. Three methods for computing the volume of a lake 8. The coefficient of condition of fish 9. Creel census methods, in general 10. Calculation of weighted average length and weighted age composition 11. Endangered and threatened fishes in Michigan 12. Length-weight relationships 13. Sampling zooplankton in lakes 14. Measurement of stream velocity and discharge 15. Michigan stream classification 16. Instructions for sampling lakes and completing forms for the Inland Lakes Management Unit 17. Guidelines for sampling warmwater rivers with rotenone B. TABLES 1. Temperatures: Centigrade to Fahrenheit and Fahrenheit to Centigrade 2. Meters to feet and feet to meters 3. Inches to millimeters 4. Ounces to grams 5. Oxygen saturation at different temperatures VI Ct -s 0 0 -C 0 ct -a. 0 A t- 1 I. INTRODUCTION A. Perspective Surveys are important. They (1) document the characteristics of the state Is aquatic resources; (2). provide the factual basis for fisheries planning and management; and (3) supply data for other aquatic scientists and managers. Good surveys information becomes increasingly valuable as time passes and conditions change. Data collected by fisheries personnel over many years are essential for defining and understanding historical trends in fisheries and water quality. However, survey data become almost useless if their precision is in doubt, or if they are not recorded accurately or in sufficient detail. Quality control must be maintained for both present and future needs. B. Survey planning The problems of modern fisheries management are complex and diverse, and so are the types of information and surveys needed to solve them., Consequently., it is essential that survey objectives be carefully defined before field work begins so that the right data can be collected efficiently. In formulating survey objectives, consider the types of information needed, how precise it must be,, limitations of sampling gear, and financial and time constraints. The SURVEY PLANNING form has been developed to aid the planning process. C. Objectives and description ofPsurvey-modules -2 individual modules is the description of one facet of either the water body, the watershed, or the biota. Descriptive techniques will obviously vary between lotic and lentic environments, and with size of the water mass. The biota will be characterized as either fish or supporting organisms, with considerably more effort devoted to delineation of the fish population. It is recognized that seldom will there be occasion to complete a comprehensive study of a body of water, including its watershed and biota, in any one survey. However, it is advantageous to accumulate data in an orderly fashion by the completion of entire survey modules at every opportunity. In time, the summation of modules will thus furnish a complete description of all major waters of the state. The following survey modules will serve as a guide for the orderly accumulation of data. 1. Drainage and basin description The objective of this study module is to develop a description of the complete watershed of the subject lake or stream. The description should include the immediate drainage area and the lake or stream basin. Observations in the drainage should delineate characteristics which potentially may affect the subject body of water. Lake basin descriptions should include shoreline features, bottom types and critical habitat subject to potential human degradation. Critical areas might involve marshes, spawning areas or shoreline areas subject to dredging, filling or erosion. Stream descriptions will include observations of bottom types, stream profiles, volumes of flow, depths and critical areas subject to abuse and damage. 2. Limnology The objective of this module is to measure physical and chemical parameters which reflect the biological productivity of the body of water and delineate fish habitat. Properties to be measured include pH, alkalinity, nutrient concentrations, clarity, and temperature-oxygen depth profiles. -3 3. Plants and invertebrates The objective of this study module is to describe the biota, other than fish, insofar as they serve as indicators of productivity. The organisms of interest include phytoplankton, macrophytes, zooplankton, and benthos. Seldom do we have the luxury of sufficient time to enumerate abundance of individual species or even to make reliable estimates of community biomass. However, qualitative estimates of abundance often serve as indicators of productivity. Since phytoplankton is usually the most significant constituent of the primary producers, a measure of chlorophyll serves as the most practical measure of primary production. Estimates of both density and range of macrophytes are important not only as indicators of productivity, but also because of their role in fish shelter, spawning substrates, shoreline erosion protection, nutrient absorption, and indicators of general lake quality. Analyses of zooplankton and benthos are highly desirable whenever they are sampled with a specific goal in mind, such as trout lakes (see VI-A13). 4. Fish surveys Fish populations are usually studied for one of two reasons: (a) to describe as completely as possible an unstudied population, or (b) to evaluate apparent problems or past management programs. Descriptions of fish communities should be as precise and as complete as possible to facilitate comparisons with past and future data. It is imperative that sampling effort be accurately described and standardized. Data from various fishing gear should be analyzed separately since each has its own built-in bias. A basic description of the fish community will include (but not be limited to) species present, relative abundance, size frequencies, and if needed, growth rates. More detailed analyses of fish populations should contain a measure of rates of recruitment, growth, production, and mortality. Additional data might include standing crop population measurements or observations on endangered and threatened species (VI-A 11). -4 5. Fishery assessment Local reports of fishing quality are worth recording if they are screened rather carefully. These might include reported catch or complaints in addition to estimates of fishing pressure, harvest, value of the fishery, or evaluation of management techniques. An accurate analysis of a fishery, however, requires a well planned and managed creel census. Methods of creel census can be found in VI-A9 and assistance is available at the Institute for Fisheries Research. D. Forms and information systems Many of the survey forms have been revised or replaced, and additional changes may yet occur. The main objectives were to require greater precision (e.g., more size intervals in the length-frequency records), simplify the recording of field data and its transfer to final forms, provide reminders and space for the taking of field notes, encourage and aid the analysis of survey results, and get the data into formats adaptable to computerization in the future. Paper files for summary-type forms will continue to be maintained at four locations (Lansing, region, district, Institute for Fisheries Research) even after computerization is completed. Certain types of computations--length-weight regressions, mark-andrecapture estimates, back-calculated growth--can now be submitted on designated forms for machine processing. All forms are described in Section IV. 'I II- 1 II. SURVEY MODULES A. Drainage and basin descriptions 1. Lakes The LAKE PHYSICAL DESCRIPTION form is to be used to record observations of the watershed and the lake basin. Comments on the drainage should note potential problem areas requiring frequent observation. These would include areas of potential erosion, contamination or alteration. Sources of contamination should be brought to the attention of Department of Natural Resources enforcement personnel. Several lake basin measurements (area, depth) can be taken from topographic maps, while others (flushing rate) must be calculated in the office and may not be determined until needed. Heating degree days is required mostly for research purposes, and will be recorded by research personnel from the literature cited. All other information requested on the LAKE PHYSICAL DESCRIPTION form should be completed. Photographs of potential problem areas are valuable historical evidence, and can be filed with the report. 2. Streams The STREAM SURVEY SUMMARY form will be used to record characteristics of streams and their watersheds. Even though the form is designed to describe a stream, most of the recorded information will by necessity reflect study stations. A complete stream description will thus consist of the summation of data from several, or many, stations. Conditions on streams or their watersheds which are creating (or may create) management problems should be recorded. These include such things as: (1) erosion from stream banks, roads, timber cutting operations, development, etc.; (2) impoundments made by man or beaver, outflows from ponds dredged adjacent to streams, (3) barriers such as dams, culverts, waterfalls, etc.; and (4) pollution which might -2 involve chemical toxicants in the stream and/or aquifer, commercial fertilizers, sewer effluents (and seepage), sedimentation, temperature degradation, etc. The quality of streams as fish habitat is largely determined by the relative size, depth and frequency of pools. In general, good pools are deeper and wider than the average width and depth of the stream. Current must be reduced and cover should be present in order to constitute good fish habitat. Pools should be judged by their size, type and frequency. The following classification is from Lagler's (1952) "Freshwater Fishery Biology" (W. C. Brown Co., Dubuque): Size 1. Large: Pools having an average width greater than the average width of the stream. 2. Average: Pools having a width equal to the average width of the stream. 3. Small: Pools narrower than the average stream width. Type 1. Deep: Pools exceeding 2 feet deep; exposed pools with luxuriant aquatic plants harboring a rich fauna; or deep pools with abundant cover of logs, roots, boulders or overhanging bank, much drift or detritus, and shaded by bank vegetation. 2. Moderate: Pools intermediate in depth, shelter and plant abundance. 3. Shallow: Shallow exposed pools without cover and without plants; scouring basins. Frequency 1. Many: More or less continuous pools; ratio of pools to riffles about 75% to 25%. 2. Frequent: Rather close succession of pools and riffles in approximately a 50% to 50% ratio. -3 3. Infrequent: Long stretches of shallow riffles between pools; pools making up less than 25% of the entire stream area. All streams have been classified by the Michigan Stream Classification System (VI-A15), and the classification should be listed on the STREAM SURVEY SUMMARY form. Streams are classified by the following system: Top Quality Trout Mainstream.--Contain good self-sustaining trout or salmon populations and are readily fishable, typically over 15 feet wide. Top Quality Trout Feeder Stream. --Contain good self-sustaining trout or salmon populations, but difficult to fish due to small size, typically less than 15 feet wide. Second Quality Trout Mainstream. --Contain significant trout or salmon populations, but these populations are appreciably limited by such factors as inadequate natural reproduction, competition, siltation, or pollution. Readily fishable, typically over 15 feet wide. Second Quality Trout Feeder Stream. --Contain significant trout or salmon populations, but these populations are appreciably limited by such factors as inadequate natural reproduction, competition, siltation, or pollution. Difficult to fish because of small size, typically less than 15 feet wide. Top Quality Warmwater Mainstream. --Contain good self-sustaining populations of warmwater game fish and are readily fishable, typically over 15 feet wide. Top Quality Warmwater Feeder Stream. --Contain good selfsustaining populations of warmwater game fish, but are difficult to fish because of small size, typically less than 15 feet wide. Second Quality Warmwater Mainstream. --Contain significant populations of warmwater fish, but game fish populations are appreciably limited by such factors as pollution, competition, or inadequate natural reproduction. Readily fishable, typically over 15 feet wide. -4 Second Quality Warmwater Feeder Stream. --Contain significant populations of warmwater fish, but game fish populations are appreciably limited by such factors as pollution, competition, or inadequate natural reproduction. Difficult to fish because of small size, typically less than 15 feet wide. Streams, or stream sections, which currently receive significant runs of anadromous trout or salmon are also to be designated as trout streams, regardless of whether they are "trout" or "warmwater" according to the above classification. For a broader overview of the drainage characteristics, a narrative should be written describing the soils, topography, vegetation classification, land use, unique features, and problems. When more detail is desired and,. to provide a better conceptual picture of the drainage, a topographic map may be prepared showing its principal features. Streams are described by establishing habitat inventory sites which may be divided into zones and stations. a. Zones. --First, partition the stream into segments (zones) about 8 km long. This can be done on drainage topographic maps. If you want to number these zones, start at the stream mouth and number consecutively as you proceed up the mainstream to its source. Then number the tributary zones similarly beginning with the lowest tributary in the drainage (Fig. I1-1). b. Stations.--The station is the basic sampling unit where most measurements of the stream's physical, chemical, and biological parameters will be made. Select one (or more if necessary) sampling station near the center of each zone. The station must be representative of its zone and should be easily located from landmarks. c. Length. --A sketch of the sampling station should be made on the Field Map Sheet which is available for field use (Fig. 11-2). The sketch should indicate directional orientation and note prominent features of the landscape (roads, bridges, etc. ). The length of the station is measured down the center of the stream, and stream width is measured at 25-meter intervals. Determinations of average stream width and station area can -5 Tributary 1 Tributary 2 / ^ Main Stream Zones, ' Stations Figure II-1.--A graphic view of the sampling zones and stations within the stream drainage. M6.........................................................................r~..............R..................-...U...-........U -f Figur~eI1-*2.1 --Example of use *of Field Map Sheet to indicate length, width,. area and orientation of stream study station. -7 be made on the Field Map sheet. The length of the station can vary depending on density of the fish to be censused and your efficiency in capturing them. A 400-meter station is usually adequate for trout in northern lower peninsula streams. However, it appears that a length of 800 m may be required for trout in upper peninsula streams, because these streams generally have lower trout densities and lower electrofishing efficiency (due to lower conductivity). As a rule of thumb, for determining the length of a sampling station, electrofish until at least five fish in each size class common to the population have been captured. Electrofishing for trout is used here as an example but the rule applies for other target species and sampling gear. It is best to have the station terminate at a 50-m interval to minimize problems of calculation. Record these length intervals as in Table II-1. Both the upper and lower boundaries of the station should be permanently marked. Best markers are metal stakes placed at boundaries or pins driven into witness trees near boundaries. Describe the location of markers in field notes. d. Width. --Take width measurements at each 25-m interval as you progress downstream. Width is measured from water's edge (left bank) to water's edge (right bank) at a right angle to the bank. Record width as in Table II-1. Area can be calculated by multiplying average width times the station length. When an island occurs in the stream, width measurements should be taken across the stream including the width of the island (Fig. 11-3). Then subtract the area of islands to arrive at the water area only. A fairly accurate estimate of most islands in streams can be made with the following formula: island length X maximum width of island X 0.6. If the island is not of typical form (teardrop), then an array of width measurements should be taken. Area of the island is then calculated by multiplying the average width times length. Note that in the future we may wish to quantify certain measures of a fish population and express them in terms of the static water volume of a stream, its volume of flow per unit time, or even its total annual flow. These expressions may have a better biological basis for streams than the ones used at present--fish per unit length or fish per unit area. -8 Table I1-i. --Example of field record of measurements of station length, width and water depth. R1016-1 --.--,. RIVE C ALEYA OER C.AerQ EEK DATE: r OCr: I 1979~C STOrno FO bb.STR.H __LOCcATI N: r ý &, R. r 3 _ ____L rHH(m). TO 3 /00.12 / JV. /?S' eO. OoW 4760 s a? 3003;5=4 7as S 3 4 14S01 oicrif e(ar) 1.0 _$$4 0 Ws d'S0lJ Sf0? aO Vs $'? L, ls o 5"1 3 _ b(prtf a ~ W a'n in %rMa&) __ _3it hf /7 7 17Y 1.7 i- 7 DIo /133 1 it) of 60 / 7 /Dt ag3jo I /5 '4? 1.33 _! 0 L i.:3E 3 0 8 *0 30 /j.' 3gja --?S-a 1 1 3?7 Ij o 30 /.Ids38'30 io106-3 W- 1 %'Y-/1 71?703'Vi o00 oar Js.' 10S1(?10 i9 %5?33 %3 47 /0 I57 Sf.3416 3 St Y? 3Ia& _ _. % St $8 41 -?(4-_0 /7,.143 If3 '137 s&0 s1 rtT&S?3.3 6S"' ___ 3 41 Y12 f110.23416 1 V131 0/3' V/. / IS' 40 i 3 'TO D l _73 a vil Z I'vS -o V1 42.3. IV/ 13 vp Ar so Jbl 441 il -irs Y f __al Yit J 10 3 J? _o 3 3.01 3 ___s u u~i4 ~ 3IY~jg)~ IO O'.2..7332.25 I.a'.2I'(3ID13 1/ __ ~~1oU.,o lgi,3 Ui Jo~ YD/9,S /Alg~ /0 13? __ ___ jl I 'V~3 _ t /11 5 30 __d j6~bIL ----- vS t1 #O 4 / 1 07 J3 071 a-a s * __0 1 -_/5 13019 ___ 4 as.7o I5 pr /I m___ O 0 rr:ecor0 d Zerobs;or i- i 'eh 4 ife"rvas 0erj; _ _ - 0; +_ ns.eefs ehenr 1.hee ne +hra - _. 2-- ToTAtL Otq YJ sas~S8 -~ I. ________ ____ RVAA L 6 r; 3.' m avid C)OS SsC.7a7N.f1 1:/9.0if4"3in & _ARGCA ( 2pf S ý i ) _ Vo3, t 3 ----I C -it:d an a) b.0 0 r 4 $4O b.0 -a0 (0 "S4 4-3. -10 e. Depth. --Measure depth at 0.5-m intervals (0. 25 m, 0. 75 m, 1. 25 m., etc.) along the stream width cross sections. Record depth measurements as on Table II-1. Measure from the water surface to the top of the substrate. Be careful not to disturb the top of soft bottom sediments. f. Cross section profiles. --Cross section profiles graphically indicate the quality of stream fish habitat, since a summation of stream profiles indicates morphological diversity of the stream channel. Good stream habitat consists of a diverse blend of pools and riffles. Profiles can be drawn and their area calculated from each set of width and depth measurements. To calculate area, multiply the width times the average depth at each particular cross section. These profiles can be used to calculate the static water volume of the study station. g. Static water volume. --This parameter has considerable biological significance because it is the total potential living space available for fish. To calculate the static water volume within the sample section, first determine the average cross sectional profile area. The average profile area times the section length equals static water volume. This approach eliminates problems caused when islands occur within the sample station. Do not calculate the static water volume by multiplying the average depth of the cross sections times the average width times the sample section length. This procedure gives an overestimate of water volume. h. Discharge. --The best place to measure stream discharge in the sampling station is where the stream channel is straight and canal-like. The more laminar the water flow, the better the velocity measurements will be. Discharge measurements should be made using standard procedures with a Gurley current meter (VI-14). Note, since the meters available at present are calibrated in English units, discharge will have to be calculated in these units, then transformed to metric units (m3/sec). The best time of the year to measure discharge for our purpose is during October or November because the streams are generally in their most stable flow conditions -11 and near their average seasonal flow. Take measurements 3 or 4 days after the last precipitation. i. Velocit.--Average stream velocity can be calculated by dividing discharge by average cross sectional area., Velocity is highly variable within a cross section., between cross sections within the stream reach., and at different stream stages or discharges. j., Annual stream discharge. - -In the future we may want quantitative measurements of populations in terms of numbers, biomass, or production per total annual volume of flow. To obtain the annual discharge for a stream, it is best to have a continuous recording of the water height (stream stage). This., along with discharge measurements at an array of stream stages., provides the means to construct a rating curve from which the annual discharge can be calculated., A second method is to calculate annual discharge from -known monthly flow periodicity. A third method, that is less precise but satisfactory for our purpose., is to assume that discharge (in m3 /sec or c. f. s. ) during October or November equals the average discharge during the year and multiply it by 31, 557,t 600 (the number of seconds in a year). k. Streamstae --Stream stage is the relative change in water surface height as measured on a staff gauge. It is best to record this continuously with an automatic recorder. Next best is to read it daily or periodically. As mentioned earlier., if the stream stage is known, and there is a stream discharge -rating curve for various stream stages., the total river flow can be determined. 1. Gradient. - -Stream gradient., expressed as -drop in elevation per kilometer or percent slope., can be estimated from contour lines, of U. S, G. S. to-pographic maps. More precise measurements would require -12 Another way of measuring bed type or composition is to take scoop samples along the line transects with appropriate sampling apparatus, then sieving the samples through standard Tyler sieves to determine the size distribution of the particles. n. Spawning areas. --In the past many surveys have attempted to assess spawning areas for salmonids based upon the percent gravel in the streambed. There are reservations as to the value of this approach because not all gravels are used by fish. Use depends upon factors such as groundwater upwelling, temperature, dissolved oxygen, bed porosity, bed permeability, and the salmonid species and their size. A more accurate assessment of spawning habitat can be made by walking or canoeing the stream during the spawning period and noting where redd building activity and spawning actually occurs. o. Cover. --Cover can be in the form of logs, brush, rocks, turbulent water, turbid water, water depth, undercut banks, or objects hanging over the water--anything providing shelter for fish. Cover is highly variable, and its characteristics are not readily quantified. Subjective terms such as "good", "moderate", or "poor" are usually adequate for stream inventories. B. Limnology 1. Lakes Routine limnological measurements will be made and recorded on the LIMNOLOGY form. Two levels of intensity will be employed in limnological lake surveys, depending on the scope of other biological studies being conducted. A first level survey will be associated with routine fish collections or other sampling, short of a complete biological survey. A survey at this level will mostly be restricted to the measurement of parameters that will assist in fish sampling. a. First level survey. --Measurements to be made in a first level survey include dissolved oxygen and temperature, depth profiles, alkalinity, Secchi disk, observations of water color, and influential weather -13 conditions. Alkalinity measurements might be omitted if reliable data have been collected within the past 5 years indicating that the lake has a total alkalinity in excess of 80 ppm. Soft water lakes should be monitored at every convenient opportunity due to their lack of buffering capacity and consequent susceptibility to degradation by such phenomena as acid precipitation. Temperature and oxygen depth profiles should be determined prior to fish sampling with any type of nets if the lake is stratified. Knowledge of these factors can prevent much wasted effort from fishing depth strata unsuitable for the target species of fish. A depth sounder should be used while setting nets, and the depth at each end of the net is to be recorded. The temperature range and the dissolved oxygen concentration within the strata fished can then be determined from temperature and oxygen depth profiles. Complete temperature and oxygen depth profiles are not always necessary when netting during spring and fall circulation periods. However, sufficient temperature measurements must be made to assure that the lake is in a state of complete circulation. If circulation is not complete, anoxia may persist in the bottom strata. Water transparency and color are valuable observations since they reflect the magnitude of plankton production. The Secchi disk is possibly our best available indicator of the basic productivity of a lake. b. Second level survey. --A second level limnological study is to accompany a complete survey of a lake. In addition to the first level measurements, a second level study will include on-site observations of abundance of aquatic vegetation and the detection of pollution, or other water quality problems, which may need more study by the Water Quality Division. Water samples will also be collected and sent to the Environmental Services Laboratory for extensive chemical analysis. The results from these analyses will be incorporated in the data storage bank of the Inland Lake Management Unit of the Land Resource Programs Division as part of their intensive lake surveys. These data will be stored in STORET, but will also be available for our files. Sample and field information requirements are contained in VI-16. S14 The Environmental Services Laboratory will analyze the following parameters for all lake surveys: pH Total phosphorus Total alkalinity Soluble ortho -phosphorus Conductivity Nitrate and Nitrite Chlorides Ammonia Suspended solids Organic nitrogen Total solids The following parameters may be measured also the first time a lake is surveyed. These will include: Hardness Total iron Turbidity Magnesium Silica Potassium Calcium Sodium Sulfate Total organic carbon It is essential that both on-site measurements and collection of water for laboratory analysis take place during the time of maximum summer stratification- -mid-July to mid-September. This is the only time that we can determine the maximum extent of oxygen depletion in the hypolimnion, and consequently., the suitability of the lake for cold water fish. I~t is essential that a schedule of lakes to be included in the intensive surveys be sent to the Inland Lakes Manage.ment Unit during the December prior to the surveys. This. enables the laboratory to schedule the analyses required. Laboratory services are allotted in January for the entire year. 2. Streams -15 drainage, including major tributaries. They should be read weekly for one full year, or for at least one summer. One year of data will usually provide a good picture of the temperature regimes within the stream drainage. Salmonids have highest populations in streams with the least amount of variation in seasonal and daily temperatures. Also these are the streams with the lowest average annual water temperature, particularly low average summer water temperatures. Undoubtedly, warmwater fish species also benefit greatly from relatively stable water temperature regimes, but, of course, on the warmwater side of the temperature scale. b. Water chemistry. --Water analysis for dissolved oxygen, alkalinity, and pH are recommended for streams, for they are key indicators of the general quality of the environment. More intensive and varied chemical analysis should be done if pollution or some abnormal condition is suspected. For example, large daily fluctuations in the D. O. point up pollution problems. Many other chemical determinations, such as hardness, total solids, phosphorus, nitrogen, etc., might be of interest, but are too expensive for general surveys. 3. Limnological methods a. Temperature. --In lakes, water temperature measurements should be made in ~C with an electronic thermometer. A temperature reading should be taken, and recorded, at every meter of depth with the exception of the following conditions: 1. If, within the epilimnion or hypolimnion, there is no change from the reading of the previous depth. 2. If, during the spring or fall overturns, temperature is uniform with depth. The electronic thermometer should be standardized with a good laboratory thermometer at least once per year. In streams, or at lake surfaces, temperatures can be taken with a pocket thermometer. However, a pocket thermometer should not be used to record the temperature of a water sample that has been collected with a Kemmerer sampler and emptied into a glass bottle. Water is appreciably -16 warmed as it is lifted through the epilimnion and emptied into a bottle. Temperatures taken in this manner can be in error by as much as 5 degrees. When taking air temperature, be sure the thermometer is dry and shaded from the direct rays of the sun. b. Dissolved oxygen. --Oxygen determinations must be made at sufficient depth intervals to accurately delineate stratification within the lake. Temperature stratification should be determined prior to conducting oxygen analysis. Samples for oxygen analysis should then be collected at the surface, top, middle, and bottom of the thermocline, middle of the hypolimnion, and within 1 m of the bottom. These samples should be analyzed on the lake, and then additional samples taken to describe oxygen depletion. You should look also for an oxygen maximum in the thermocline, since this is an indication of high phytoplankton abundance. If oxygen samples cannot be titrated on the lake, then additional samples must be taken initially. Samples should then be collected at the surface and bottom of the epilimnion, and every 2 m of depth from the top of the thermocline to the bottom of the lake. The oxygen content of water can be measured either by an oxygen probe and meter or by chemical analysis. An oxygen meter is advantageous when a large series of samples is to be run frequently. However, infrequent analysis of a few samples can be done almost as conveniently by chemical methods. An oxygen meter must be standardized in a water sample previously analyzed by a chemical method. Standardization must be repeated daily. Thus a few samples can be run chemically almost as fast as a meter can be standardized. The Winkler method of chemical analysis will be used. Several modifications of this method have been advocated for waters containing various interfering substances. However, these substances are sufficiently rare in unpolluted natural water that we will use the unmodified method. * Water is collected from a desired depth with a Kemmerer water sampler, and ttansferred to a 250-ml BOD bottle by inserting the tube of the sampler to the bottom of the bottle. Care must be taken to flush the bottle about -17 two times its volume and not to retain air bubbles when inserting the ground glass stoppers. 1. Fixing: Three reagents are added to the sample with automatic pipets, as follows: a. 2 ml manganous sulfate (MnSO4); deliver below the surface of the water so as not to introduce air bubbles. b. 2 ml alkaline-iodide solution (potassium or sodium; KI-KOH or Na-KOH); add immediately following the MnSO4. Deliver below the surface as before. c. Replace stopper and mix thoroughly by inverting bottle repeatedly. Allow precipitate to settle until top half of bottle is clear. d. 2 ml concentrated sulfuric acid (H2S04); deliver carefully below the surface of the sample. Restopper and shake until precipitate dissolves. If precipitate does not dissolve immediately, allow to stand for several minutes. 2. Titrating: The sample is now ready to titrate with 0.025 N sodium thiosulfate (Na2S203) for final analysis. Titration may be done immediately in the field, or samples may be returned to the lab and held for several days. If necessary to delay titration, store samples in the dark. The titration procedure is as follows: a. Transfer 200 ml of sample to a 250-ml Erlenmeyer flask. b. Titrate with Na2S203 until pale yellow color. c. Add a "1pinch" of Thyodene (starch substitute) for pale blue color. d. Continue titration until colorless. The number of ml of Na2S203 used in the total titration is numerically equal to the dissolved oxygen concentration in parts per million (ppm or mg/liter). -18 3, Reagents: The reagents used in the Winkler method of oxygen analysis are prepared as follows: Manganous sulfate solution: Dissolve 480 g MnSO4 4H20 or 400 g MnSO4. 2H20 or 364 g MnSO4. H20 in distilled water, filter and dilute to 1 liter. Alkaline-iodide reagent: Dissolve 500 g sodium hydroxide (NaOH) or 700 g potassium hydroxide (KOH), and 135 g sodium iodide (Nal), or 150 g potassium iodide (KI), in distilled water and dilute to 1 liter. Sulfuric acid: Purchase concentrated solution. Sodium thiosulfate: Purchase Acculute brand (Anachemia Chemicals Ltd., P.O. Box 87, Champlain, New York 12919) of standard volumetric solution. This comes in a small bottle which is emptied into a 1-liter volumetric flask. The bottle is filled with distilled water and emptied into the flask three times, to assure complete rinsing, and the flask is then filled with distilled water. The liter of solution will be exactly 0.025N, and will not need to be standardized as required in the past. The solution will keep for at least 6 months if refrigerated. Thyodene: Purchase (Fisher Scientific Co.) and use as supplied. c. Alkalinity: Samples should be collected from the surface, middle of the thermocline, and within 1 m of the bottom. Phenolphthalein and methyl orange, or total alkalinity, are to be determined by the chemical method, as follows: 1. Water is collected with a Kemmerer sampler, and 100 ml is transferred to an Erlenmeyer flask. -19 2. Add 4m5 drops of ph-th indicator. If the sample remains clear, record 0.0 ph-th alkalinity. If the sample becomes pink, titrate with 0.02N sulfuric acid until clear. Ten times the number of ml of acid used equals the ph-th alkalinity. 3. To the same sample add 3-5 drops M.O. indicator, and, without refilling buret, continue titration until yellow color changes to salmon pink. Record total alkalinity (M. 0. alkalinity) as 10 times the total number of ml H2SO4 used in both titrations. 4. Reagents: The reagents used in the alkalinity determination are prepared as follows: Phenolphthalein (ph-th) indicator: Dissolve 5 g phenolphthalein in 500 ml of isopropyl alcohol and add 500 ml distilled water. If necessary, add 0.02N sodium hydroxide (NaOH) dropwise until faint pink color appears. Methyl orange indicator solution: Dissolve 500 mg methyl orange powder in distilled water and dilute to 1 liter. Sulfuric acid, 0.02N: Purchase Acculute solution and dilute to 1 liter. See instructions for sodium thiosulfate in dissolved oxygen methods. d. Secchi disk depth. --The transparency of water is measured by determining the depth at which a Secchi disk disappears from view when lowered through the water column. A Secchi disk is a metal plate 20 cm in diameter, with the face divided into four quadrants. Two opposite quadrants are painted black and the other two are white. A graduated line is fastened to an eye bolt in the center of the disc. Standard conditions for the use of a Secchi disk are as follows: bright day, sun directly overhead; shaded, protected side of the boat; without polarizing sunglasses. The Secchi disk is lowered into the water, noting the depth at which it disappears, -20 than lifted, noting the depth at which it reappears. The average of the two readings is recorded as the Secchi disk depth or limit of visibility. The depth should be recorded to the nearest 0. 1 m. e. Color. --Michigan waters are either colorless (lakes may appear to be blue or green) or stained brown by humic acid from organic drainage. Color will be recorded as either clear, light brown, brown, dark brown, or turbid. Color may be determined by examination of a sample in a bottle, or as observed against the Secchi disk held a few centimeters beneath the surface. f. Environmental Services Laboratory analysis. --Water samples for laboratory analysis must be received at the lab within 48 hours, and must be kept cold until delivered. From most areas of the state, this can be accomplished by either DNR aircraft or commercial bus. Fisheries Division personnel will pick up samples at the Lansing airport or bus depot if arranged by telephone. The Inland Lake Management Unit will furnish station location sheets and three laboratory analysis sheets. These forms should accompany the samples to the laboratory. Detailed instructions for handling samples and forms are contained in appendix VI-A-16. Samples for nutrient analysis should be collected at the surface, mid-depth (thermocline area if one exists), and within 1 meter of the bottom. Three 500-ml plastic bottles of water from each depth are required. One bottle from each depth is to be preserved as directed. g. pH. --Despite the fact that biologists have been recording the pH of water for many years, there still seems to be no satisfactory method of field measurement. Portable pH meters are the preferred method if one is available that proves to be reliable. If a meter is not available, a HACH kit should be used. Most municipal sewage treatment plants wil do pH analysis upon request. -21 C. Plants and invertebrates 1. Lakes a. Macrophytes. --Abundance of littoral vegetation is to be recorded on the LIMNOLOGY form. Abundance estimates are to be made for various forms of aquatic plants including submergent, emergent, floating, and Chara. Aquatic plants are good indicators of lake eutrophy. Traditionally biologists have made a single statement evaluation of macrophyte abundance throughout an entire water body. Plant abundance has the potential of giving us more information than we have utilized if we can be more precise in recording our observations. This may prove to be one of our most significant historical observations for evaluating cultural eutrophication. The recorded observations for each form of vegetation should consist of one or more percentage figures representing the percent of the littoral area where that growth form is common (C), abundant (A), excessive (E), etc. For example, if emergent vegetation is sparse in 60% of the littoral, common in 20% and excessive in 10% the recorded notation should read: Emergent 60 S, 30 C, 10 E. The recorded percentages should always total 100% of the littoral. b. Chlorophyll. --Chlorophyll analysis is the easiest and most practical method of recording phytoplankton abundance. This is also a useful historical measure of eutrophication. Chlorophyll analysis will be conducted by the Inland Lake Management Unit. These samples must be scheduled in advance of collection. Chlorophyll requires special collection and handling techniques. A special composite sampler (Fig. 11-4) is used to collect a composite sample throughout the water column from the surface to a depth of twice the Secchi disk transparency. The sample is placed in a 250-ml dark bottle, and one drop of magnesium carbonate is added as a preservative. c. Fish food. --The sampling of zooplankton and benthos is a time consuming task and is not recommended for routine lake surveys. -22 ng ng Amber Sample Bottle (32oz.) Fruit Juice. Can (48 oz.) Retaining Wire (Clothes Hanger),ýEye Bolt KNutS (One Inside Can + One Outside) i I I i I I I 1 I I I i I I I I I I Figure 11-4. --Phytoplankton (chlorophyll) sampler construction plans. -23 However, sampling for large zooplankters, as described in Appendix VI-AI3, is recommended for special surveys of lakes in which (1) stocked trout are not providing satisfactory returns and (2) survival of walleye or other young game fish is poor. For routine surveys, simply make observations on fish food organisms while conducting other parts of the survey. Watch for zooplankton blooms, insect hatches, burrowing mayflies (or their burrows), crayfish, and forage fish. Report noteworthy observations on the LAKE SURVEY SUMMARY form or on a NOTES AND REFERENCE form. 2. Streams a. Vegetation.--To assess the standing crop (or production) of plants growing in streams is extremely difficult. For most surveys, the best we can afford to do is to subjectively estimate the percent of the channel in which vegetation is "abundantS', "moderate", or "sparse". The type, size class (height), and degree of shading provided by vegetation adjacent to the stream should be noted also. For example, canary grass that overhangs a stream bank or dense tag alders (up to 12 feet high) that form a dense canopy over the stream. b. Fish food. --An estimate of the relative abundance of fish food can be made from two square-foot samples of bottom fauna--one from the middle of the stream and one midway between the center and a stream bank. Take the samples with a Surber Sampler, or a similar device, and calculate the average number and volume of organisms. The resulting estimates, based on only two samples, will be quite rough, but much more extensive sampling is required for good quantitative estimates of abundance of benthos. Use the mean numbers and volume (or weight) of fauna from the two square-foot samples to classify the stream for food richness as follows: Exceptional richness: Volume greater than 2 ml, or 2 g, and number of organisms greater than 50. Average richness: Volume from 1 to 2 ml, or 1 to 2 g, more than 50 organisms. -24 Poor richness: Volume of benthos less than 1 ml, or 1 g, and (or) fewer than 50 organisms. In order to qualify in any richness category both the numerical and weight or volume requirements must be met by the mean square-foot sample. D. Fish surveys 1. Discussion Samples of fish may be desired for studies at one, or all, of three levels: (a) community (species diversity and relative abundance of species), (b) population (abundance, distribution, length-frequency, age frequency, growth, etc. of a species population), or (c) individual (specimens). The sampling of communities and populations will be emphasized in the following discussion because it is essential to fisheries management and the most difficult part of fish surveys. It is difficult to obtain a completely unbiased sample of fish living in natural habitats. Catches are nearly always affected by at least three factors: (a) gear selectivity (influencing species caught, relative abundance, size distribution, and sometimes whether the more active or the more passive individuals are captured), (b) differences in gear efficiency among habitats (e.g., most types of gear sample the shallow littoral zone most effectively), and (c) daily and seasonal changes in the behavior of fish which alter their vulnerability to capture. In addition, care must be exercised to avoid further bias when the catch is subsampled for length-frequency, age and growth, survival rate, etc. Usually, our aim in field surveys is to obtain a representative sample of the species and sizes of interest. Unless our interests are very narrow (i. e., targeted), a variety of gear types, habitat types, sample sites, and sample dates will be required for a good representative sample. Within this context, fish sampling should provide: a. Enough fish of the right species and sizes to be statistically meaningful. -25 b. An orderly and reliable information and data base.. c. A means of systematically identifying change. d. The specific information needed to solve a specific problem. The objective(s) of the survey, the. target species., and the types of information needed must be defined in advance. Types of surveys include (a) a basic inventory of all species, (b) an inventory of principal (target) species, and (3) a check on a specific problem or management procedure. The purpose of the survey is to be recorded on the completed FISH COLLECTION form to aid others in the interpretation of survey methods and results., Careful planning, as well as execution, is essential for meeting the objective. A SURVEY PLANNING form can be used to plan surveys. The purpose of this form is to assist in review of past surveys., setting an objective for the proposed* survey, and communicating this information to others. Dispose of the form after the survey report is completed. Other forms aid in the recording and analysis of data. These allot some space to analysis and interpretation, but extensive surveys should culminate in narrative survey reports. as well., Central to the forms are four tables and one figure which summarize key statistics of the fishcommunity and its species populations. Usually, one or more of these summaries will be needed to answer your questions and diagnose management problems. a. CATCH SUMMARY, by gear type: Species Length Avg. Wt. U -26 Rev. 1/82 This table records the species taken, average length and weight, S the actual catch by number and weight, the percentage contribution of the species to the sampled portion of the fish community (total %o by number and by weight), an index of population abundance (CPE), and the proportion of the catch which exceeded the minimum legal size limit or was large enough to be acceptable to anglers (L-A). These key statistics generally reflect the status of the community and its species populations and are useful for detecting changes through time. At some future date, statewide averages or standards will be available for making comparisons. b. LENGTH-FREQUENCY and LENGTH-BIOMASS, by gear type: Species Inches No. Lb. 1 2 S3 This table, derived from a random sample of the catch, shows the size structure of the population and enables the calculation of average size and Jo L-A. A desirable size structure has both small and large fish, indicating that recruitment is taking place and survival and growth are adequate to produce large fish and a fishery. The optimum ratio of small to large sizes has yet to be defined for each type of gear. The CATCH SUMMARY, LENGTH-FREQUENCY, and LENGTHBIOMVASS tables are on the FISH COLLECTION form. Some space is provided on this form for analysis and interpretation. Other parameters are recorded and interpreted on the forms that follow. 0 -27 c. FISH GROWTH, by gear type (form 8070): Length Average State Avg. growth Age Number range length avg. Growth index index Species group of fish in inches in inches length by age group for species This table records the statistics of the growth sample and compares the average length of the sample to the state average. In the analysis section of the form it is appropriate to also indicate how the growth indices compare to previous samples. Growth rate is a most useful measure of a population's well being. Slow growth commonly indicates that recruitment is not properly balanced by mortality--within the constraints of the food supply. Conversely, fast growth suggests that recruitment and overall production could be improved. d. LENGTH-WEIGHT REGRESSION (form log W log L This figure, or its equivalent equation: logW = log c + n log L, is a measure of the well being (plumpness) of individuals in the population and is handy for converting length-frequency data to biomass-frequency data. Some state-average data are available now, and additional research is being conducted to develop useful standards. -28 e. POPULATION ESTIMATES (form ) Species Estimated:No. /acre Lb./acre % L-A: By No. By Lb. Inch No. Recapture run Estimates Estimates by age group group marked Recaps Unmarked No. 95% limits Lb. No. aged 0 I[I.. Total_______________ _________ __ 1% survival | More sophisticated management problems at the population and community levels require absolute, rather than relative, measures of population abundance and size frequency. Mark-and-recapture methods, stratified by size groups to eliminate bias caused by size selectivity of gear, are practical in some situations--especially in wadable streams. While the population is being estimated, it is usually wise to take a large number of scale samples so that the age composition of the population can be accurately determined. From these data, it is possible to make a good assessment of recruitment, survival, and biological production. However, the best method of determining survival is from age group estimates made in consecutive years. A low rate of survival commonly signals problems of over fishing or excessive natural mortality. 2. Procedures It is not possible to design a single (or a few) sampling plan suitable for all fish surveys. To a considerable extent, the design of each survey must be customed tailored to the survey objectives, species, habitats, degree of precision required, budget and time limitations, and previous experience. The following discussion of procedures is specific in routine matters (where feasible), but hopefully the more general sections will broaden the reader's understanding of sampling problems and enable him to design efficient sampling plans as the need arises. -29 a. Planning. --Review I-B and II-E1. The survey objectives, and the types of summaries and forms required must be established before field work begins. An important aid to every survey is a map or sketch of the lake or stream. Use it to select and record the location of sampling stations, net sets, transects, and electrofishing areas, and to note spawning areas, brush or rock shelters, land marks, and other information. The map should be stored for future reference, and as is practical and relevant, sketched on the FISH COLLECTION form or a NOTES AND REFERENCE form. b. Forms and records. --The quality of our records reflects our degree of professionalism. In the field, use FISH COLLECTION forms to tabulate the catch and the length-frequency data (or plain waterproof data paper) and as a guide for recording the appropriate information about habitat. The LENGTH-WEIGHT FIELD DATA form is handy for taking weight data. Generally, avoid getting too complicated when recording data in the field as this increases errors and slows down the crew. For continuous recording during stream electrofishing, the formats of tables II-4 and II-5 are recommended. Keep separate records of catch and effort for each gear type, collection site, and index site. In the office, as soon as possible afterwards, summarize the data, combine records for collection sites (if there is no reason to report them separately) and carefully prepare the appropriate summary forms for distribution and filing according to the instructions below and in Section IV. Store the field sheets also, if they contain potentially useful data not on the summary version. c. Fish identification. --All fish must be identified accurately. If there is any question on identity save a sample for later examination. The I. F. R. and the University of Michigan Museum staff can provide assistance. Species which are threatened, rare, or endangered, or outside of their normal range or habitat may be of special interest to the Museum (see VI-A 1). -30 d. Measuring fish. --Standard units of measurement are inches and pounds (decimal). Length. Measure total length of fish to 0. 1 inch if: (1) Fish are scale sampled for growth (2) Fish are weighed individually or in small groups (3)A more accurate (see below) estimate of average size is needed (e. g., small minnows or young sport fish) Otherwise, measure fish to inch group. Inch groups are defined as: 0 inch group = 0. 1-0. 9 inch, 1 inch group = 1.0-1.9 inches, etc. Weight. Carefully measure weights of individual fish (panfish to 0. 002 pound). Very small fish may be weighed in small groups to obtain an average weight for the inch group. Make measurements on a stable platform, out of the wind. Extremely large catches of fish may be estimated from bulk weights and subsample counts and weights. e. Selection ofsample sites. --Enough habitats and sites must be sampled (with appropriate types of gear) so that an experienced biologist feels confident that a representative sample has been obtained. In surveys seeking one or a few target species, it is permissible to concentrate effort in habitats and at sites that previous experience suggests are likely to yield a representative random sample (within constraints of the gear) with respect to length-frequency, age-frequency, growth, or other population characteristics of interest. However, bear in mind that fish behavior is not completely predictable. Basic inventories require a representative sample of the entire fish community and some effort must be expended in all habitats to obtain information on species diversity and fish distribution. Additional sampling effort may be expended in habitats containing (or most likely to contain) species of greatest importance. This procedure provides an experienced -31 surveyor with the greatest amount of useful information from the least amount of effort, but invalidates a strict comparison of CPE among species. Lakes. --Data required to complete the LIMNOLOGY form should be collected just prior to the fish survey if the lake is stratified. Use the temperature, DO, and depth information to aid in the defining of habitats and the selecting of sample sites. Other criteria useful for defining habitats are vegetation, substrate, current, cover, and morphometric features such as bays, points, inlets and outlets. Use an echo sounder to locate sample sites. Record sample site depth, temperature, and other habitat data on the FISH COLLECTION form. Streams. --Stream surveys should be conducted within the framework that the drainage is the ultimate management unit, thus the main survey unit (see II-B2). This can be accomplished by systematically subsampling various segments (reaches) of the stream drainage. Then by summing the values obtained from the subsamples, values for the drainage as a whole can be obtained. This approach is particularly important for the assessment of fish populations and angling. f. Index stations. --Index stations may be established to monitor seasonal or annual trends in the CPE index of abundance for a target species. An index station may be used for more than one target species, but at least 10 specimens of each species must be taken at each station, or among all stations combined, to provide useful statistics. In lakes, replicate sample each index station (e.g., at least two net nights per survey) and, for year-to-year comparisons, obtain CPE's at the same time of year with the same type of gear. Select index stations after an understanding of habitats, and fish abundance and distribution within the lake or stream have been attained from a basic inventory. Choose some sites because large and consistent catches can be made there, others because they represent important habitats and geographic areas. Enough stations must be established, or enough supplemental sampling must be done, so that shifts in fish distribution are not misinterpreted as changes in abundance. Minimum guidelines -32 are five index stations for lakes 10 to 100 hectares and ten stations for larger lakes. Record the location of index stations on maps and, if feasible, on fish collection records. Check previous surveys before assigning index station numbers to avoid duplication. Sites sampled during a survey may be assigned a temporary number, called a "Collection Site No., " rather than a permanent index number. The location of numbered collection sites is to be recorded on the FISH COLLECTION form. Data may be sumnarized by collection site or index site, as indicated on the forms. g. Selection of gear. --All types of fishing gear (including poisons) are selective by size of fish and by species. Furthermore, their efficiency varies according to habitat. To inventory a target species, the most effective gear should be selected. For comparison with an earlier survey, use the same gear as before. For a basic inventory of the fish community, the sampling gear should be adequate and diverse enough to sample all habitat types and all species in rough proportion to their abundance. Basic lake surveys require the use of gill nets, trap nets or fyke nets, plus seines or 220-volt AC electrofishing equipment. In shallow lakes (less than 30 feet deep), allot more effort to trap netting than to gill netting; in deep lakes, do more gill netting than trap netting. In wadable streams, the best gear for sampling fish is the 220-volt DC stream shocker. Non-wadable streams are difficult to sample. Boom shockers with 220-volt AC or 220-volt DC are usually the best types of gear. In sluggish current, fyke nets or seines may be useful. Rotenone may be used to sample river populations (e.g., Grand River in 1978). The fish are collected in a blocking seine at the lower end of the sample areas. The rotenone is detoxified with potassium permanganate as it leaves the sample areas. -33 h. Duration and effort..--A survey should continue long enough, and be intensive enough, to obtain a representative sample of all important species. Usually this means a minimum of 30 fish of each of the species. This goal may not be feasible if the fish prove to be difficult to catch (e. g.o mid-summer netting in lakes). Netting in lakes should extend over two or more nights. The following table may be used as a guide for planning the amount of netting (trap + fyke + gill) required for an adequate sample: Lake area (hectares) Net nights 1-10 6 10-100 6-20 100-1000 20-50 1000+ 1 per 25 ha i. Catch per effort (CPE). --Catoh per effort is a useful index to fish abundance, especially for monitoring changes in a species at index stations. Standardized gear and effort are prerequisite. For all fish surveys catch and effort are to be recorded for each gear type, and corresponding CPE 's are to be calculated on the FISH COLLECTION form unless the collector notes why the CPE statistic would not be representative. Possible reasons for a non-representative statistic include faulty gear, incomplete records of catch, or nets not being set overnight. Catch per effort is expressed as both number and weight caught per unit of effort. Catch per effort information should be part of final reports and should be used for comparisons with past surveys (Table 11-2). It should be understood that CPE is a highly variable statistic and that only major increases or decreases or clear trends through time should be interpreted as reflecting real changes in fish abundance. Selectivity of gear makes comparisons of CPE across species difficult. Rather, the relative abundance of species in the community should be expressed on a rank basis (rare, sparse, common, or abundant). -34 Table 11-2. --Number of fish caught per trap net and gill net lift at East Twin Lake during 1940, 1966, 1969, and 1975. Number of lifts given in parentheses. Trap nets Gill nets Species 1975 1969 1940 1975 1966 (38) (16) (560) (16) (18) Yellow perch 0.08 10.00 - 5.06 17.94 Walleye 0.45 2.88 4.85 1.06 1.72 Smallmouth bass 4.26 - 1.68 0.06 0.17 Largemouth bass 2.39 0.06 0.11 0.25 -Bluegill 0.18 0.06 - 0.26 0.11 Pumpkinseed 4.50 0.19 2.89 0.06 Rock bass 3.11 0.38 1.04 - 0.11 Tiger muskellunge 0.08 - Northern pike 0.03 - Channel catfish 0.03 Common white sucker 2.89 11.75 2. 28 1.63 0.67 Brown bullhead 0.08 0.19 0.08 tI-35 Rev. 2/82 Table 11-3. --Standard units of effort for CPE (Part A); and comparison of three types of CPE for trap, fyke, and gill netting (Part B). Part A Gear Standard units Trap or fyke net ) Inland experimental gill net) Great Lakes gill net ) Large seine Minnow seine Toxicant sampling Trawl Visual observations Catch per net lift (with overnight setsXA} Catch per acre seined Catch per haul Catch per acre of area sampled Catch per 5-minute unit of "actual fishing time" or catch per acre Adjust as appropriate Catch per hour Catch per set hook per lift Angling Set hooks Electrofishing Lakes and non-wadable streams Wadable streams Catch per hour of actual fishing time (15 minutes minimum effort) Catch per mile or catch per acre Part B Number of CPE units Number Number Net Net Nights of of of nights lifts nights netting nets between lifts (standard _ (optional) I(optional)& 1 1 1 2 2 2 0 1 2 or more 0 1 2 or more 0 1 1 0 2 2 0 1 0 0 2 0 0 1 2 or more 0 2 4 or more etc. V "Net lifts" are the standard divisor for trap, fyke, and gill netting CPE computations on the FISH COLLECTION form (R8058). A net lift is defined as a set over one or more nights (i. e., excludes sets not made overnight). u "Net nights" are an optional, more precise, unit of CPE. Record the number of net nights in the space provided on the front of the FISH COLLECTION form for possible use. A net night is defined as a 1-night set. 1~ "Nights of netting" is another optional measure of CPE for use in reports or analyses. Nights of netting is defined as the total number of nights a net was fished, irrespective of the number of lifts. -36 More precise measures of fish community structure require actual population estimates of each species, or CPE's adjusted for gear selectivity. Table II-3 presents units of effort required to calculate CPE for various types of gear. j. Length-weight relationship. --Individual lengths and weights of important species should be obtained during inventories so that lengthweight regressions can be computed. Use the regressions to determine relative plumpness, and (see II-Eh) to expand length-frequency data to length-biomass data and total biomass of the catch. Obtain the individual lengths and weights on a sample of about 10 fish per inch group per species. For small fish which are difficult to weigh individually, weigh all 10 fish together to obtain an average. Weigh panfish to 0. 002 pound (1 gram), if possible. Take the weights carefully, on stable footing, out of the wind. Record lengths and weights on scale envelopes, if scale samples are being taken, or on LENGTHWEIGHT FIELD DATA forms. Later, transfer data from the scale envelopes to SCALE SAMPLE ANALYSIS forms. Computer analysis of these forms is available, saving step 1 below: 1. Calculate: log W = log c + n log L or plot W and L on log-log graph paper: W "a ' 1975 0'e.. \ L L 2. Fill out the LENGTH-WEIGHT REGRESSION form. Evaluate relative plumpness by comparing the regression slopes (n), or the displacement of the lines on a graph, to prior samples. In the example graphed above, the fish are now heavier at the same length than they were in 1975. State standards (VI-A12) may also be used for comparison. Keep seasonal changes in mind (e.g., spawning) when making comparisons. -37 k. Length-frequency. --Samples taken for length-frequency analysis must faithfully reflect the size structure of the catch and, within the limits of gear selectivity, should reflect the true size structure of the population. The measured fish must be selected randomly or systematically. Generally for management surveys, the first 200 fish caught of each species should be measured to inch group, but very large catches should be subsampled so that a variety of sample sites and dates are represented. Lesser numbers may be measured if the range in fish size is unusually small. Avoid subsampling from catches held in tubs or other containers, as the subsample will almost certainly be biased. It is better to measure all the fish caught in every other net rather than to pool the total catch in a tub and try to randomly pick out half of the fish. Also, do not select specimens on the basis of size with one exception: the largest or the smallest specimen may be added to the length-frequency table if it was not included in the 200 already sampled. This allows the full range in size within the catch to be conveniently recorded. The length-frequency of the sample is to be reported on the FISH COLLECTION form. A rough draft of the form may be used for tabulating data in the field. 1. Length-biomass and total biomass. --Biomass of fish is a better measure of productivity and of community structure than numbers of fish. On the population level, a length-biomass table (FISH COLLECTION and POPULATION ESTIMATE forms) indicates at which size a species has accumulated its greatest net production--after that size the population loses more biomass to mortality than it gains from growth. On the community level, expressing species composition as a percentage by weight compensates for the large differences in the average lengths of the species. Obtain length-biomass data for the random sample of fish used for the length-frequency table either directly by weighing all the fish in each inch group, or indirectly (usually the most practical under field conditions) by multiplying the number of fish caught per inch group by an average weight for fish in each group. For the indirect method, obtain an average weight for each inch group by one of the following: 11-38 Rev. 1/85 1. Adding the empirical weights taken for the lengthweight relationship and dividing by the number of fish weighed (LENGTH-WEIGHT FIELD DATA form); 2. Calculating from the length-weight regression equation (or simply reading from the graph), by assuming the average length of fish in the inch group was the midpoint (e.g., 6.5, 7.5, etc.); 3. Using the state average length-weight tables (VI-A12). After the length-biomass table has been completed, species an average weight and the total pounds caught, statistics required for completion of the forms. calculate for each then the other Example: 80 perch (plus other species) were taken in two experimental gill nets. Of these, 68 were measured to inch group (shown) and 48 were measured to 0.1 inch and 0.002 lb. (not shown, recorded on a LENGH-WEIGHT DATA form). Average weights for the inch groups were: 5-inch, 0.060; 6-inch, 0.101; 7-inch, 0.149; 8-inch, 0.230; 9-inch, 0.312. Biomass estimates were obtained by multiplying each average weight by the number of perch in each group (e.g., for 5-inch group: 0.060 X 12 = 0.72 lb.). The table was then completed: Avg. Wt. = 12.08 lb./68 = 0.178 Total Lb.= 0.178 lb. X 80 = 14.24 %L-A No.= 41/68 = 60.3 %L-ALb. = 9.84 lb./12.08 lb. = 81.4 CPE No. = 80/2 = 40 CPE Lb. = 14.24/2 = 7.12 Species Gear Length Avg. Wt. Total CPE %L-A Inches 1 2 3 4 5 6 7 8 9 10 Sample Total Y. perch EG 7.6 0.18 No. 80 40 60 12 15 8 20 13 68 Lb. 14.2 7.1 81 0.7 1.5 1.2 4.6 4.0 12.0 Note the rounding off in the table. -39 0 ffI I m. Average length and weight. --Designated as size, no. and "size, lb.".on the FISH COLLECTION form. Calculate from a random or systematic sample, usually from the length-frequency and biomassafrequency tables. The best estimate of the average length of small samples of fish is the simple average of individual measurements which were made to 0. 1 inch. A satisfactory estimate of average length may be computed from a large length-frequency sample by a weighted formula which assumes that the 0-inch group fish average 0.5 inch long, the 1-inch group fish average 1. 5 inches long, etc. Each median length is multiplied by the number of fish in the inch group, the products summed, then divided by the total number of fish. Below is calculated the average length of the 68 perch in the preceding example (II-E2n). (5.5 X 12) + (6.5 X 15) + (7.5 X 8) + (8.5 X 2D) +.X3) avg. length=68.7.6 inches The best estimate of average weight is obtained by dividing the total biomass in the biomass-frequency table by the number of fish in the lengthfrequency table. See the example in II-E21. Alternatively, divide the empirical weight of the total catch by the total number of fish. n. Growth. --Samples taken for age and growth analysis should fairly represent the ages and growth rates within a species population. Subsamples may be taken from the catch systematically (e.g., every other fish), randdmly, or on a stratified-random basis (e. g., 15 randomly selected samples from within each inch group). The stratified-random method is best when the catch is large, when a length-frequency sample is also taken, and when age groups cannot be clearly identified in advance on the basis of length or stocking records. For most management surveys of growth a sample of 10-15 fish per inch group is adequate. That will usually result in a sample of at least 15 per age group. For more intensive studies of growth and age composition (as in conjunction with population estimates), a sample of at least 30 fish per -40 inch group should be taken (see II-Ep). Appendix VI-Al discusses general aspects of sample size in greater detail. It is better to take too many samples (not all of them need be examined) than too few. The techniques of scale sampling, aging, and back calculation are discussed in VI-A4. There are two methods for calculating the average length of an age group of fish. If the sample was taken systematically or randomly, then a simple average of the data is appropriate. However, if a stratified subsample was taken, a simple average gives an overestimate in most instances and it is better to calculate a weighted average length with the aid of length-frequency information, as illustrated in VI-A10. The method used for calculating average length is to be recorded in the space provided on the FISH GROWTH form. Statewide growth averages and computed growth indices (see VI-A4) may be used as standards for comparing the growth of one population with others. However, in judging if the observed growth is satisfactory or meets expectations, other factors such as the productivity of the water and the type of fish population should be considered. The state averages have been broken down into four time periods per age so that more meaningful comparisons can be made between samples taken at different times of the year. For example, age-Irn largemouth bass "should" average about 9.4 inches in January-May (prior to that growing season) and about 11.6 inches in October-December (after that growing season). If the observed length of age-III bass in Example Lake was 10.4 inches in May 1960 (growth index = +1.0), and 10.6 inches in November 1970 (growth index= -1.0), then it is clear that bass growth has declined (2.0 inches). o. Population estimates. --Estimates of the actual density of fish may be obtained by (1) a complete census of the entire water body or a portion of it, e.g., draining or poisoning followed by complete recovery; (2) catch per unit of effort adjusted for gear efficiency, e.g., catch per area seined, trawled, or electrofished; or (3) by one of the variations of the mark-andrecapture technique. Because complete recovery of fish is rarely possible and the efficiency of gear is difficult to assess, the mark-and-recapture method is usually the best. -41 Mark-and-recapture data of the Petersen type (e.g., trout in streams) may be submitted for machine computation by entering the raw data on the left-hand side of the POPULATION ESTIMATE form. After the estimates are computed, the rest of the table is to be completed and distributed. Estimates derived from other types of formulas (e.g., Schnabel) should be summarized on the same form, if possible. For details on mark-and-recaptured methodology refer to VI-A2 (streams) and VI-A3 (lakes) and to standard references such as W. E. Ricker's (1975) "Computation and Interpretation of Biological Statistics of Fish Populations, " Bulletin 191, Department of the Environment, Fisheries and Marine Service, Ottawa, Canada. Several points about mark-and-recapture estimates merit emphasis: 1. It is usually wise to collect scale samples during population estimates so that age-frequency and survival can be studied concurrently (see II-Ele and II-E2k). 2. They are highly recommended for management surveys of wadable streams because much better information is obtained for only about twice as much effort as a once-through electrofishing survey. The Bailey modification of the Petersen formula is the most appropriate. See II-B2c for specifics on length of stations. 3. They are more accurate (and sometimes less work) than a complete census of chemically treated waters. Mark native fish prior to the treatment and then examine a large sample of the dead fish to obtain the ratio of marked to unmarked fish. 4. They must be stratified by species and size, then summed, to compensate for gear (and people) selectivity. If possible, use one type of gear to catch fish for marking, another type of gear for the recapture sample. 5. The most critical underlying assumption is that marked fish have the same probability of recapture as any other fish in the population in the recapture sample. 6. Care must be taken to sample all parts of the study area. For example, use extra long electrodes to sample trout living in deep pools of -42 streams. Alternatively, conduct the estimates when the fish are mixing freely and are equally vulnerable to capture. Such mixing occurs on the shoals of lakes during spring and fall. 7. Valid estimates can be obtained even after a long lapse of time between marking and recovery (e. g., fall to spring), provided: a. Marks are not "lost". b. Marked and unmarked fish have the same survival rate. c. Fish are not subtracted or added to the population because of movement or recruitment. 8. Concentrate sampling effort on the target species. For example, in electrofishing wadable trout streams, concentrate on catching trout and do not attempt to make quantitative catches of other species (muddlers, minnows, suckers, darters, etc.) at the same time, because trout catches (and estimates) will suffer. Simply note if other species are abundant, common, or rare. If better population data are needed for these non-target species, then conduct a DeLury-type estimate (see Ricker [1975] for methods) in a short section of the stream. Example. --Brook trout in a stream were sampled with a 220-volt DC stream shocker. They were marked by clipping the top lobe of the caudal fin. Scale samples were taken. Field data from the marking and recovery runs are shown in Tables 1-4 and 11-5. In the office, the data were tallied, and population estimates were made by inch group using the Bailey modification of the Petersen formula (Table 11-6, see also VI-A2). It is better than the simple Petersen formula when sample sizes are small, as is typically the case. Direct estimates of the 1-, 12-, 13- and 14-inch groups could not be made reliably because fewer than three recaptures were made. Therefore, data for the 1- and 2-inch fish were combined and a single estimate calculated. For the large trout, it is apparent that nearly 100% of them were caught and the best estimate is simply the sum of the catch. Alternatively, we could have calculated the ratio of number of marked fish to the population estimate for every other size group, plotted these ratios versus size groups, fit a line or a curve to these points, read the ratio off the graph for the size group -43 Table 11-4. --Example of stream fish population estimate:.Mi 8 KIN R(A.J - 8RO'OK TROUT AtLEXAADER CREEK 81,30180 A. ~.. R1016-1 -- --- 4- 3 &-*1 F. 0 1 9o 9.0 /D. to20 i 33413.3 S4 44 S 16.3 6./( 7? i 5 3.0 /0.0 /1.0 /3.0 1j1o 3 ___ 431~.3 13.~ 13..3.0.3.4 JV..~'.s~ O 6s.3lI I1?.S 8.0 9.0 /0.0 u..4' 0./0.1.8 3 p1 36 J3.3 34 S? 17 f 1 44 S.1?. 0 4.& 1.0.7-1/Ato 3./I 3 1.,. 3.'16.313.'1/i35s '8 $b b (S- 1611 7 6 s oS C.3 1.0 /.3 3? 04.8 0.14.3.8 3.30 '1 s.s X~5 6.8 4.? 7.1 5.0 1/ /0.0 1.0 *73 1s04.S 47.8 J3.14 ill1.0 S,~8 ~.S"6.5 lo. 7.3 &J__ __ 3o.1i//v 3. a? 34 3.7 73.3 3.3 13.0 I1 IS.?IT'S6.3I 7.1 8.31 1.8 110.3 // -.2_0_ 23As.1V43' T.? v14.1 6-017.3 &a3 t 9.0 ___/ ls _____3.8.243.? 13 IS/ j3Ai 3 '1.8 0 65,.4 6.1 4 7.8 0 5 1. /0.7 _____J.-.. 9? 1 3i( ~ 6.4 63.83 7.3 19 - /0.2 ___x_8 3s 6&...8. 3.? 7.*1 /0.3 -sr 'p-4 2 ' ox -4 sA? ~5 1..2.3 3 9.0 /As.2.oS*.7r..4. J4.3.3.7 -S r 4.1 't3 3 _*3.3 3.7.8 1&3 J-2.0 12.3 1.S? -7 40 74 8S t 3 ___.3. 13.3 34 _ 3.02 3.0 '1. _ s,3 6.4G8 3.1 34 1.5 _ 3$ 1.7J 3 $8 4 UL J-0 1-8 =3 1 19-8sJ - 0.1.8 10-1 3._ ad_ %4 s_ 8.ly 3. 053,43.8 3. 3. P-.3.3.1 41.1. IT.5 4.3 R5 -r 0_to 1. 3.5.0 JA '1.3.oa I.3.0 -3-;2 r, 8 ___.43.5 3.?.3.43,3 14_ 5 6.52 t8o 9.a ~.j. 3.7I~ 3.3.3.1 '1. s1 4.3 85 % Ii ____31. 3 3.0 3.4~ 6.3/ t. 7.0 __ 33.42. 3.0 3,.5..TA.I ___. 9.4 j *__ 2,3.3...3S3. 3. 6. 1. - - 3.S $ -. 8.8 ~.. (31... 3.3 ~5 6.0 74 _.5r 13.0 3.7533 ~7S i.j/ 34 ~ 04. JS - - -- -----. -44 Table 11-5. --Example of stream fish population estimate: Recc.ovEPM Rm~v - l8,Roox 77qour R6.5)ANOESp.#1 ue ( 10 naIh 0 1n; n Oh et U = UA' (filmAKS6 IV = mA tiVCEzib R1016-1 LA m Lk vM LA. M LI A. 4 M L y __ J _.tJc+f/ff~ ~ ~ ~f H ____ ~~ ~~ ~~I K~ #1 _ 41 ~ _ _ _ _ -45 Table 1-w6. -*-*Example of stream fish (brook trout) population analysis. B3ROOK 1TAOuT PLX oRCREEK ~ScroNA R OEA 0,2;qf HA-) R1016-1 INCH14ROuP ___ l 3 d 5 /7 q? S/ /,a 13 1 --Maft-~Re c Prua PoptALTI N6 TI 'resS SA I _ _ v2 1,31 4 14 ~ 17 _a J /- I 3 3 7 R ECAPTREb 0 9D 10 4 a2 1 1012 a e 1 TooI-A CAH _M113,I /1 34 79 A 0 612.1 /a - 0 1 1 _____ ___1 _ 1" /O311 IIf/ al. 3s42 $..T.20 /Y 3.3 /I_ _a p Jnalbil off_017_~ 1 T IO $ 87 11 2O3.3 8 016j. 1341 1. PC F 4ALEZMM LIS BY.PERILNT ANOel F 113H J ___: 0 10 -___XS93__ j V. 7. 3 ~~~ a _____ Q~0)30) 00)u( 42 )) () kit)(6) (4) ( 2))();Ce 7.1 12T.01=61SA030 -31t /I zi _ _ _ _ta I 10 _ _ I9 ) - 93 )2.J n ln & IC )X19 AVbl)3ER A. N IJTH1 r AG6 GP~oDJP I~n 'L.j.-.. - ____:d. a ~ 90).3'SX~o)(*~c. 1. 4 ____1fl.S 'XIV +(wsJa: _______ ____~~O~.3'x(AI, 1 I - f3 aa i (eiL.. II _____ _ -46 with insufficient data, then expanded the number of fish marked by this ratio. Population estimates should be expressed in fish per acre, fish per mile, or fish per unit of discharge (Table 11-6). Biomass of the population should also be computed if the length-weight relationship is known. Using the age composition of the scale sample collection, the estimates by inch groups were converted to partial estimates by inch groups and age groups as shown in Table II-6. For example, of the 317 4-inch trout per hectare, 41. 7% were age 0 (132 fish) and 58.3% were age I (185 fish). The total estimate for the age group is then the sum of these partials. From the estimates by age groups just derived, the apparent survival rate of fish in the population was estimated. The survival rate is equal to the percentage of fish surviving to the next older age class, if recruitment is exactly the same each year. These rates were 32. 9% for age 0-I, 48.4% for age I-II, 10.2% for age II-III, 13.3% for age III-IV. A plot of the abundance of each age class on semi-log paper gives a graphic picture of survival rate (Fig. 1-5). Note the term "apparent" survival rate. This is because one cannot be sure whether decreases in numbers at a particular station are due to mortality or to movement out of the station which is why it is best to look at the population on a drainage basis. Good population estimates at all the sample stations of the drainage provide the means to estimate the population for the entire drainage. To do this, assume that the sampling station (located near the center of the drainage zone) is representative of the zone as a whole. Then calculate the population within each drainage zone by multiplying the population per acre found within the station, times the number of acres in the zone. To arrive at the population of the drainage, the populations of all zones are summed. From the data on numbers of fish in each age and size class, a weighted estimate of growth rate was made (Table 11-6). For example: the number of age-0 (fall fingerlings) in each size class was multiplied by the mid-point of that size class to arrive at total inches. This was done for each size class where age-0 fish were represented. Total inches were summed and divided by the total estimated number of age-0 fish to get the -47 4000 20001 1000 800 600 400 F 2001 - co a) I: 0. E z 100 80 60 401 - 201 10 8 6 41 - 2 1 I I.1 I I 0 I I I III IV AGE Figure 11-5. --Example of a survivorship from a stream population estimate. curve for brook trout -48 average size of age-0 fish. The procedure was repeated for each age group. Another example is provided in VI-A10. This method reduces most sampling bias but has limitations in that it requires rather extensive data. A graphic picture of the growth rate is in Fig. 11-6. p. Age-frequency and survival. --Age-frequency information may be used to simply identify weak and strong year classes or, more rigorously, to compute survival rates. Routine management surveys of growth often collect adequate information to rank the relative strength of year classes (note that stratified subsamples must be weighted as in VI-A10), however careful planning and larger samples are needed for reliable estimates of survival. For most purposes, studies of survival should be made in conjunction with population estimates. Obtain at least 30 scale samples per inch group. Methodology is presented in detail in II-E3o and VI-A10. The computations are to be summarized on the POPULATION ESTIMATES form. Survival may also be estimated from simple "catch curves " by substituting catch frequencies for mark-and-recapture population estimates. See textbooks for discussions of methods and limitations. This method is not as reliable because catch frequencies are biased by gear selectivity. Estimates of annual survival rates based on age frequencies taken on one date (whether based on mark-and-recapture estimates or simple catch curves) are subject to errors caused by uneven year class strength. Therefore, it is best to estimate the population in two consecutive years and compute the survival of each year class directly as the number alive in year 2 divided by the number alive in year 1. For an example of the computation of survival rate see the trout data in the preceding section (II-E3o). q. Production. --Production, the result of the interaction between growth and mortality, is useful for computing maximum sustainable yields and in selecting the most appropriate fishing regulations. It is narrowly defined as the total elaboration of fish tissue during any time interval (usually a year), including individuals that do not survive to the end of the interval. It is obtained by multiplying the instantaneous rate of increase in -49 14 - 12 -10 -^8 -0 8 c4 -2 -0 I II III IV AGE Figure 11-6. --Example of a growth curve for brook trout from a stream population estimate. -50 individual weight by the average biomass of the population during the time interval. Thus, the basic data required are growth, survival, and the biomass of the population. Production can be determined by means of a graph (Allen method), equation,, or computational table. See references such as: W. E. Ricker (ed.) 1968. Methods for assessment of fish production in fresh waters. IB? Handbook No. 3. Blackwell Scientific Publ., Oxford and Edinburgh. r. Natural history observations. --Record field observations on fish movements, spawning,, disease,, parasites, etc. on FISH COLLECTION or NOTES AND REFERENCES forms. These observations are important., If a number of fish have disease or unusual features, make accurate observations and count and weigh them. Save some specimens on ice for later examination by a pathologist or other specialist. E. Fishery assessment Observations on the fishery should be recorded on the FISH COLLECTION or NOTES AND. REFERENCES form. Recorded observations should usually be limited to fish observed; however, local reports of success or complaints may be recorded if the biologist feels the account is reliable. Creel census should be used to document the success of significant management, programs. Creel census methods are contained in VI-A9. Assistance in conducting a creel census is also available at the Institute for Fisheries Research in Ann Arbor. III III. GEAR Gear for collection of fish samples continues to develop. The most common types of gear are described in the following sections. Consider these descriptions as standards--gear with other features must be more fully described on the FISH COLLECTION form. Whenever you collect samples make sure the gear is adequately described so the biological information will continue to be useful and collections can be duplicated later. New gear or techniques are sometimes needed, use your training and experience to the fullest. A. Trap nets Description There are two types of trap nets in use for inland surveys; the "3-foot trap" and the "6/3-foot trap. " Walter Crowe developed the 3-foot trap and Dave Havens the 6/3-foot trap. Figures IIl-1 and III-2 describe these traps. Use Trap nets are effective in lakes. They readily take most of the warmwater species and trout if they are actively moving. Size selectivity is determined by mesh size and size of the funnel opening. Trap nets usually allow return of fish to the water unharmed. Trap nets fish best when set off points, weed beds or other obstructions to fish movements which act as natural leads. Nets are usually set perpendicular to shore, on a gently sloping bottom, with the pot end deeper than the inshore lead. They do not fish as effectively on steeply sloping bottoms or in depths greater than about 10 m. Trap nets should be fished one night between lifts. -2 LEAD is 3' high 100' long with 2Y2" stretch mesh NYLON MESH and POLYPROPYLENE ROPE O Figure IH-i. --Construction details of a 3-foot trap net. -3 7 opening POT has 1Y2" stretch mesh HEART and WINGS have 2" stretch mesh Figure III-2.--Construction details of a 6/3-foot trap net (~-foot lead tapering to a 3-foot pot). * q 111-4 Rev. 1/82 B. Fyke nets Description The original design has 2-inch stretch mesh, is 4-feet high, and has a 150-foot lead (Fig. 111-3). The same frames are sometimes hung with either 1 1/2-inch or 1-inch mesh, and fitted with shorter leads. A fourth variation has I/2-inch mesh, a 25-foot lead, and a half-scale frame (2 feet high X 3 feet wide). In describing fyke nets on forms, record stretched mesh size and frame height. Use Fykes are easier to handle than trap nets, especially in water less than 2 m deep. They are effective in lakes and in sluggish rivers. Selectivity is influenced by mesh size and fish movements. Fyke nets should be set perpendicular to shore or with the current. They fish better than trap nets on steep slopes. Fykes should fish one night between lifts. They can be substituted in place of some trap net sets. C. Inland experimental gill nets Description This net is 125 feet long and 6 feet deep. It consists of five 25-foot sections of different mesh sizes. The mesh sizes (stretch measure) are 1 1/2 inches, 2 inches, 2 1/2 inches, 3 inches, and 4 inches, and are hung in that order on a 1:2 basis (2 feet of stretch mesh per foot of lead or float line). The mesh is made of nylon multifilament. Weight of the solid core lead line should be sufficient to sink the net. Use Gill nets are used in lakes or (very carefully) in sluggish streams. Gill nets are very selective, but effective in catching many fish, especially yellow perch, northern pike, and trout. Centrarchids are usually undersampled. Gill nets are to be fished one rtight between lifts for standard CPE. Set each net as an individual unit. -5 MESH #15 Ny 2" St Top View B-n A 4' x 150' Lead 8" Opening 10' Opening A* flon retch 4 A A B B Hoop Front Frame Y2 Thin wall conduit Figure I111-3. --Construction detail of a fyke net. -6 D. Modified Great Lakes gill nets Description This net is 500 feet long and 6 feet deep. It fishes on bottom. It consists of ten 50-foot sections of different mesh sizes. The mesh sizes (stretch measure) are 1 1/2 inches, 2 inches, 2 1/2 inches, 3 inches, 3 1/2 inches, 4 inches, 4 1/2 inches, 5 inches, 5 1/2 inches, and 6 inches, and are hung in that order. Material is nylon multifilament: #46 (210/2) for 1 1/2- to 3 1/2-inch mesh; #69 (210/3) for 4- to 5 1/2-inch mesh; and #104 for 6-inch mesh. The mesh is hung on a 1:2 basis with double selvage. One lead and one float per 8 feet of net. Leads weigh three per pound. Use This net has been used in larger lakes where a large sample is needed or where larger individual fish are fpund. Gill nets are to be fished one night between lifts. Set each net as an individual unit. Number of sets must be tailored to the survey needs. E. Seines Description Various seines are in use. There seems to be no "standard" seine. Use Generally, seines are effective on small fish, especially minnows. Larger seines are effective in sampling most species which occur in habitats within "reach" of shore if the habitat is free of snags. Enough effort should be expended to obtain a representative sample of fish. Sample sites should be widely scattered. I -7 F. Toxicant sampling Description Toxicants may be used for total or partial reclamations (with approval) and for obtaining samples of fish. Currently, only rotenone and antimycin A are approved for use by the FDA. Safety precautions must be followed. Various methods can be used. A description of the procedure used for cove sampling by the Texas Parks and Wildlife Department follows: Place a barrier net of 1 1/2-inch stretch mesh across the cove one day prior to treatment. Bundle the net along the float line to permit free passage of fish. Release the net sometime between 2 hours after sunset and 2 hours before sunrise during the night before treatment. - Place marked fish, similar to the species in the lake, into the area. Use enough toxicant for a total kill. Begin treatment on or before 8 AM. Recover fish on the day of treatment and the following day. Use Sampling with a toxicant has been a valuable tool in many states and has been used on large rivers in Michigan. When marked fish are present, more accurate estimates of the composition of the fish community and of standing crop can be made by means of size-stratified mark-and-recapture methods. Toxicants sample all sizes and species of fish but not all sizes and species are recovered with the same degree of effectiveness. Enough effort should be expended to obtain a representative sample. -8 G. Electrofishing Description There are two basic kinds of electrofishing gear, "boom" and "stream, " but many variations. Power supplies and configurations vary greatly and must be adequately described on FISH COLLECTION forms. "Boom" shocking equipment, used on lakes and large rivers, consists of a boat rigged with booms out front. From two to five electrodes are suspended from the booms. IF DC current is used, the positive electrodes (usually two) are out front and the negative electrodes trail along the sides (see Novotny and Priegel 1974, Wisconsin Tech. Bull. 73). Common types are 220-volt, AD, DC, or pulsed DC. Working output is normally 4 to 10 amperes, but it should be adjusted to water conductivity, size of fish, and fish recovery time to avoid injury to the spine or to. the gills. "Stream" shocking equipment, used on wadable streams, may be either of the pulsed DC "back-pack" battery type, or the type which requires the use of a small boat to transport the 220-volt DC generator. The latter supplies more power and is much more effective. The positive electrode (1, 2, or 3 may be used) is hand-held; the negative electrode may be attached to the bottom of the boat or to a separate float. Use Electrofishing gear is less size selective than fyke, trap, or gill nets and obtains a more representative sample of the size structure, age structure, and growth of the population. However, its use is restricted to shallow habitats less than about 1. 5 m deep, and that may result in a sample which is unrepresentative of the water body as a whole. Electrofishing is the most effective gear for sampling stream and river fish. It can be effective in lakes for routine sampling, or for special projects such as sampling bass in the spring or trout in the spring or fall. Some fish, such as northern pike, often escape from the electric field. In lakes, usually a larger and more repres'entative sample of fish -9 is obtained after dark. Catch may vary greatly seasonally, and from night to night, depending on fish movements. For boom shocking rivers, it is usually best to fish downstream, motoring slightly faster than the current, but pausing occasionally to allow fish stunned on the bottom to drift to the surface. A minimum amount of effort is 15 minutes of actual fishing time. For routine inventories, permanent stations should be established and recorded on a map of the lake or stream. On small lakes, the entire shoreline may be covered; on larger lakes, select as many areas as necessary to sample all habitat types. Water conductivity should be measured for each survey. H. Trawl Description A 16-foot head rope otter bottom trawl is standard for inland sampling. The trawl is 16 feet across the front opening and has 1 1/2-inch stretch nylon mesh on the main part. The cod end has a liner of 1/4-inch mesh. Otter boards with adjustable chains are used to hold out the sides. The foot line is weighted with chain and the head line is fitted with styrofoam floats. The net is fished with a boat with at least a 20-hp motor and pulled by hand or winch. Towing speed is measured using a simple trolling meter. Towing lines must be long enough to maintain the trawl on the bottom. Use Trawling is similar to bag seining, but more mobile and can be used in deeper water. Minnows and young fish are the main targets, but fish as large as adult perch are sampled. m10 Several tows in each area are more meaningful than single spot tows., Where possible, tows should be 5 minutes long. Record time from when the trawl is started along the bottom to when you start to pull it in. I. Visual observations Description Visual observations of spawning fish., unusual c once ntrations,, movements., etc.,, are sometimes made. This ca n be done on calm day's or at night with the aid of a, light. Use Observations may pinpoint the optimum time for population control or spawning habitats. 6 >* IV-1 IV. FORMS--USES AND POINTS OF CLARIFICATION Forms dealing with surveys are listed and briefly described in this section. Only items which are new or likely to be confusing to users are discussed in detail. For additional clarification, refer to related sections of the manual and to the examples provided. One new item, appearing on several forms, is "Id.. " This item is to aid computer storage of information in the future and need not be filled in at present. For lakes, the identifying county and lake number are given by Humphrys and Green in the "Michigan Lake Inventory Bulletin. " For example, Houghton Lake's Id. is 7278. For streams, the Ids. will be designated in the Watershed Management Plan. SURVEY PLANNING FORM R-8060). Use to plan all surveys. The purpose of this form is to assist in review of past surveys, setting an objective for the proposed survey and communicating this information to others. Dispose of the form after the survey report is completed. LIMNOLOGY(E-8056). Use to record the results of water analyses and observations on vegetation and weather conditions. Most requirements are self explanatory. Two columns are available for temperature-oxygen depth profiles. These can be used for two stations if desired or one station if the lake is exceptionally deep. One station located in the deepest part of the lake is adequate unless the lake consists of two or more distinctly separate basins. Wave condition--recorded as calm, choppy, rough or white caps. These designations give a better indication of the effect of wind on the lake than simply recording wind velocity. Maximum depth of vegetation--in most lakes it is possible to see the maximum depth of vegetation growth. The actual depth at the -2 line of demarcation should be measured with a sounding line or an echo sounder. If plants are not easily seen, the limit of growth can be determined with a plant hook or rigged substitute. Percent shoal--defined as the percentage of the total lake area shallower than 5 m or 15 feet. Measure on a hydrographic map of the lake with the aid of a planimeter or grid. If the map contours are given in 5-foot intervals, use the 15-foot contour; if the map is scaled in meters, use the 5-m contour. Chlorophyll a--and nutrient concentrations--will be analyzed by the Environmental Services Laboratory from our water samples. The data should be recorded on the LIMNOLOGY form as they are made available by the lab. Record the depth at which "mid-depth' samples were collected for nutrient analysis. Pollution--record any pollution observed. The "comments" should include a statement as to remedial steps being taken or whether a report has been made through proper channels. Vegetation--aquatic vegetation will be classified as to type (submergent, emergent, floating, Chara), and ranked in abundance as: none, sparse, common, abundant, or excessive. A designation of excessive should indicate nuisance conditions that interfere with recreational uses of the lake. It would also be probable that there had been frequent public complaints and requests for control programs. The observations required here will give an evaluation of the abundance of various types of vegetation throughout the entire littoral area. For each type of vegetationlist a combination of percentage and abundance designations to equal 100% of the littoral area. For example, submergent weeds might be excessive throughout 50% of the littoral (50E), common in 20% (20C), and sparse in 30% (30S). The entire designation for "submergent" would thus be: 50E, 20C, 30S. Give similar designations for all other vegetation types, even if some types are absent in the lake (Example: Floating 100N). -3 Additional comments--observations worthy of comment might include (but not be limited to): 1. Sensitive areas to be protected: marshes, spawning shoals, etc. 2. Evidence of dredge or fill or other perturbation. 3. Residential development; percent developed, whether septic tanks or sewers, etc. 4. Immediate watershed; percent in agriculture, forest, old field, residential, urban, etc. 5. Existing or potential erosion problems. 6. Potential for water quality management or rehabilitation. INLAND LAKE MANAGEMENT UNIT FORMS. FIELD SHEET. This form is used by the Inland Lake Management Unit for their intensive lake surveys. It is imperative that they have all required field information. If water analysis data are not accompanied by precise field information (station locations, etc.'), none of the data-will be accepted by STORET. ENVIRONMENTAL LABORATORY ANALYSIS--BIOLOGICAL (ESD-02602) ENVIRONMENTAL LABORATORY ANALYSIS--IN ORGANICS (ESD-04000) ENVIRONMENTAL LABORATORY ANALYSIS--ENVIRONMENTAL QUALITY (ESD-01403) At the present time the Environmental Services Laboratory is divided into several units, each requiring separate samples and analysis forms. Analysis required for a second level limnological survey will utilize the services of three units of the laboratory, and thus require three water samples and the completion of three laboratory analysis forms. Changing analytical methodologies frequently result in changes in required sample size, preservation, etc. Appendix VI-A-16 contains information concerning sampling requirements, and completion of forms required by the Inland Lake Management Unit. The laboratory may also be contacted by phone for additional information. IV -4 Rev. 1/82 LAKE PHYSICAL DESCRIPTION (R-8057) Summarizes information from various sources on the physical characteristics of lakes. Line items 1-5 are to be completed from available maps and reference materials listed on the form (data for lakes larger than 100 acres are available now), other lines are to be completed by on-site surveys. Update form every 20 years or when new information becomes available. LAKE AREA AND VOLUME ANALYSIS (R-8069). Use for calculating the area and volume of lake from its hydrographic map. See appendix VIA6. FISH COLLECTION 0--8058) and FISH COLLECTION (CONT)8058-1). Intended primarily for distribution and permanent file storage, but may be adopted for use in the field as well. Use for fish collections from lakes, rivers, or streams. Summarizes information on sample site(s), year, catch, CPE, LENGTH-FREQUENCY, and LENGTH-BIOMASS. Extensive space is provided for maps, analysis, and comments. Not every item of information requested is relevant to each survey. These forms may be used in four ways to summarize catch: a. By gear type, for all collection sites. A compulsory use. More than one kind of gear may be listed sequentially on one sheet, as illustrated. Distribute copies. b. For all gear types, for all collection sites. An optional use in addition to (a). May be put on the same sheet as (a). Distribute copies. c. For an index station. Retain in District file unless of wider interest. d. By individual collection site or net set. Retain at District unless of wider interest.. Side 1 Sutmmarv of- -indicate source of the information on this form, i.e., site and gear. IV-5 Rev. 1/82 Sample site(s)--indicate number of locations, range in depth at which the gear was fished and (if the water was thermally stratified and contained dissolved oxygen) the temperature range where the gear was fished. If water temperature was uniform from surface to bottom, record only the surface temperature. Sample location(s)--describe, or use space given for sketching a map. Cover--rank the abundance of cover (none, sparse, moderate, abundant) and describe the type (vegetation, undercut banks, logs, etc.). Fish foods--comment on foods observed in the habitat or in fish stomachs. Water clarity and level--refers to conditions which might affect gear efficiency (especially electrofishing). Conductivity--express in micro ohms per cm2. Record temperature elsewhere on form. - Electrofishing efficiency--either rank as poor, satisfactory, or good; or for mark-and-recapture studies, give the recapture percentage on the second "run" i.e., number recaptures divided by number of recaptures plus unmarked. Stream physical data--it is recommended that length, average width, average depth, average velocity and discharge be determined by the methods in Section IIB2. If those methods are not followed, prefix the estimates with "approx. ", as illustrated. When a current meter is not available for the proper determination of average velocity, use "the wood chip method" and record the result as "surface velocity. " Bottom type--primarily intended for stream surveys but may be used to describe lake sample sites too. Estimate the percentage of bottom comprised of bedrock, boulder (greater than 10 inches), cobble (3 to 10 inches), gravel (1/8 to 3 inches), sand, silt, clay, muck, detritus. Gear--list the number of units used, types, unusual features (see description of standard gear in Section III) and, for trap and fyke nets, IV-6 Rev. 1/82 height and pot mesh size (stretched). For example: 5 exp. gill; 1 G. L. gill; 3 gill 100 ft>( 8 ft X 1 inch suspended at surface; 2 traps 3 ft X 1 1/2 inch; 7 traps 6/3 )K 1 1/2 inch; 3 fykes 4ift X 1inch; etc. For electrofishing gear give AC or DC, voltage, amperage, number of electrodes, and day or night operation. For seines, indicate length, height, and stretch mesh as follows: seine 50 ft X 6 ft> 1 inch bag. For recording fishing effort, code gear as: T trap, F = fyke, EG = experimental gill, GLG = Great Lakes gill, E electrofishing, S = seine, and TR = trawl. Develop and define other codes as needed. Effort- -standard units of effort are given in Table II-3. For net lifts, record the total number of lifts which were fished one or more nights (e. g., four nets lifted once a day for 3 days = 12 net lifts; four nets lifted every third day = 4 net lifts). For net nights, record the total number of lifts which were fished one night (net nights = net lifts if the nets were lifted once a day; net nights = 0 if four nets were lifted every third day). For area covered, record the acres seined, trawled, or electrofished (for streams). For hours shocked, record actual fishing time in lake or stream (optional) electrofishing. Non-standard types of effort, such as nets lifted more than once a day, should not be recorded here but may be noted under Analysis, map, remarks, fishing reports. Standard effort which is not representative (for example a torn net) should be footnoted and explained and CPE should not be calculated from it. purpose of collection- -state the survey objectives or why it was done (e. g., reports of poor fishing, basic inventory, survey of walleye recruitment) to aid in the interpretation of sampling methods and results. Data collected- -indicate the types of data gathered during this collection and the resulting summaries which were prepared. The CATCH SUMMARY and LENGTH-FREQUENCY and LENGTH-BIOMASS summaries are on the FISH COLLECTION form; the other summaries appear on other forms. IV-7 Rev. 1/91 Analysis, map. remarks, fishing reports-Use this space for (1) commenting about gear, methods, condition, and disease of fish, etc.; (2) a map of sample sites; (3) analysis and interpretation of the collection; and (4) reliable fishing reports. Side 2 (See Section H, pages 25-26 and 27-39). Lengh-Record average length or range in length (to 0.1 inch). Avg. Wt.-Total lb + No., or from LENGTH-BIOMASS sample. Round to 0.001 lb. Total-Total catch, by species and gear, in both numbers and pounds. Total pounds may be obtained by weighing all fish, or calculated from the LENGTHBIOMASS sample. Round pounds to nearest 0.1 when <50; to whole pound when >50. Total %-For each type of gear: total number (and pounds) caught of each species + ALL SPECIES TOTAL x 100. Round to whole number when >1%. CPE-In terms of both numbers and weight. Standard units of effort are net lifts (overnight sets); area (in acres) for seine, trawl, and stream electrofishing; time (in hours) for lake electrofishing. Round to 0.1 when <20; to whole number when >20. Percent L-A-Percentages of the LENGTH-FREQUENCY and LENGTHBIOMASS samples which were of legal or acceptable size. See footnote on form for definitions. Space is provided on the bottom of the form for alternative definitions. Round to whole number when >1%. LENGTH-FREQUENCY-Measure to inch group all fish caught, or sample the first 200. Record numbers of fish in each group in "No." column and total number in sample at bottom of column. LENGTH-BIOMASS-Determine the weight of fish in each inch group of the LENGTH-FREQUENCY (see II, page 37 and Appendix 12). Record as pounds under "Lb" column, rounding to 0.1 when <50 and to nearest pound when >50. Sum to obtain sample total pounds and divide by sample total numbers to get an average weight for the fish collected. ALL SPECIES TOTAL-Grand total for the gear in numbers and pounds. -8 LENGTH-WEIGHT FIELD DATA(f-8059). Intended primarily for field use for recording the lengths and weights of individual fish, or of small lots of fish. Add appropriate headings and calibrate as needed. Space is provided for computing average weight by inch group, as an aid in calculating biomass estimates for the FISH COLLECTION form. Data recorded on scale envelopes in the field may be added to the form. The form may be submitted for computer analysis of the length-weight relationship. The information recorded on this sheet is to be summarized on FISH COLLECTION and LENGTH-WEIGHT REGRESSION forms for distribution and permanent storage. The field sheet may be stored by the collector. LENGTH-WEIGHT REGRESSION(R-8059-1). A summary form for distribution and permanent storage of the length-weight relationships of species taken in a fish collection. The conventional units of measurement at present are inches and pounds..Give the regression -equation on the front of the form, or plot the relationship on the log-log graph on the back of the form. The regression equation may be calculated by hand, or by computer from the LENGTH-WEIGHT FIELD DATA form t-8059) or the SCALE SAMPLE ANALYSIS form (R-8055). SCALE SAMPLE ANALYSIS R-8055). A work form for computer analysis; not intended for distribution and filing. To use, transfer data from scale envelope, add age and, if desired, scale measurements for back calculation. The computer will compute length-weight regressions, scale radius-fish length regressions, and will back calculate length of fish at each annulus. These data are to then be transferred to appropriate summary forms, distributed, and filed. FISH GROWTHR-8070). Summarizes the ages of fish taken in a FISH COLLECTION and compares them to statewide averages. Give a terse description of the collecting gear (more detailed information will be on the FISH COLLECTION form) and unusual methods. Examples: a random or complete sample of the catch instead of the usual stratified random size-selective sample; ages determined from otoliths, fins, etc., -9 instead of scales; selection of key scales or scales from areas of the body other than the recommended areas; weighted mean lengths (see VIA10) instead of simple averages; etc. See VIA4 for the state average growth rates and the method for calculating growth indices. Note that space is provided for analysis of results. POPULATION ESTIMATESa4-8073). Use to summarize for distribution and filing, data derived from mark-and-recapture population estimates of fish. The left-hand table of raw data may be submitted first for computer computation of Petersen-type estimates, then a final summary prepared. As a summary; the form provides space for (1) raw data, (2) estimates by inch groups, (3) estimates by age groups, and (4) survival rates. Items 3 and 4 should not be attempted unless the data are adequate (see IIE2j and IE2k). The form is set up for one species per side but more could be inserted. Sum--the sum total of the inch group estimates, except that the 95% limits on the sum of the estimates is not simply the sum of the limits on the inch group estimates. See appendix VIA2. Survival--round off to 0.1% (e. g., 4 7.3) Estimates, lb. --obtain for each inch group by multiplying estimated number by average weight, then summing. NOTES AND REFERENCES 0-8077). Use to record any valuable information not contained on other forms. LAKE SURVEY SUMMARY a-8063). Use for summarizing physical, biological, and fishery information about lakes. Most items on form are self explanatory; items 20 and 23 are explained below. 20. Oxygen-thermal types are based on mid-late summer oxygentemperature profiles and history of winterkill: 1. Stratified lakes with at least 2 ppm DO at all depths. 2. Stratified lakes in which DO falls from a high level to 2 ppm in the hypolimnion. -10 3. Stratified lakes in which DO falls from a high level to 2 ppm between the 2-meter level of the thermocline and the top of the hypolimnion. 4. Stratified lakes in which DO falls from a high level to 2 ppm between the bottom of the epilimnion and the 2-meter level of the thermocline. 5. Unstratified lakes in which surface temperatures exceed 22* C. 6. Unstratified lakes in which surface temperatures do not exceed 220 C. 7. Lakes subject to frequent, severe, fish kills (DO falls to near zero throughout the lake). 23. Vegetation--use ranking system for LIMNOLOGY form. STREAM SURVEY SUMMARY (a-8064). Use for summarizing physical, biological, and fishery information about streams. Most items on form are self explanatory or are explained in the text (IIA2). Items 2 and 3 are explained below. 2. Stream--name the stream on which the study station is located. 3. Drainage system--name the streams and rivers (in downstream order) traversed by water passing through the study site on its way to the Great Lakes. Example: Stream--Butternut Creek Drainage system--Butternut Creek, Fish Creek, Maple River, Grand River. MANAGEMENT RECORDS-8076). Summarizes management recommendations and actions. r S S VW&1 Rev. 5/91 V. REPORTS A final report is required for extensive surveys in addition to properly prepared forms. ItZ will be used for departmental and public information. Make and distribute a NOTE AND R.EFERENCE f orm ref erring to reports not stoared in the lake or stream f iling system. Refer to Fisheries Division Policies and Prý.ocedures f or additional inf ormati.on about report policies, and review and editing procedures. A. Style Reports can take the f ollowing forms: 1. Technical Report series -- f or inf.Lormatýion of stat-ewide intereset. River rcotenone surveys wi-ll be included in the t6h~is series, with contentýs as outz.lined in B. See Policies and Procedur,:es for Reports and Publications. 2. Status of the Fishery Resouro-#,.e Report series -- simila.r t66o Technical Reports, but'- less extensive distribution, including Dist%.-rict, Region, Division Office, and Research. Narrative style, as outlined in C. 3. Notes -- on FISH COLLCTION form or NOTES AND REFERENCE form* S V-2 Rev. 5/91 B. Content of River Rotenone Survey Reports Use the style and format of Towns (1987), Technical Report 87-3. The following outline, based on that document, is recommended: I. Summary. II. Introduction. III. Methods. IV. Results. A. Overview. B. Fishery description, by station. V. Discussion. A. General. B. Management considerations. VI. Literature Cited. VII. Tables. Table 1. Locations of sampling stations. Table 2. List of species captured at each station. Table 3. Percent of catch by weight, number and species. Chubs, shiners, minnows, darters, and individuals less than 3 inches long are excluded. Table 4. Catch results. Table 5. Numbers of common fish per surface acre collected at each station. VIII. Figures. Figure 1. Map showing locations of sampling stations. Figure 2. Weight of gamefish, redhorses and suckers, carp, and all fish captured at each station. *voV 3 Rev. 5/91 C. Content of Status of the Fishery Resource Reports Use the style and format of Dexter (1991), Status of the Fishery.Resource Report 91-1 for Deep Lake, with the associated Management Plan (copy follows page V-12). Framework software is available to simplify the preparation of report outlines and tables. outline The following outline is recommended. A description of the suggested contents of each item appears after this outline. I. Environment. A. Location. B. Geology and geography. C. Watershed description (inlets, outlets, connecting waters, basin and the associated Great Lake). Do Chemical and physical characteristics. E. Development, public ownership, and access. II. Fishery Resource. A. History of the fishery. B. Current status of the fish community. 1. Sumimary tables. C. Analysis and discussion. III. Management direction. A. Current. B. Goals and expectations. C. Obstacles to attainment of goals. * V-A Rev. 5/91 Comments On Prepazing-Status of the Fishery Resource Revorts These reports are to describe and analyze the current status of the fishery 'in this water body, using the results of the most recent survey of the fish community. They are to be placed in the context of the environment, the history of the fishery, and the management goals for the fishery. These reports provide a summary and brief review of fish, fishing, and management for biologists and for the public. Write in plain English and avoid technical jargon which would not be understood by most anglers. Almost all the inf"Lormation and data required for these reports should already appear on forms prepared according to the Manual of Fisheries Survey Methods. Status reports basically present the information on those forms in narrative style, with summary tables. Formulation of the management goals will require some additional thoughtful consideration of the water body and the fish community. The logic leading to the management goals should be clear, and the supporting facts and observations should appear in the previous sections of the report. The management goals must be consistent with the goals of the Fisheries Division. These reports should be updated following all surveys of the f ish community., The year of the fish survey should appear in the title; the date of the report's preparation should appear following the text of the report, just before the tables. V-5 Rev. 5/91 The common names of fishes should follow the guidelines of the American Fisheries Society (AFS); see AFS Special Publication No. 12, A List of Common and Scientific Names of Fishes from the United States and Canada, Fourth Edition. Outline Contents Here follows the recommended outline, with a description of the suggested contents of each item in the outline. I. Environment. Most of this information may be found on the following survey forms: Lake (or Stream) Survey Summary, Lake Physical Description, Lake Area and Volume, and Limnology. These forms are descibed in the Manual of Fisheries Survey Methods. A. Location. Be sure to mention the distance to the nearest town. B. Geology and geography. Briefly relate the information on geology and geography to aquatic systems. For example, the presence of sandy soils suggests a potentially large influence of groundwater on the water temperature and chemistry of a lake or stream. C. Watershed description (inlets, outlets, connecting waters, basin, and the associated Great Lake). D. Chemical and physical characteristics. E. Development, public ownership and access. II. Fishery Resource. A. History of the fishery. Describe the fish stocks and the fishery as they were in earlier years along with known problems and management history. B. Current status of the fish community. Describe status of the fish community and the fishery, * V-6 Rev. 5/91 environmental conditions, and resource uses including conflicting ones. Most of this information should be found on the following forms descibed in the Manual of Fisheries Survey Methods: Fish Collection, Fish Growth Analysis, and Population Estimates. 1. Summary tables. These tables summarize the species of gamefish present, their size, growth, relative abundance, and ages. C. Analysis and discussion. Analyze the fish stocks, the fishery, and the physical/chemical environment. Compare their current status with what they were in the past. All major species should be mentioned, including species which require no current actions. Also, this water should be compared with similar waters, and these fish stocks with others in the state (or with statewide averages). This discussion places the known information about the water in perspective and lays the groundwork for long-range goals and expectations. III. Management direction. A. Current. In addition to stocking or other actions, management will generally involve attention to habitat and water quality, and continued monitoring of fish population status. B. Goals and expectations. Describe what the status of the fishery could and should be in the far future (next 25 years). The success of all future management efforts will be measured by how much they move the fishery toward the goals set down here. Use the history of this water and performance of siiarwtrsadcomparable saewaters as a guide t setting long-range goals for the fish stocks, the 0 V-7 Rev. 5/91 fishery, and the environment. Consider natural reproduction, growth, standing stocks (by age and size), species mix, access, and public use as factors in making a goal statement. Note that the relative health of the fish stocks and the fishery can be measured by how close the current status is to the long-term goals and expectations. On many of our best waters our long-term goal (or a major part of it) will be to maintain the excellent health of the fish community and the environment. C. Obstacles to attainment of goals. List, in logical sequence, the obstacles (impediments and problems) that stand in the way of improving the fishery from its current status toward the expectations or vision for the future. This list sets the stage for the development of management objectives (described in the Management Plan, Section VI) and management prescriptions (set down on prescription forms). Example: "Excessive fishing mortality on bass and bluegills." IV. References. Cite references in the usual scientific report format. V. Hydrographic Map. Include a map if one is available. It must be legible and neat. It need not show survey sites. VI. Management Plan. This section starts on a new page, because it may not always be distributed with the rest of the status report. This appendum is required when extensive management activity is planned. It elaborates on Management Direction, giving proposed solutions to specific problems. See the example Management Plan for Deep Lake. One to several prescriptions may be based on this plan. *A. Objective. Objectives must be specific and have measurable end * V-8 Rev. 5/91 points. There may be several per goal. Example: "Reduce angling mortality of adult smallmouth bass from 0.50 to 0.35 by 1995." B. Proposed management action. Give a more detailed description of proposal. For example: "Delay opening day on bass until the last Saturday in June and raise the size limit to 14 inches." C. Expected results. Make your best prediction of the outcome of the action. A quantified expectation, even an educated guess. For example: "About 25% of the trout will be harvested by anglers, resulting in an annual harvest of 100-200 trout from this 100-acre lake." D. Evaluation. State how you plan to evaluate the management action. ~ For example,: "We will evaluate trout fishing from voluntary angler reports and will evaluate trout survival and growth via a tagging study beginning in 1994." Tables The format for each table is shown in the example status report for Deep Lake. Table 1 is included to show the species collected, their relative numbers and weights, and information about fish sizes. Table 2 indicates the growth rate for important species, with the corresponding Michigan growth index for comparison. Table 3 shows the estimated age composition of the population. If the sample is large enough, the mortality rate of the older fish can be estimated from this table. It should be apparent from this table whether or not strong and weak year classes are present in a population. Note that table entries are not simply the age frequency of the aged fish, but are values calculated for the entire population. Age frequency is computed by multiplying the number caught in each inch group S by the proportion of each age class found in that inch group, and summing over inch groups to get the total number of fish of each V-9 Rev. 5/91 age; the number in each age class is then converted to a percent of the total number of that species. See Mamual of Fisheries Survey Methods, Appendix VI-A-10, for an example. Framework software is available to aid in table preparation. Starting with a computerized version of the FISH COLLECTION FORM and scale sample data, rough drafts of Tables 1, 2, and 3 can be easily generated. Alternatively, use spreadsheets outliSRl.FW3, outliSR2.FW3, or outliSR3.FW3 as typing tables. S 0 0?idMu~iga mww Depotmt f Maniu Rwl Stana Of M t-herThy RMMarceRdport 91-Lo199 DEEP LAKE r Bany County (73N, R1OWv Seczion 26) Surveyed Septemnber and October 1988 James L Dexter, Jr. Environment Deep Lake is a kettle lake of glacial origin located in west-central Barry County within the Yankees Springs Recreation Area (see map). It lies ab'out 10 miles west of Hastings,A, Michigan. Rollinghil and sandy soils, chifracteri~ze the g,.eography of the area. The watershed is predomntl a mixure of mature oak and red pine forest, with a large amount of oid failow farmland returning to forest. The imediate area surrounding the lake is prmrl scrub-shrubo and wetland underlaid with welb-drained loamy sand soils. One sml unnamedf inlet (top quality coidwater) is at the southern end of the lake and drains throughi Houghiton muck* soils. A sml outlet, Turner Creewk (top quality wr ater), is on the north end; its water flows to the Thornapp le River in the Grand River watershed of Lake Michigan. Deep Lake is 312.4 acres in size and up to 35 fee~t deep. Shoals, comprised priarily of sand and marl, cover 30-40% of the area. Vegetation is sparse except for cattails and rushes. Water quality conditions were last surveyed on August 18, 1986. The water was colorless, and quite clear with a Secchi* disk reading of' 13 feet.. Within the water- column, alklminity ranged from 134 ppm to 145 ppm and pH ranged from 7.4 to 8.4. These indicate the water is hard and well-buffered. Temiperature varied from I 'irt at the surface to 48~F at the bottom, with the thermocine occurring between 10 and 20 feet.. Typically, summer oxygen levelis are sufficient for fish down to a depth of 25 feet. Dissolved oxygenI in the throdline ranged from 5-10 ppm. overall water quality is excellent and presents a very good environment. for a two-story fishery, with a combination of warmwater fish in the upper layer and trout i mid-water. Development around Deep Lk is very liie.The Yankee Springs Recraton Area mitins a campground (120 sites) and a public launch site on the northeast shore. There are a total of five buildines on the lake, but three. of these are sc-heduled to be demolished in 1990, as the state has purchased thsland rectently.o Fishery Resource According to historical records, Deep Lae has been actively managed by the state since. 1934, when largiemouth bass were stocked'. Blue'..l. yellow perch, and more largemouth bass were stocked in varying numbers over the nert 7 years. Rainbow trout fingerlings were stocked for the first time in 11942 and 1943 to try to create a two-story fishery.. In 1944,t gill nets were used to evaluate the ribow trout plants. No riaibows were found, but four large brown trout were captured. Hazmrd (1944) suggested that brown trout had not been stocked for at least 10 years, and that these fish were presumably the result of' natural reproduction (from theO inlet). We have no records, however, of stocking prior to 1934. The fish community in the 19,30s and 1940s consisted mainly of bluegills. largemnouth bass, and yellow perch. Ciscoes were reported by 1 * fishermen, but their presence has never been verified. Rock bass, black crappie, and pumpkinseeds were also available to the angler. The fish community was most recently surveyed on September 29-30 and October 20 -21, 1988. The netting effort entailed an overnight set of two trap nets and six gill nets and a second overnight set of the gill nets. Today's fish community is similar to that of 50 years ago (Table 1). Large bluegills and perch remain the mainstay of the fishery. Other warmwater species are limited by the small amount of shoal habitat Largemouth bass are not very abundant. Northern pike are new to the lake. We netted a 40-inch pike in 1988, and in May 1989, a 43 -inch pike weighing 20 pounds was caught by an angier and entered in the Master Angler Award program. Pike may have entered Deep? Lake either through Turner Creek (which drains into the Thornapple River) or by an unapproved private introduction. It is interesting to note that rainbow trout yearlings, stocked in the spring since 1966 at 43 per acre, formerly provided a very good fishery. In the mid-1980s, however, survival of stocked rainbows may have declined: catches dwindled, and fishing pressure dropped off. The 1988 survey revealed practically the same results as the 1944 survey-no rainbows but five wild brown trout. The decline in the rainbcw fishery could be linked to the presence of northern pike. Just a few large pike could decimate the rainbow stockings. Beginning in 1989, management direction changed to stocking brown trout to supplement their low level of natural reproduction. Growth races of important game fish species are good (Table 2). Yellow perch are growing above state average, and bluegill are growing at state average. Wild brown trout are growing very rapidly. Age composition and survival characteristics of sport fish appear to be normal, considering that relatively few fish were sampled and that the survey nets were not effective for small fish (Table 3). For perch and bluegill, young fish have been regularly recruited to the populations and the longevity of adults is satisfactory. Presence of age-II and age-m brown trout indicates that environmental conditions will be good for the carry-over of stocked trout from year to year. Deep Lake produces larger bluegill and perch than many southern Michigan lakes due to a favorable combination of growth and survival. On a scale of 1 to 7 (Schneider 1990), the quality of the bluegill population ranked 4.8, "good". Bluegills as large as 8.4 inches, perch up to 11.1 inches, and brown trout up to 19.9 inches were taken during the 1988 survey. Fishing on Deep Lake is a very pleasurable experience. It does not receive intense fishing pressure, and the water is clear and inviting. Water quality will be preserved because the state owns almost all the land surrounding the lake. Access is assured through the campground. Bluegifls and yellow perch should continue to provide good fishing. Hopefully fishermen will key in on the brown trout now stocked. With only a few buildings visible from any point on the lake, and the good fishing available, the lake provides a high quality experience. Management Direction This lake will continue to be managed as a two-story fishery. Currently the only special management practiced on Deep Lake is the annual stocking of 1.300 yearling brown trout. As very few lakes in southern Michigan are stocked with browns, we are not sure how good a fishery they will provide at Deep Lake. The possibility exists that a very high quality fishery will develop, as evidenced by the lake's history of large brown trout. Our goals for the next 6 years will be to (1) maintain the bluegill and yellow perch fishery, and (2) develop the brown trout fishery. No problems are expected to develop with goal Number 1; however, goal Number 2 may be difficult to reach. Brown trout are notoriously more difficult to catch than rainbows. We will rely heavily on reports from park personnel to determine if anglers are fishing for browns and their success rate. In addition, we may evaluate the brown trout fishery by tagging fish and soliciting tag returns from anglers. References Hazzard, A. S. 1944. Management check on Deep Lake, Barry County. Michigan Department of Conservation, Fisheries Research Report 970, Ann Arbor. Schneider, J. C. 1990. Classifying bluegill populations from lake survey data. Michigan Department of Natural Resources, Fisheries Technical Report 90-10, Ann Arbor. Report completed: February 16, 1990. Table 1.-Number, weight, and length indices of fish collecaed from Deep Lake with gill and trap nets, September 29-30 and October 20-21, 1988. Percent Weight Percent Length range Average Percent Species Number by number (pounds) by weight (inches)' length legal size2 Bullhead spp. 84 38.9 34.3 36.4 5-12 8.9 92 Bluegill 53 24.5 8.9 93 5.2-8.4 6.4 55 Yellow perch 30 13.9 9.0 9.4 6.6-11.1 9.1 97 Lake chubsucker 15 6.9 3.5 3.7 6-8 7.5 - Pumpinseed 6 2.8 1.6 1.7 9-11 5.5 17 Grass pickerel 6 2.8 1.6 1.7 9-11 10.5 - Brown trout 5 2.3 7.7 8.1 12.8-19.9 15.9 100 Largemouth bass 5 2.3 0.7 0.7 6.3-9.3 8.1 0 Rock bass 3 1.4 0.7 0.7 5-6 5.8 33 Warmouth 3 1.4 0.1 0.1 4 4.5 0 Bowdn 2 0.9 8.9 93 11-29 20.5 - Golden shiner 2 0.9 0.3 0.3 7-8 8.0 - Northern pike 1 0.5 16.2 17.0 - 40.2 100 White sucker 1 0.5 1.5 1.6 - 14.5 - Total 216 100.0 95.5 100.0 0 tNote some fish were measured to 0.1 12.0 to 12.9 inches; etc. inch. others to inch group: e.g.. "5" = 5.0 to 5.9 inches; "2" = -Percent legal size or acceptable size for angling. 3 Table 20"--.-Average total len~gth (inches) at age, and growth relative to the state average., for five species or" fish sampled from Deep Lake with gillan trap nets, September 29-30 and October 20-21, 198. Number of fish aged is given in parentheses. Mean A~re growth Species I El II IV V VI VII VII index' Brown trout - 15.21 19.9---- - (4) -(1) ---- Bluegil 5.4 5.9 7.0 7.8 8.3-- +0.3 - (3) (9) (13") (3) (3)Yellow perch 6.6 8.0 8.7 9.7 11.1 - - - +1.2 Largemouth bass - 7.4 03 - - - - -- - (4) () ---- Northern pike -- - --- 40.2'7 'M.ean growth index is the average deviati~on from the state aver"age length at agye. Table 3.-Estimated age frequency (percecnt) of five species of fish caught from Deewp Lake with gill and tratp nets, September 29-30 and October 2.0-21, 1988. Aee Number Species 1 II1 II IV V VI VII VIMcaught Brown trout - 80 20 - - - - - 5 Blueg1 - 15 40 z327 8 5 - - 53 Yellow Perch 4 11 56 26 3 - - - 30 4 S 0 N Ol 300, 1 inch DEEP LAKE AREA = 32..4 acres BARRY COUNTY T.3N R.IOW SOEC.26 INS71TUTE for FISHE.RIES RESEARCH, 193*I6 E' NCRCACIING BCG SCCONTOUR DEEP LAKE Barry County (T3N, ROW, Section 26) MANAGEMENT PLAN based on Status of the Fishery Resource Report 91-1 James L Dexter, Jr. Management goals based on the 1988 survey are twofold. Goal number one is to maintain the good bluegill and yellow perch populations and fisheries. No active management is proposed to achieve this goal. A possible obstacle to it is that heavy stocking of brown trout (goal number 2) may have a negative effect on panfish. This effect, and overall progress towards goal number 1, will be monitored by conducting another fish survey in fall 1994. Specifically, length-frequencies, growth rates, and catch rates of bluegill and yellow perch will be compared to data obtained in previous surveys. Goal number two is to develop a high-quality brown trout fishery. Steps to achieve this goal include: (a) stocking of yeariing brown trout at the rate of 40 per acre per year from 1989 to 1994; (b) public notification, through press releases, of the stocking change from rainbow trout to brown trout; (c) maintaining contact with park personnel to monitor angler results; and (d) resurveying the fish populations in fall 1994 to evaluate success. Some portion of the stocked brown trout may also be tagged to determine angler utilization via voluntary tag returns. The tagging phase will be implemented if similar projects now underway at other lakes indicate this type of tagging is a suitable evaluation tool. We see few obstacles to the success of brown trout stocking. Water quality is good and trout have grown and survived well in Deep Lake in the past. A serious threat to success would be a buildup of northern pike, either from additional immigration or from the establishment of natural reproduction. Status of trout survival and growth, and of northern pike abundance, will be evaluated in the 1994 fish survey. The epected yield to the fishery at Deep Lake is uncertain because brown trout are hard for angiers to catch and few other small lakes have been intensively managed for brown trout. Optimistically, perhaps 25% of the stocked fingerlings will eventually be harvested by anglers, an average of about 300 per year. Most will be harvested when they reach 10-14 inches in length, but a relatively large number may provide high-quality fishing at lengths of 18-22 inches. Plan completed: February 1991 Approved: David Johnson. District Biologist, March, 1991 Donald Reynolds, Regional Biologist, March, 1991