-- r~t~B ~h:..I?:61 y.~ r~~~; i: _: i r~r it;,,t~ I;i.~;~;-..~-i.; " i~sC-h ~r6L'f F Tr~r~p 5 85-2 FISHERIES DIVISION TECHNICAL REPORT Platte River Harvest Weir and Coho Salmon Egg-Take Report, 1984 I 9 q;zz) oozý= Number 85-2 July 10, 1985 I I I I U I-I _- ____m m - mmLL -b, Michigan Department of Natural Resources * Ii. Ii /1 it 'it I MICHIGAN DEPARTMENT OF NATURAL RESOURCES FISHERIES DIVISION Fisheries Technical Report No. 85-2 July 10, 1985 PLATTE RIVER HARVEST WEIR AND COHO SALMON EGG-TAKE REPORT, 1984 Charles H. Pecor 2 Introduction Since 1966 the Platte River, Benzie County, has been the primary source of brood fish for Michigan's coho salmon stocking program. Eggs are collected each fall at the Platte River State Fish Hatchery, located 4.0 miles east of Honor (Fig. 1). The young coho are raised to the smolt stage (about 5.5 inches long) in 1.5 years and stocked at selected sites throughout Michigan. Prior to 1979, between 265,000 and 1,092,000 (average 607,000) coho smolts were stocked in the Platte River (Table 1)1. This produced sufficient adults for egg-take operations plus a spectacular Lake Michigan sport fishery from Frankfort to Platte Bay in August and September. Since 1979 the annual plant has approximated 1,000,000 smolts. Annual returns to the weirs from the larger plants have ranged from 123,000 to 168,000 adults, or 12.7% to 16.4%. The Platte River has two salmon blocking weirs. The lower weir is located 1.6 miles upstream from the river mouth (Fig. 1). Since 1980 it has been the primary site for harvesting surplus salmon. Steelhead runs are monitored there also. The upper weir, located at the Platte River Hatchery, has facilities for holding adults and collecting eggs. Current in-state and out-of-state commitments require the collection of about 16 million coho eggs annually. Depending on the size of the returning coho, the egg-take requires about 6,500-7,500 adult females (age 1.1).2 To assure that enough females are available for egg take, the Fisheries Division has directed that the first 30,000 salmon reaching the lower weir be passed upstream (allowed to swim through the open weir). An additional 3,000 salmon are passed each week to maintain a sport fishery in the river. However, the above numbers may be modified by the biologist-in-charge as conditions dictate. Other salmon blocked by the lower weir (including surplus coho adults, a moderate run of chinook and, in recent years, a few pink salmon) are collected and harvested. Coho jacks (age 1.0) are small enough to swim upstream through the weir grates. Trout that are collected during harvest operations are counted and released upstream. This includes a moderate run of steelhead plus small runs of brown trout and lake trout. All salmon collected at the upper weir are harvested, including the coho used for egg-take. 'This is a revision from the 400,000 to 600,000 figures cited in last year's report (Pecor and Beyerle 1984). 'An age of 1.1 for an anadromous fish means that one winter was spent in the river prior to smelting and one winter was spent in Lake Michigan after smolting. 3 Lower Weir Operation, 1984 The 1984 salmon run in the lower Platte River was typical. The salmon produced an excellent open -water fishery in the Frankfort - Platte Bay area for over 3 weeks. They ran the river when expected and also in the numbers expected. Salmon that were passed upstream at the lower weir stayed in the river system for a sufficient period of time to allow a good sport fishery before moving up to the hatchery. Consequently, few anglers complained that there were ofno " fish in the river or connecting lakes. The lower harvest weir was in place and ready for operation on September 10. The weir was manned 24 hours per day from September 10 to October 23. Very few salmon appeared at the weir until September 14 when a minor run entered the river. On September 25 and 26, the major run entered the river and moved up to the weir. Harvesting began on September 15 and ended October 23. During the 18 days salmon were actually loaded, 23 semi -trailer loads of salmon were trucked to Tempotech Industries in Hart, Michigan. From September 11 to October 20, a total of 38,577 salmonids (salmon plus trout) were allowed to pass through the open weir (Table 2). The species composition of these fish is assumed to be the same as that of fish actually handled during each week of harvesting. Additional trout were sorted out during harvesting and transferred upstream from the weir. Coho salmon Harvest of coho salmon began September 15 and ended October 23, a period of 38 days. A total of 105,530 adult coho weighing 584,392 pounds were harvested (Table 3). About onehalf of the harvest occurred during the 4 days from September 25 to 28 (Fig. 2). Mean weight of the harvested coho was 5.5 pounds. An estimated 36,572 additional coho were passed upstream for egg-take operations at the upper weir (Table 2). The age composition of the harvested coho was almost exclusively age 1.1. It was estimated that 50 to 75 male coho "jacks" (age 1.0) were harvested but none were included in the weekly biological samples. In addition, about five age 1.2 coho were harvested; one was 36.8 inches long and weighed 16.6 pounds. The average lengths and weights for age 1.1 males and females calculated from weekly biological samples are shown in Table, 4. There was no trend to these averages in 1984 as there 4 fish, respectively. During the next 2 weeks the coho averaged 18% bright, and in the last 2 weeks only 7% bright. Overall, 40% of the coho harvested were categorized as bright fish. During six weekly biological surveys, a total of 862 coho were randomly sampled. Two fish had healed lamprey wounds and 15 fish had fin clips. The fin clips were adipose (AD, 12 fish), left pectoral (LP, 2 fish), and right pectoral (RP, 1 fish). All three clips were assigned to the Ohio Department of Natural Resources for coho plants in Lake Eire. In summary, a total of 142,102 adult coho salmon reached the lower Platte River weir during the fall of 1984, 78,183 (55%) males and 63,919 (45%) females (Table 4). The total adult run was 14.9% of the 1983 plant of 953,049 age 1.0 smolts (Table 5). Chinook salmon The harvest of chinook salmon coincided with that of coho salmon. However, chinook were in the harvest on only 14 of the 18 days salmon were actually loaded. As usual, the peak chinook harvests occurred between October 1 and 17 after the peak coho harvest (Table 6). A total of 4,358 chinook weighing 64,328 pounds were harvested (Table 6). Average weight was 14.8 pounds. It was estimated that an additional 1,566 chinook were passed upstream at the lower weir (Table 2). Biological samples of 418 chinook were taken, including 317 scale samples. All scale samples (chinook, steelhead, and brown trout) were read by the District 6 fisheries crew at the Harrietta warehouse. Analysis of the chinook scale samples showed that 5% were age 0.1, 14.8% were age 0.2, and 80.1% were age 0.3 (Table 7). Based on these numbers, the total chinook run (both harvested and passed) in the Platte River consisted of 299 age-0.1, 878 age0.2, and 4,747 age-0.3 fish. The age composition of the Platte River chinook run was substantially different than that for the Little Manistee River run in 1983, in that there were fewer age-0.1 and -0.2 and more age-0.3 fish. In 1983 the Little Manistee River chinook were 22.5% age-0.1, 44.8% age-0.2, and 32.7% age-0.3 fish (Hay 1984). This could imply that there will be few chinook running the Platte River the next 2 years, or that the self-sustaining population in the Platte River behaves differently than the stocked population in the Little Manistee River. The average lengths and weights for Platte River chinook, stratified by sex and age, are presented in Table 7. Only one chinook with a healed lamprey scar was recorded during the biological samples and no fin clips were observed. The total of 5,924 chinook reaching the lower weir in 1984 was the second largest run since full-scale operations of the weir began in 1980 (Table 8). Males and females comprised 53% and 47% of the run, respectively. All chinook were either strays from other plants, escapees from the Platte River Hatchery, or the result of natural reproduction since chinook are not planted in the Platte River. 5 Pink salmon Pink salmon were not expected this year and did not show up in the harvest or around the weir. Pink salmon normally run only during odd number years. Steelhead trout The major portion of the steelhead run occurred after the peak of the coho salmon harvest, from October 7 to the end of harvest operations on October 23 (Table 9). This pattern has been consistent since 1980, although the dates have varied from year to year. Many steelhead run the river after the weirs are removed; therefore, the weir counts are only a rough index of the magnitude of the steelhead run. A total of 1,292 steelhead were actually counted and transferred (Table 9). This was the second largest tally of steelhead in the Platte River since full-scale operations began in 1980 but it was the first year to show a decline from the previous year. The number of steelhead counted and transferred in 1983, 1982, 1981, and 1980 were 1,545, 1,276, 682, and 124, respectively. In addition, an estimated 401 steelhead passed through the weir with the coho salmon, making a total run of 1,693 steelhead in 1984 (Table 9). Biological information was collected for 274 steelhead. A total of 10 age groups were recorded (Table 10). The most common age groups, listed in order of decreasing frequency, were 2.1, 1.1, 1.0, 2.0, 2.2, and 1.2. Together, these six age groups accounted for 97.6% of the sample. Many (42%) of the steelhead had spent two summers in the lake (Table 11). The amount of time the steelhead spent in the river prior to smolting was fairly evenly split between one and two summers (Table 10). Steelhead in age groups 1._ and age groups 2. accounted for 45 and 54% of the run, respectively. Age groups 3. and 4. combined, accounted for only 1% of the run. The size of the returning steelhead was more dependent upon years spent in Lake Michigan than on age at smolting or years in the river (Fig. 3). Fish which had spent equal amounts of time in Lake Michigan were of about equal size, irregardless of the amount of time spent in the river. For example, all steelhead which had spent one winter in Lake Michigan (age _.1) were about 24 inches long and weighed about 6 pounds even though they had spent 1, 2, or 3 winters in the river before smolting (Table 11). Overall, the steelhead in the 1984 run had a mean length of 22.8 inches and a mean weight of 5.49 pounds and consisted of 48.9% males and 51.1% females. No lamprey scars or fin clips were observed on any steelhead. Brown trout and lake trout Brown trout and lake trout are only minor components of the salmonid run in the Platte River (Table 9). A total of 74 brown trout were counted and transferred upstream in 1984, as 6 compared to 58 in 1983, 38 in 1982, 78 in 1981, and 7 in 1980. A total of 69 lake trout were counted and transferred upstream in 1984 as compared to 7 in 1983 and 38 in 1982. Lake trout were not observed in the runs during 1980 and 1981. During 1984, it was estimated that an additional 22 brown trout and 14 lake trout were passed upstream with coho salmon. This gives total runs during 1984 of 96 brown trout and 83 lake trout. For both species, the peak runs occurred during the week beginning October 7, after the peak harvest of coho was over. Biological information was obtained from 16 brown trout which died after being passed upstream. Five age groups were identified - 1.0, 1.1, 2.1, 3.0, and 3.1 - but most were in age groups 1.1 (6 fish) and 2.1 (7 fish). Lengths ranged from 19.3 to 24.5 inches (average, 22.6) and weights from 3.42 to 7.61 pounds (average, 6.04). The sex ratio was 81% male to 19% female. All but one of the handled lake trout were fin clipped. Observed fin clips were both ventrals (BV), left ventral-adipose (LV-AD), and right pectoral-adipose (RP-AD). All three clips (1980, BV; 1979, LV-AD; 1976, RP-AD) were assigned to yearling lake trout planted offshore on either Good Harbor Bay Reef (located about 18.6 miles north of the Platte River) or South Fox Island Shoal (located about 43.5 miles north of the Platte River). Fifty-five percent of the lake trout had the BV clip, 42% had the LV-AD clip, and 3% had the RP-AD clip. The lake trout with the BV clip were the smallest fish, but a length and weight sample was not taken. Two lake trout with the LV-AD clip had a mean length of 27.8 inches and a mean weight of 7.94 pounds, and one lake trout with the RP-AD clip was 31.5 inches long and weighed 11.5 pounds. Upper Weir Operation, 1984 The operation at the upper Platte River weir is primarily for egg-taking and does not have the capability of harvesting large numbers of salmon efficiently. The facility consists of a weir, fish passage way, fish ladder, maturation ponds, and egg-take building. The weir blocks the upstream migration of salmonids and directs them up the fish ladder into the maturation ponds. Two to three thousand fish can be held in each of the six maturation ponds. The salmon are held in these ponds for up to 3 weeks while the eggs mature or "ripen", then the eggs are stripped and fertilized. The weir stop-logs were in place by August 31 and the fish holding-egg taking facility was fully operational by September 4. Coho salmon The first coho salmon (one adult and 7-9 jacks) reached the maturation ponds the day after the weir logs were installed (as usual). Larger numbers of coho started showing up at the weir by September 15. No main run of coho occurred, instead, the salmon held back in the 7 river system and slowly migrated into the maturation ponds. All six maturation ponds were full by October 12 and additional fish were held in the river below the weir. The fish in the maturation ponds were checked weekly for egg condition (green and ripe) starting October 9 and ending November 14. Egg-taking operations started when the proportion of ripe females was 50% or above. The percentage of ripe females on October 9, 16, 22, 30, and November 14 were 47.4, 74.3, 58.2, 93.1, and 97.9%, respectively. A total of 15,256,700 eggs were collected and fertilized on 14 working days between October 15 and November 2. Of these eggs 7,076,100 (46.4%) were for in-state rearing and 8,180,500 (53.6%) were for out -of -state commitments (i.e., Indiana, 0.5 million; Wisconsin, 1.2 million; Illinois, 2.3 million; Pennsylvania, 2.8 million; and Ohio, 1.3 million). The 1984 egg-take was carried out as a routine operation, however, we had some problems with egg quality. During the first week of egg -take we experienced a relatively high percentage of poor quality and/or overripe "buckshot" eggs. We then switched to fresh -run fish, and although the percentage of overripe eggs decreased the percentage of green eggs increased. We switched back to the earlier run fish to finish the egg -take but again experienced a high percent age of overripe eggs. The poor egg quality may have been due in part to high water temperatures in the Platte River. Water temperatures at the lower weir were above 16 C (61 F) and as high as 19 C (66 F) until September 29, the period when most of the salmon were passed upstream. There were also periods of high water temperatures (15 C) at the upper weir while the fish were in the maturation ponds. Washington State biologists feel that if salmon are exposed to water temperatures above 14.5 C (58 F) during this period, their egg quality will be reduced (Appleby, personal communication). The eye -up rate of coho salmon eggs incubated at the Platte River Hatchery also reflected the poor quality of the 1984 eggs. The average percentage eye -up for the 7 egg -take days was 50.4%, with a daily range from 46.8% to 57.7%. The eye-up of the coho eggs taken for Ohio on the last day of egg-take was only 35%. Coho eye-up percentages in recent years were 63.0% in 1979, 82.2% in 1980, 71.4% in 1981, 55.9% in 1982, and 77.1% in 1983. A total of 7,711 female coho salmon were stripped (Table 12) to collect 15.26 million eggs, an average of 1,979 eggs per female. A check of the fecundity of 25 individual females at the end of the run showed an average of 2,290 eggs per female with a range of 1,075 to 3,703. The difference between 1,979 and 2,290 represents the eggs that were retalned by stripped 8 weir. I suspect that a very high loss can be attributed to fishing mortality. During 1983, 8,732 (24.5%) did not swim to the upper weir. The adult run at the upper weir consisted of 49.1% males and 50.9% females. Males averaged 25.0 inches in length and 4.93 pounds in weight, and females averaged 24.3 inches and 5.03 pounds. Overall, the adult coho averaged 24.6 inches and 4.98 pounds. They were slightly shorter (0.2 inches) but much lighter (0.48 pounds) than adult coho harvested at the lower weir. Almost 98% of the adult coho handled at the upper weir were used in the egg-taking operation and only about 460 fish were harvested as surplus. In all, 116,157 pounds of coho salmon were harvested at the upper weir. A total of 1,663 jack coho salmon (100% males) were harvested at the upper weir. Assuming that the number of jack coho harvested at the upper weir was also 67% of the total jacks passed at the lower weir, the total 1984 jack run was estimated to be 2,482 fish. This represents 0.2% of the total coho smolt plant in 1984 and 1.7% of the total estimated run of 144,584 coho in the Platte River during 1984. Mean length and weight of jacks calculated from periodic biological samples were 15.8 inches (standard error ~0.13 inches) and 1.50 pounds (standard error ~0.037 pounds), respectively. The weighted mean weight of jacks calculated from harvest data was 1.41 pounds (Table 13). In 1983, the jacks averaged 16.4 inches in length and 1.61 pounds in weight. Two jacks out of 104 (6.3% of the jack run) taken for biological samples had fin clips. One had an adipose (AD) clip and the other had a left pectoral (LP) clip. The AD jack could have come from 1984 plantings (1982 brood year) in Michigan waters of Lake Superior, or it could have escaped from the Platte River Hatchery during rearing. The LP jack could have come from Illinois waters of Lake Michigan or from Ohio waters of Lake Erie. Chinook salmon Most (60%) of the chinook at the upper weir were harvested on two dates, October 31 and November 2 (Table 13). The average weight of chinook (adults and jacks combined) was 11.68 pounds. The total harvest of 215 fish was only 13.7% of the estimated number of chinook passed at the lower weir. Again fishing mortality is suspected as the major cause of this loss. Summary The 1984 run of coho salmon in the Platte River consisted of 142,102 adults (55% male and 45% female). This is a return of 14.9% of the smolts planted in 1983. Mean lengths and weights at the lower weir were 25.1 inches and 5.49 pounds for adult males and 24.4 inches and 5.51 pounds for adult females. Mean lengths and weights at the upper weir were 25.0 inches 9 and 4.93 pounds for adult males, 24.4 inches and 5.03 pounds for adult females, and 15.8 inches and 1.41 pounds for jack coho salmon. A grand total of 131,692 coho adults and jacks weighing 700,551 pounds were harvested. A total of 105,530 adults weighing 584,393 pounds were harvested at the lower weir and 26,162 adults and jacks weighing 116,158 pounds were harvested at the upper weir. The upper weir harvest included 7,711 stripped females weighing 31,336 pounds from which the 1984 consignment of 15,256,700 eggs were taken. The quality of the 1984 eggs was poor as reflected in an average eye -up of only 50.4% for the eggs incubated at the Platte River Hatchery. The 1984 run of 5,924 chinook (53% males and 47% females) was the second largest recorded at the lower Platte River weir. Ultimately, 4,573 of these chinook (77.2%, 66,843 pounds) were harvested - 4,358 at the lower weir and 215 at the upper weir. The age composition of the chinook run was 5% age-0.1 jacks, 14.8% age-0.2 adults, and 80.1% age-0.3 adults. The mean lengths and weights for age groups 0.1, 0.2, and 0.3 were 22.3 inches and 4.4 pounds, 32.1 inches and 11.35 pounds, and 34.2 inches and 16.23 pounds, respectively. The 1984 fall steelhead run of 1,693 fish (48.9% male and 51.1% female) was the second largest run recorded at the lower weir in recent years. Ten different age groups were identified but fish which had spent two summers in Lake Michigan (age groups 1.1 and 2.1) were the most numerous (41.3%). Overall, the steelhead averaged 22.8 inches long and weighed 5.49 pounds. Other salmonids passed upstream at the lower weir included 96 brown trout and 83 lake trout. All lake trout except one were fin clipped and had originated from plants made at Good Harbor Bay Reef or South Fox Island Shoal. 10 LAKE MICHIGAN PLATTE BAY / BENZIE CO. LINE /EST WEIR TE PLATTE RIVER HATCHERY ýKE AND UPPER HARVEST WEIR HONOR BEULAH MILES 0 1 2 Figure 1. Location of the Platte River Hatchery and the upper and lower harvest weirs. 11 30 n Passed 25 Harvested Oz Z un 20 D 0 I-- I z 0 0 x40 C) 0 5 9-15 16-22 23-30 1-6 7-13 '14-20 21-27 SEPT OCT Figure 2. Periodicity of coho salmon harvested and passed upstream at the lower Platte River weir, fall 1984. 12 35r Length Weight I ~2Standard Errors 30ký LU o25 z S20 z LU1 Z45 LU 18 16 CL).44 12 40 87 LU) 8z 4 2 0 SF / /S 5 0 SI I I~ I I I I I 1.0 2.0 4.0 1.1 2.1 3. 1 AGE 1.2 2.2 1.3 2.3 Figure 3. Mean total length and round weight of steelhead, by age, at the lower Platte River weir, fall 1984. 13 Table 1. Number of anadromous salmonids planted in the Platte River, 1966-84. Atlantic Year Coho Chinook Steelhead salmon 1966 1967 1968 1969 1970 1971 1972 1973 1974 1975 1976 1977 1978 1979 1980 1981 1982 1983 1984 Total 265,000 503,000 309,000 1,092,069 777,640 390,381 406,330 918,135 804,131 800,202 500,903 606,814 516,202 973,032 1,028,038 944,205 1,000,010 953,499 989,192 13,777,783 53,500 40,630 94,130 206,924 100,386 87,600 394,910 7,308 7,308 14 Table 2. Total number of salmonids (salmon plus trout) and estimated number of coho and chinook salmon passed upstream at the lower Platte River weir, fall 1984. Coho Chinook Percent Estimated Percent Estimated Salmonids in number in number Date passed harvest' passed harvest' passed 9/11 9 9/12 207 9/13 1,125 9/14 4,216 9/15 6,616 Weekly total 12,173 98.59 12,001 1.01 122 9/16 3,682 9/18 904 9/19 96 9/21 137 9/22 1,187 Weekly total 6,006 91.10 5,472 8.41 505 9/23 1,178 9/25 100 9/26 5,000 9/27 5,500 Weekly total 11,778 98.80 11,636 0.97 114 10/03 1,000 10/04 1,000 10/05 500 10/06 500 Weekly total 3,000 96.00 2,880 3.17 95 15 Table 2. Continued: Coho Chinook Percent Estimated Percent Estimated Salmonids in number in number Date passed harvest' passed harvest' passed 10/07 500 10/08 500 10/09 500 10/10 500 10/11 500 10/12 500 Weekly total 3,000 85.49 2,565 10.76 323 10/17 120 10/18 1,000 10/19 500 10/20 1,000 Weekly total 2,620 77.03 2,018 15.55 407 Annual total 38,577 94.80 36,572 4.06 1,566 'Percentage of the harvested or handled salmonids which were either coho or chinook. 16 Table 3. Summary of adult coho salmon harvested at the lower Platte River weir, fall 1984. Coho harvested Total Cumulative weight Date Live Mortalities total (pounds) 9/15 4,900 0 4,900 27,930 Weekly total 4,900 0 27,930 9/16 1,680 0 6,580 9,577 9/20 910 15 7,505 5,269 9/21 6,440 0 13,945 34,132 9/22 1,470 0 15,415 7,791 Weekly total 10,500 15 56,769 9/25 16,240 0 31,655 87,697 9/26 22,540 0 54,195 121,716 9/27 9,940 0 64,135 53,675 9/28 2,105 35 66,275 12,284 Weekly total 50,825 35 275,372 10/01 6,598 0 72,873 37,872 10/02 5,870 50 78,793 34,297 10/03 5,220 0 84,013 30,276 10/04 6,525 0 90,538 37,844 Weekly total 24,213 50 140,289 10/07 2,755 120 93,413 16,387 10/10 4,704 298 98,415 28,512 10/12 2,320 0 100,735 12,760 Weekly total 9,779 418 57,659 10/17 3,000 21 103,756 16,616 Weekly total 3,000 21 16,616 10/23 1,740 34 105,530 9,757 Weekly total 1,740 34 9,757 Annual total 104,957 573 105,530 584,392 17 Table 4. Estimated number of adult male and female coho salmon returning to the lower Platte River weir and their mean length and weight (~ standard error of mean) based on weekly biological samples, fall 1984. Number of coho Mean Week Length Weight beginning Harvested Passed Total (inches) (pounds) Age 1.1 male 9/09 1,725 4,468 6,193 25.1~0.26 5.69~0.18 9/16 5,443 2,832 8,275 24.9~0.14 5.22~0.09 9/23 36,205 8,280 44,485 25.3 ~0.14 5.40~0.09 9/30 10,319 1,225 11,544 25.3~0.18 5.93 +~0.14 10/07 3,920 986 4,906 24.3 ~0.17 5.42 ~0.12 10/14 1,233 823 2,056 - - 10/21 724 0 724 25.7~0.21 5.58~0.18 Total weighted mean' 59,569 18,614 78,183 25.1 5.49 Age 1.1 female 9/09 3,175 7,583 10,708 24.6~0.14 5.64~0.12 9/16 5,072 2,640 7,712 24.4~0.18 5.36~0.14 9/23 14,655 3,356 18,011 24.5 ~0.11 5.40~0.09 9/30 13,944 1,655 15,599 24.3 +~0.13 5.62 +~0.09 10/07 6,277 1,579 7,856 24.1~0.10 5.49~0.08 10/14 1,788 1,195 2,983 - - 10/21 1,050 0 1,050 24.6 ~0.12 5.51~ 0.10 Annual weighted mean' 45,961 17,958 63,919 24.4 5.51 Sexes combined 105,530 36,572 142,102 24.8 5.49 'For computing weighted means, means for week week of October 14. of October 7 were extrapolated to 18 Table 5. Summary of adult coho (age 1.1) 1979-84. runs at the lower Platte River weir, Estimated Plant in Mean Mean number Number Total previous Percent length weight Year passed harvested run year return (inches) (pounds) 1979 36,404 0 36,404 516,200 7.1 23.1 4.36 1980 76,4801 46,633 123,113 973,032 12.7 26.9 7.61 1981 38,874 129,175 168,049 1,028,038 16.3 27.0 6.83 1982 38,951 90,412 129,363 944,205 13.7 25.8 6.15 1983 35,600 120,758 156,358 1,000,010 15.6 26.6 6.86 1984 36,572 105,530 142,102 953,449 14.9 24.8 5.49 'Fish not counted; estimated from harvest at upper weir. 19 Table 6. Summary of all chinook harvested at the lower Platte River weir, fall 1984. Chinook harvested Total Cumulative weight Date Live Mortalities total (pounds) 9/15 50 0 50 796 Weekly total 50 0 796 9/16 612 1 663 9,747 9/20 45 0 708 699 9/22 313 0 1,021 4,727 Weekly total 970 1 15,173 9/26 455 0 1,476 7,143 9/28 44 0 1,520 690 Weekly total 499 0 7,833 10/01 91 0 1,611 1,429 10/02 50 0 1,661 721 10/04 659 0 2,320 9,490 Weekly total 800 0 11,640 10/07 630 9 2,959 8,521 10/10 429 12 3,400 6,572 10/12 204 0 3,604 2,939 Weekly total 1,263 21 18,032 10/17 570 40 4,214 8,783 Weekly total 570 40 8,783 10/23 133 11 4,358 2,072 Weekly total 133 11 2,072 Annual total 4,285 73 4,358 64,329 20 Table 7. Age composition and mean lengths and weights (~ standard error of mean) of 317 chinook salmon scale sampled at the lower Platte River weir, fall 1984. Percent Age of Mean Mean and total length weight sex Number sample (inches) (pounds) Age 0.1 Male Female Both Age 0.2 Male Female Both Age 0.3 Male Female Both 16 0 16 5.0 0 5.0 22.3 ~0.336 22.3 ~0.336 4.41 ~0.17 4.41 0.17 26 21 47 126 128 254 8.2 6.6 14.8 39.8 40.4 80.2 32.0 0.308 32.2 0.272 32.1~0.207 36.8 ~0.218 35.6~0.171 36.2 0.143 11.09~0.47 11.68 ~0.48 11.35 ~0.34 16.51~0.33 15.98 ~0.26 16.23 ~0.21 21 Table 8. Summary of chinook runs at the lower Platte River weir, 1979-84. Estimated Mean Mean number Number Total length weight Year passed harvested run (inches) (pounds) 1979 4,159 543 4,702 0.0 0.00 1980 2,7361 1,699 4,435 32.8 14.51 1981 1,391 2,172 3,563 34.7 15.56 1982 1,393 1,606 2,999 34.4 14.00 1983 1,275 4,839 6,114 33.6 14.73 1984 1,566 4,358 5,924 34.8 14.75 'Fish not counted; estimated from harvest at upper weir. 22 Table 9. Number of trout released upstream at the lower Platte River weir, fall 1984.1 Steelhead Brown trout Lake trout Date Handled Passed Handled Passed Handled Passed 9/15 18 2 Weekly total 18 44 2 5 0 0 9/17 5 1 1 9/20 22 1 9/21 26 Weekly total 53 28 1 1 2 1 9/25 60 3 9/26 41 1 9/27. 13 2 Weekly total 114 26 6 1 0 0 10/01 61 9 1 10/02 31 4 10/03 30 5 6 10/04 48 7 10 Weekly total 170 20 25 3 17 2 10/07 102 6 20 10/10 171 13 12 Weekly total 384 97 30 7 33 8 10/17 279 8 4 Weekly total 279 186 8 5 4 3 10/23 274 2 13 Weekly total 274 0 2 0 13 0 Annual total 1,292 401 74 22 69 14 23 Table 10. Age composition and mean lengths and weights (~ 1 standard error of mean) of 276 steelhead trout at the lower Platte River weir, fall 1984. Age Mean Mean and length weight sex Number Percent (inches) (pounds) Age 1.0 Male Female Both Age 2.0 Male Female Both Age 4.0 Male Female Both Age 1.1 Male Female Both Age 2.1 Male Female Both Age 3.1 Male Female Both Age 1.2 Male Female Both 27 14 41 16.0 ~0.23 15.9~0.46 16.0~0.21 1.81~0.08 1.85 ~ 0.20 1.83 ~0.08 14.9 29 12 41 16.7 ~0.28 17.4~0.56 16.9~ 0.26 2.12 ~ 0.10 2.38 ~0.21 2.18 ~0.09 14.9 1 0 1 18.7 18.7 3.09 3.09 0.4 18 28 46 23.6 ~0.62 23.9 ~0.36 23.8 ~0.32 5.53 ~0.39 5.86 ~0.25 5.73 ~0.22 16.7 22 46 68 24.2 ~0.55 24.2 ~ 0.27 24.1 ~0.25 6.06 ~ 0.33 6.08 ~0.18 6.06 ~ 0.16 24.6 1 1 2 23.8 25.0 24.4~0.57 5.29 6.39 5.84~0.55 0.7 14 21 35 28.3 ~0.30 27.5 ~0.36 27.8 ~0.25 8.62 ~0.35 8.38 ~ 0.29 8.49 ~ 0.22 12.7 24 Table 10. Continued: Age Mean Mean and length weight sex Number Percent (inches) (pounds) Age 2.2 Male 20 27.3 ~0.50 7.98 ~0.41 Female 18 28.0 ~0.39 8.69 ~0.34 Both 38 13.8 27.6~0.32 8.31~0.27 Age 1.3 Male 1 29.9 10.14 Female 1 29.1 11.24 Both 2 0.7 29.5 ~0.39 10.58 ~0.55 Age 2.3 Male 2 33.0 ~1.67 12.57 ~1.76 Female 0 - Both 2 0.7 33.0 1.67 12.57 ~1.76 Total Male 135 48.9 - - Female 141 51.1 - - Both 276 100.0 22.8 ~0.29 5.49~0.17 25 Table 11. Age composition and mean length and weight ( ~2 standard errors), summarized by summers of growth in Lake Michigan, for steelhead trout sampled at the lower Platte River weir, fall 1984. Summers Percent Mean Mean in of length weight Age lake sample (inches) (pounds) -.0 1 30.1 16.5~0.4 2.03 ~0.13.1 2 42.0 24.0~0.4 5.93 ~0.24.2 3 26.4 27.7~0.4 8.40~0.35.3 4 1.4 31.3~2.4 11.57~1.90 All 22.8 5.49 26 Table 12. Number of coho salmon harvested at the upper Platte River weir, fall 1984. Females Date Jacks Males Round Stripped Mortalities 10/16 365 1,339 1,P246 1,150 450 10/17 86 775 305 500 10/18 124 13,125 295 600 70 10/19 95 840 472 479 10/20 43 900 440 560 Weekly total 713 4,979 2,758 3,289 520 10/22 40 810 525 500 10/23 122 700 125 450 260 10/24 191 11,020 120 650 10/25 112 400 31 275 10/26 199 840 23 590 Weekly total 664, 3,770 824 2,465 260 10/31 249 1,890 112 11,332 250 11/02 27 630 170 625 150 Weekly total 276 2,520 282 1,957 400 11/14 10 161 296 0 18 Weekly total 10 161 296 0 18 Annual total 13,663 11,0430 4,160 7,711 1,198 27 Table 13. Weight (pounds) of coho salmon harvested at the upper Platte River weir, fall 1984. Females Date Jacks Males Round Stripped Mortalities 10/16 432 6,294 51,855 43,601 2,114 10/17 101 3,642 1,0433 2,000 353 10/18 146 5,289 11,387 2,v401 10/19 112 33,948 2,P218 1,916 10/20 51 49,231 23,068 2,V240. Weekly total 842 23.,404 121,961 13,158 2,0467 10/22 40 4,921.3' 2,729 23,099 10/23 194 3,640 650 1,889 11,351 10/24 306 5,0304 623 2,1729 10/25 178 29,079 161 19,155 10/26 317 41,537 117 2,0478 Weekly total 1,v035 193,773 4,280 10,350 1,351 10/31 375 9,26 560 51,329 1,25 11/02 42 31,086 851 21,500 750 Weekly total 417 12,348 1,411 7,829 23,000 11/14 13 853 1,570 0 95 Weekly total 13 853 1,570 0 95 Annual total 2,307 561,378 20,222 ý31,337 5,v913 Mean weight 1.41 4.94 4.87 4.06 4.94 28 Table 14. Number and weight (pounds) of chinook salmon (adults and jacks combined) harvested at the upper Platte River weir, fall 1984. Males Females Mortality Total Date Number Weight Number Weight Number Weight Number Weight 10/16 5 67 4 47 0 0 9 114 10/18 2 25 0 0 0 0 2 25 10/19 6 54 1 15 0 0 7 69 10/20 4 21 1 13 0 0 5 34 Weekly total 17 167 6 75 0 0 23 242 10/22 6 63 0 0 0 0 6 63 10/23 5 33 0 0 0 0 5 33 10/25 1 11 0 0 0 0 1 11 Weekly total 12 107 0 0 0 0 12 107 10/31 30 300 8 102 36 410 74 812 11/02 56 658 17 240 0 0 73 898 Weekly total 86 958 25 342 36 410 147 1,710 11/14 13 179 19 263 1 14 33 456 Weekly total. 13 179 19 263 1 14 33 456 Annual total 128 1,411 50 680 37 424 215 29,515 Mean weight 11.8 13.6 11.5 11.7 29 Literature Cited Hay, R. L. 1984. Little Manistee River harvest weir and chinook salmon egg-take report, 1983. Michigan Department of Natural Resources, Fisheries Technical Report 84-10, Ann Arbor, Michigan, USA. Pecor, C. H., and G. B. Beyerle. 1984. Platte River harvest weir and coho salmon egg-take report, 1983. Michigan Department of Natural Resources, Fisheries Technical Report 84-8, Ann Arbor, Michigan, USA. Report approved by W. C. Latta Typed by G. M. Zurek .11 I! * Hf * $1 I) 11 4. if