c 55. W. UMFS c\RC-l>U4 
 
 NOAATR NMFSCIRC-364 
 
 A UNITED STATES 
 DEPARTMENT OF 
 COMMERCE 
 PUBLICATION 
 
 *** T °'C<fc. 
 
 
 *r. «^ 
 
 NOAA Technical Report NMFS CIRC-364 
 
 U.S. DEPARTMENT OF COMMERCE 
 
 National Oceanic and Atmospheric Administration 
 
 National Marine Fisheries Service 
 
 History and Development of 
 Surf Clam Harvesting Gear 
 
 PHILLIPS. PARKER 
 
 SEATTLE, WA. 
 October 1971 
 
NOAA TECHNICAL REPORTS 
 
 National Marine Fisheries Service, Circulars 
 
 The major responsibilities of the National Marine Fisheries Service (NMFS) are to monitor and assess the 
 abundance and geographic distribution of fishery resources, to understand and predict fluctuations in the quan- 
 tity and distribution of these resources, and to establish levels for optimum use of the resources. NMFS is also 
 charged with the development and implementation of policies for managing national fishing grounds, develop- 
 ment and enforcement of domestic fisheries regulations, surveillance of foreign fishing off United States coastal 
 waters, and the development and enforcement of international fishery agreements and policies. NMFS also 
 assists the fishing industry through marketing service and economic analysis programs, and mortgage insurance 
 and vessel construction subsidies. It collects, analyses, and publishes statistics on various phases of the industry. 
 
 The NOAA Technical Report NMFS CIRC series continues a series that has been in existence since 1941. The 
 Circulars are technical publications of general interest intended to aid conservation and management. Publica- 
 tions that review in considerable detail and at a high technical level certain broad areas of research appear in 
 this series. Technical papers originating in economics studies and from management investigations appear in 
 the Circular series. 
 
 NOAA Technical Reports NMFS CIRC are available free in limited numbers to governmental agencies, both 
 Federal and State. They are also available in exchange for other scientific and technical publications in the ma- 
 rine sciences. Individual copies may be obtained (unless otherwise noted) from NOAA Publications Section, Rock- 
 ville, Md. 20852. Recent Circulars are: 
 
 315. Synopsis of biological data on the chum salmon, 
 Oncorhynchus keta (Walbaum) 1792. By Rich- 
 ard G. Bakkala. March 1970, iii + 89 pp., 15 
 figs., 51 tables. 
 
 319. Bureau of Commercial Fisheries Great Lakes 
 Fishery Laboratory, Ann Arbor, Michigan. By 
 Bureau of Commercial Fisheries. March 1970, 
 8 pp., 7 figs. 
 
 330. EASTROPAC Atlas: Vols. 4, 2. Catalog No. 
 
 1 49.4:330/ (vol.) 11 vols. ($4.75 each). Avail- 
 able from the Superintendent of Documents, 
 Washington, D.C. 20402. 
 
 331. Guidelines for the processing of hot-smoked chub. 
 By H. L. Seagran, J. T. Graikoski, and J. A. 
 Emerson. January 1970, iv + 23 pp., 8 figs., 
 
 2 tables. 
 
 332. Pacific hake. ( 12 articles by 20 authors. ) 
 1970, iii + 152 pp., 72 figs., 47 tables. 
 
 March 
 
 333. Recommended practices for vessel sanitation and 
 fish handling. By Edgar W. Bowman and Alfred 
 Larsen. March 1970, iv + 27 pp., 6 figs. 
 
 335. Progress report of the Bureau of Commercial 
 Fisheries Center for Estuarine and Menhaden 
 Research, Pesticide Field Station, Gulf Breeze, 
 Fla., fiscal year 1969. By the Laboratory staff. 
 August 1970, iii + 33 pp., 29 figs., 12 tables. 
 
 336. The northern fur seal. By Ralph C. Baker, Ford 
 Wilke, and C. Howard Baltzo. April 1970, iii + 
 19 pp., 13 figs. 
 
 337. Program of Division of Economic Research, 
 Bureau of Commerecial Fisheries, fiscal year 
 
 1969. By Division of Economic Research. April 
 
 1970, iii + 29 pp., 12 figs., 7 tables. 
 
 338. Bureau of Commercial Fisheries Biological Lab- 
 oratory, Auke Bay, Alaska. By Bureau of Com- 
 mercial Fisheries. June 1970, 8 pp., 6 figs. 
 
 339. Salmon research at Ice Harbor Dam. By Wesley 
 J. Ebel. April 1970, 6 pp., 4 figs. 
 
 340. Bureau of Commercial Fisheries Technological 
 Laboratory, Gloucester, Massachusetts. By Bu- 
 reau of Commercial Fisheries. June 1970, 8 pp., 
 8 figs. 
 
 341. Report of the Bureau of Commercial Fisheries 
 Biological Laboratory, Beaufort, N.C., for the 
 fiscal year ending June 30, 1968. By the Lab- 
 oratory staff. August 1970, iii + 24 pp., 11 figs., 
 16 tables. 
 
 342. Report of the Bureau of Commercial Fisheries 
 Biological Laboratory, St. Petersburg Beach, 
 Florida, fiscal year 1969. By the Laboratory staff. 
 August 1970, iii + 22 pp., 20 figs., 8 tables. 
 
 343. Report of the Bureau of Commercial Fisheries 
 Biological Laboratory, Galveston, Texas, fiscal 
 year 1969. By the Laboratory staff. August 
 1970, iii + 39 pp., 28 figs., 9 tables. 
 
 344. Bureau of Commercial Fisheries Tropical Atlan- 
 tic Biological Laboratory progress in research 
 1965-69, Miami, Florida. By Ann Weeks. Oc- 
 tober 1970, iv + 65 pp., 53 figs. 
 
 346. Sportsman's guide to handling, smoking, and pre- 
 serving Great Lakes coho salmon. By Shearon 
 Dudley, J. T. Graikoski, H. L. Seagran, and Paul 
 M. Earl. September 1970, iii + 28 pp., 15 figs. 
 
 347. Synopsis of biological data on Pacific ocean perch, 
 Sebastodes alutus. By Richard L. Major and 
 Herbert H. Shippen. December 1970, iii + 38 
 pp., 31 figs., 11 tables. 
 
 Continued on inside back cover. 
 
A1M0SP- 
 
 '^ei\n 
 
 U.S. DEPARTMENT OF COMMERCE 
 
 Maurice H. Stans, Secretary 
 
 NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION 
 Robert M. White, Administrator 
 
 NATIONAL MARINE FISHERIES SERVICE 
 Philip M. Roedel, Director 
 
 NOAA Technical Report NMFS CIRC-364 
 
 History and Development of 
 Surf Clam Harvesting Gear 
 
 PHILLIPS. PARKER 
 
 c 
 O 
 
 5 
 O 
 
 SEATTLE, WA. 
 October 1971 
 
 For sale by the Superintendent of Documents, U.S. Government Printing Office 
 Washington, D.C., 20402 - Price 30 cents Stock number 0320-0035 
 
Clam boats dredging for clams with wet (hydraulic) dredges along the east coast of the United States. 
 
CONTENTS 
 
 Page 
 
 Introduction 1 
 
 Manual collecting methods 2 
 
 Hand collecting 2 
 
 Rakes 2 
 
 Tongs 2 
 
 Power collecting methods 2 
 
 Scraper-type dredges 2 
 
 Hydraulic dredges 4 
 
 Experimental gear 7 
 
 Vessels 12 
 
 Summary 12 
 
 Literature cited 13 
 
 FIGURES 
 
 Page 
 
 1. — Raking and tonging for surf clams from a dory in shallow water 
 
 depths 3 
 
 2. — Types of rakes used for hand collection of surf clams 4 
 
 3. — "Long Island" hydraulic bar clam dredge of the type which became 
 
 popular with the Long Island clammers 5 
 
 4. — Early model hydraulic dredge showing sled under bag, one of the 
 early modifications which led to the development of the standard 
 
 dredge with its after-cage built of steel bars 5 
 
 5. — Photograph of largest hydraulic jet dredge in use today by the surf 
 clam industry. This is an 84-inch dredge used aboard the 136-ft 
 
 Gail Borden 6 
 
 6. — Gasoline-driven pump on the deck of a clamming vessel 7 
 
 7. — Classic 40-inch hydraulic jet dredge used by the majority of fishing 
 vessels operating along the coast of New Jersey and Maryland dur- 
 ing the late 1950's and up to the present time 8 
 
 8. — Drawing of a 48-inch hydraulic clam dredge built for clam survey 
 work aboard the National Marine Fisheries Service research vessels 
 
 Delaware and Delaware II 9 
 
 9. — Constant delivery pump system aboard the Gail Borden. 
 
 A — Separator, where all material transported up discharge hose 
 empties for washing and separation of clams from the rest of the 
 material. B — Escalator, where surf clams enter to be carried 
 up to sorting table or unit. C — Clam jetting water hose. D — 
 Air hose. E — Transporting hose, for carrying material from up- 
 take unit to separator. F — Waste discharge units, through which 
 other material is dumped back overboard 10 
 
 in 
 
10. — Constant delivery pump system dredge aboard the Gail Borden. 
 A — Clam jetting water supply hose. B — Compressed air hose. 
 Air is supplied through this hose to the uptake unit where it mixes 
 with the water in the hose, generating the upward movement of 
 water within the hose. C — Receiver. Material jetted out of 
 bottom and picked up by the dredge knife passes into this area 
 and then into the uptake of the discharge hose. D — Transport- 
 ing hose for carrying dredge material from receiver to separator ... 11 
 
 11. — Electrical submersible pump used for supplying water to dredge jets. 
 A — Submersible pump discharge opening, 8-inch inside diam. 
 B — Strainer surrounding pump, mesh size approximately 1-inch 2 . 
 Any object passing through this strainer will pass through pump . . 12 
 
 12. — Electrical submersible pump shown as mounted to 48-inch clam 
 dredge. A — 8-inch discharge, connected to header. B — Water- 
 tight electrical junction. C — Header 12 
 
 13. — Clamming vessel showing adaptation of gear to take dredge in over 
 
 the stern while steaming 13 
 
 14. — Stern chute clam dredge ramp used aboard Delaware II 14 
 
 15. — A converted shrimp boat. One of the several different vessel types 
 
 which were converted for surf clam dredging 15 
 
 IV 
 
History and Development of Surf Clam Harvesting Gear 
 
 By 
 
 PHILLIP S. PARKER, Fishery Biologist 
 
 National Marine Fisheries Service 1 
 
 Exploratory Fishing and Gear Research Base 
 
 Woods Hole, Massachusetts 02543 
 
 ABSTRACT 
 
 The development of harvesting gear for surf clams, Spisula solidissima, along 
 the eastern coast of the United States is reviewed from early times up to the 
 present. 
 
 Early clamming was done by hand using rakes or tongs, while today the in- 
 dustry depends upon large, efficient dredges operating from stable vessels. Little 
 gear development took place prior to World War II; however, since that time, the 
 industry has made rapid strides in the development of harvesting gear. Today 
 this trend is still very much in evidence, with gear constantly being modified for 
 adaptation to newer vessel types. 
 
 Most gear development work has been the result of the surf clam industry 
 itself. However, the Federal Government, in cooperation with industry, has de- 
 veloped several pieces of equipment for adaptation to clamming gear. 
 
 INTRODUCTION 
 
 The history of the development of harvest- 
 ing gear for surf clams, Spisula solidissima, 
 along the eastern coast of the United States 
 has been only touched upon by various authors 
 reporting on this species. However, to date, 
 no comprehensive description of the gear has 
 been written. Prior to World War II, the ef- 
 fort for development of this type of gear was 
 rather limited. Probably this was because the 
 harvesting equipment used at that time was 
 sufficient to maintain an adequate supply of 
 surf clams for both fish bait and the limited 
 market available for human consumption. The 
 World War II years, with the search for good 
 
 1 Formerly Bureau of Commercial Fisheries Explor- 
 atory Fishing and Gear Research Base, Gloucester, 
 Mass. 01930. 
 
 sources of high protein food by both Govern- 
 ment and industry, provided the impetus for 
 a tremendous increase in the market demand 
 for surf clams. Due to this demand, rapid de- 
 velopment of a variety of surf clam harvesting 
 gear followed. Many kinds of dredges were 
 devised by the industry before the hydraulic 
 jet dredge was developed. Different types of 
 hauling gear and boat sizes were also tried 
 during this period. 
 
 Today further radical changes are being 
 made to the so-called "standard" hydraulic jet 
 dredge in an effort to increase its efficiency. 
 Prior to 1963, clam gear research and devel- 
 opment were exclusively pursued by the surf 
 clam industry. This group had been respon- 
 sible for almost all of the changes in the de- 
 sign and modification of the clam harvesting 
 equipment. However, units of the National 
 
Marine Fisheries Service are now actively co- 
 operating with the surf clam industry and are 
 expending considerable time and effort in the 
 development of new types of clam harvesting- 
 gear suitable for use in exploratory surveys 
 and biological studies. 
 
 MANUAL COLLECTING METHODS 
 
 Hand Collecting 
 
 In all probability, the first surf clam harvest- 
 ing method employed in this country was that 
 practiced by the American Indian. Goode 
 (1887) quotes one of the earliest "tracts" writ- 
 ten upon our natural history, Wood's "New 
 England Prospect" (1634), which says that 
 along Nahant [Massachusetts] Beach, the sea 
 "after storms casts up greate store of greate 
 Clammes which the Indians taken out of their 
 shells conny home in baskets," and which also 
 says "Clammes as big as a halfe-penny loof, 
 which are greate dainties amongst the natives." 
 
 Another early and simple method of harvest- 
 ing was employed by farmers along the New 
 Jersey coast, who, after finding large quantities 
 of surf clams washed ashore by severe storms, 
 would shovel them into their wagons to be 
 hauled away for field fertilizer, for hog and 
 poultry feed, or for use as bait. At about the 
 same time (approximately 1878), a new fish- 
 ery was beginning at Dennisport, Mass., where 
 the surf clam was harvested by means of clam 
 rakes operated from dories which were either 
 hand or sail propelled. This method of dory- 
 hand raking for clams was only used out to 
 about V/o miles from shore (Fig. 1). The 
 rakes were made of iron with wooden handles 
 and measured from 20 to 27 ft in length; the 
 rake heads had 17 to 25 teeth and cost from 
 $5 to $8 apiece (Fig. 2). Most of the raking 
 was done in water depths of about 8 ft and 
 at ebb tide, although at times the fishermen 
 worked as deep as the length of the rake (ap- 
 proximately 18 ft) and tong handles would 
 permit (Goode, 1887). Potato forks or sim- 
 ilar instruments are used to harvest the surf 
 clam in certain areas of Canada. 
 
 Rakes 
 
 There are two types of rakes used in the 
 commercial fisheries today. These are the com- 
 mon clam rake and the bull rake (Fig. 2) . The 
 
 common rake is similar to a garden rake except 
 that the teeth are larger and sharper. It is 
 equipped with a wire mesh basket or "apron" 
 which holds the catch, and it is generally used 
 in very shallow water. (A modification is used 
 in Maine for gathering Irish moss (Dumont 
 and Sundstrom, 1961).) 
 
 The bull rake, used generally in New Eng- 
 land, is a large implement with a head between 
 20 and 30 inches wide (Fig. 2). It has long, 
 curved teeth which are about 9 inches long. 
 Unlike the common hand rake, the bull rake 
 does not have a basket or apron, its handle is 
 usually longer, and it is used in deeper water 
 than the hand rake (Dumont and Sundstrom, 
 1961). 
 
 Like the common rake, the bull rake has nu- 
 merous modifications. One of these is called 
 the Shinnecock rake. This rake is used only 
 in Maryland. Its long, curved teeth are pro- 
 gressively shorter toward the ends of the rake 
 head (Fig. 2) and are shaped to form a basket 
 in which the clams rest as they are raised from 
 the bottom (Dumont and Sundstrom, 1961). 
 
 Tongs 
 
 Another implement used during the early 
 days of the industry for gathering surf clams 
 was the hand tong (Fig. 1). Hand tongs are 
 actually a pair of rakes attached to the ends 
 of two long poles which are up to 20 ft in length 
 and are fastened together like a pair of scissors 
 with the fulcrum near the lower end. A bas- 
 ket-like frame is attached to the back side of 
 each rake in order to hold the catch (Dumont 
 and Sundstrom, 1961). 
 
 The production potential of rake and tong 
 gear was obviously limited, and before any 
 large expansion could take place in the surf 
 clam industry, development of more efficient 
 harvesting gear was necessary. 
 
 POWER COLLECTING METHODS 
 
 Scraper-Type Dredges 
 
 During the 1920's, scraper-type dredges 
 were developed which could be towed behind 
 power boats. These were usually 18 to 28 
 inches wide with a knife blade (rather than 
 teeth) located in front of a scoop which sloped 
 upward and backward toward a bag for hold- 
 
Figure 1. — Raking and tonging for surf clams from a dory in shallow water depths 
 
 ing the catch. The blade scooped into the 
 bottom to a depth of 6.5 to 9 inches. The so- 
 called "Sheepshead Bay" dredge had a more 
 or less straight leading edge to the knife and 
 was adjustable to a desired depth. These 
 dredges were towed by a rope, usually fastened 
 to a special stanchion, and were hauled aboard 
 either by a towing rope or by an additional 
 steel cable attached to the dredge. Both meth- 
 
 ods used a powered winch (Westman-). No 
 further significant changes were made in the 
 dredges for many years. However, the design 
 of some dredges became slightly modified, e.g., 
 the knife was rounded so that the leading edge 
 became an arc. 
 
 - Westman, J. R. 1946. On the origin, development 
 and status of the surf clam industry, 1943-45. New 
 York Conservation Department, Bureau of Marine 
 Fisheries. Unpublished manuscript, 10 p. 
 
Experiments were made with sleds under 
 the bag in attempts to clear the mud away 
 from the clams more rapidly. In spite of these 
 modifications, the scraper dredges piled up the 
 sand badly, which choked the forward parts 
 of the bag (Westman, see footnote 2). Be- 
 cause of the deficiencies in these dredges, as 
 well as undesirable results from their oper- 
 ation, experiments were conducted in the mid- 
 1940's by the surf clam industry which led to 
 the development of the more efficient hydraulic 
 jet dredge. 
 
 Hydraulic Dredges 
 
 The hydraulic jet dredge was developed by 
 jetting water directly into the conventional 
 "dry" dredge. The first units built were small 
 but were effective enough to prove their super- 
 iority over simple scraper dredges. One of the 
 main advantages of the hydraulic jet dredge 
 was its tremendous reduction in the number of 
 broken clams and damaged meats taken in the 
 catches. By utilization of the water jets, the 
 area that could be dredged during a tow was 
 more than doubled. This made possible the 
 commercial harvesting of clam populations of 
 far less density than was previously feasible. 
 Furthermore, regions of hard bottom which 
 were previously unsuitable for dredging now 
 became productive. 
 
 Many experiments using different types and 
 orientation of jets were made. Also, trials 
 using various types and sizes of water pumps, 
 as well as types and sizes of hose, were con- 
 ducted before the major difficulties were over- 
 come and boats of the commercial fleet were 
 converted to hydraulic jet dredge gear. 
 
 The most popular of the early types of 
 dredges was the "Long Island" hydraulic bar 
 clam dredge (Fig. 3) with three jets (West- 
 man, see footnote 2). Water was pumped to 
 these jets by a gasoline-driven pump located 
 aboard the fishing vessel through a 2^-inch 
 canvas fire hose. Special hose was later de- 
 veloped by the rubber industry for this spe- 
 cific purpose. This new hose could withstand 
 internal pressures up to 150 psi even with ex- 
 tensive outside wear from the abrasive action 
 of sand, gravel, etc. 
 
 Figure 2. — Types of rakes used for hand collection 
 of surf clams. 
 
 The development of the hydraulic jet dredge 
 did not stop here. Although the basic prin- 
 ciples remained unchanged, the size and effi- 
 ciency of the gear were continually increased 
 during the period 1945-65 (Fig. 4). The dis- 
 covery of large unexploited surf clam beds off 
 the coasts of Maryland and New Jersey (in 
 1949) resulted in a shifting of the center of 
 the industry from the Long Island area to the 
 coasts of New Jersey and Maryland. Because 
 of the increased availability of clams, the in- 
 dustry was able to expand rapidly and to in- 
 crease the size and efficiency of the gear used 
 to fish these beds. Dredge sizes have now 
 reached a maximum size of 84 inches in width 
 (Fig. 5). 
 
 Correspondingly, the size of water pumps 
 has been increased to maintain the proper 
 pressured flow of water required by these 
 larger dredges. The volume of the pumps has 
 
■S/Cf. 
 
 Hose 
 
 XO/Vh 
 
 tk 
 
 Figure 3. — "Long Island" hydraulic bar clam dredge of the type which became popular with the Long Island 
 clammers. (Drawn by Carl Rich after C. E. Petite and P. W. G. McMullon, Fish. Res. Board Can., Bull. 102, 
 Ottawa, 1955.) 
 
 SLED 
 
 DREDGE 
 
 KNIFE 
 
 Figure 4. — Early model hydraulic dredge showing sled under bag, one of the early modifications which led to 
 the development of the standard dredge with its after-cage built of steel bars. 
 
Figure 5. — Photograph of largest hydraulic jet dredge in use today by the surf clam industry. This is 
 an 84-inch dredge used aboard the 136-ft Gail Borden. Note size of auxiliary gear and deck equip- 
 ment required for the operation of this size dredge. Two 6-inch inside diam. water supply hoses are 
 required for the jetting action of this dredge on the bottom. 
 
 
Figure 6. — Gasoline-driven pump on the deck of a 
 clamming vessel. 
 
 been increased from a few hundred gallons 
 per minute up to 3,500 gpm. One commercial 
 boat is now using two pumps to supply the 
 required amount of water. Hose size has been 
 increased from 21/2- up to 61/^-inch inside di- 
 ameter with some boats doubling-up on the 
 smaller 6-inch hose. As the deck-mounted, 
 gasoline-driven pumps (Fig. 6) became inad- 
 equate, they were replaced with diesel-pow- 
 ered units installed below decks. This modi- 
 fication not only increased the available deck 
 space but also improved the operational safety 
 of the vessel. 
 
 The dredge most generally used between the 
 late 1950's and the present has been a 40-inch 
 model (Fig. 7). This size dredge is particu- 
 larly suited to the handling and towing capa- 
 bilities of most of the commercial vessels in 
 the clam fleet. 
 
 Although the size of this dredge is well 
 standardized, many minor modifications are 
 consistently being made in an attempt to im- 
 prove on its efficiency. These modifications 
 consist mainly of changes in the size and ar- 
 rangement of the water jets, variations in 
 placement and shape of the jet manifold, 
 changes in the volume and pressure of water 
 supplied to the jets, changes to the shape and 
 contour of the dredge knife, improvements in 
 the attachment of the knife to the dredge, 
 changes of the knife depth setting, variations 
 of towing speed, shape, and slope of the sled 
 
 floor, construction and attachment of the chain 
 bag, and towing attachment between the dredge 
 and sled. During this period of development, 
 local modifications to the dredges reflected dif- 
 ferences in the characteristics of the areas in 
 which they were being used. The shape of 
 the dredge might be slightly different or the 
 type of jet header and arrangement of the jets 
 might be different; also, the type and shape 
 of the knife could vary from area to area. Be- 
 cause of these variations, the physical state of 
 the hydraulic jet dredge can be considered to 
 have been almost constantly changing (Fig. 8) . 
 
 EXPERIMENTAL GEAR 
 
 As the commercial fishing effort increased 
 on the larger clam beds which were located 
 within easy distance from ports and processing 
 plants, these beds have sustained consistent and 
 heavy fishing pressure. As the production rate 
 over these beds leveled out, rich beds located 
 at greater distances from ports and plants have 
 been used. However, the balance maintained 
 between the fishing time to be gained or lost 
 by traveling shorter and longer distances, vs. 
 the production rate(s) of the various fishing 
 grounds, became an important consideration. 
 It now appears that in order to maintain the 
 desired production level, either faster boats or 
 more efficient fishing gear is needed. The lat- 
 ter proposal seems to be the more practical 
 solution. One approach to updating or other- 
 wise improving the gear and fishing method 
 is to adopt methods and gear used by other 
 marine industries for use in the surf clam 
 industry. 
 
 Early in 1963, a member of the surf clam 
 industry became interested in the development 
 of an airlift system based upon the principle 
 now used for collecting diamonds off the south- 
 ern coast of Africa. The principle involved is 
 that of pumping air down to the dredge where 
 the air is directed into the bottom of a large 
 hose extending from the dredge to the boat 
 deck. The air causes the mixed water-air col- 
 umn within the tube to become lighter than 
 the outside water and generates an upward 
 movement of the water within the hose. The 
 water flowing into the bottom of the hose to 
 replace the water which has moved upward 
 
Figure 7. — Classic 40-inch hydraulic jet dredge used by the majority of fishing vessels operating along 
 the coast of New Jersey and Maryland during the late 1950's and up to the present time. Note that 
 the dredge itself is all enclosed except for the bottom and forward section of its top. Loose aprons 
 built out of rings are used to enclose the space between the dredge and sled to prevent loss of clams 
 between the two units. In addition, chain attachments are used between the two units for towing 
 purposes. Attached to the sled is the chain bag built of 3-inch scallop rings and connectors. This 
 dredge is equipped with a straight edge knife. Many dredges use a V-shaped knife that floats on 
 springs and digs into the bottom only after the water to the jets is turned on. In use of spring-mount- 
 ed blades, the knife settles into a trough which is jetted out by the water. Dredges with this type 
 of blade also use a V-shaped manifold as compared to the straight manifold shown her"e. The clam 
 jetting hose shown has been built especially for clam jetting and has a 5-inch inside diam. 
 
3/j jg to support chain bay 
 
 ! -i — f^ 
 
 fyes at front of t/ed t. 
 
 Figure 8. — Drawing of a 48-inch hydraulic clam dredge built for clam survey work aboard the National Marine 
 Fisheries Service research vessels Delaware and Delaware II. 
 
 carries the material dredged from the bottom 
 with it. When fully developed, this system will 
 offer the possibility of continuous dredging 
 without interruption and loss of fishing time 
 for hauling, emptying, and resetting the dredge. 
 In addition, the catch can be constantly mon- 
 itored, and small beds can be effectively fished. 
 After preliminary investigation of the feas- 
 ibility of this method, Snow Canning Company 
 of Pine Point, Maine, began to assemble the 
 needed gear and equipment for building an air- 
 lift system on their vessel Gail Borden. After 
 building and pretesting component units of 
 the system, a working model was given lim- 
 ited fishing tests during the spring and sum- 
 mer of 1964. Many "bugs" were found, and 
 further effort for modifying the system to cor- 
 rect deficiencies continued. Near the middle 
 of 1965, the redesigned unit was ready for 
 
 further testing (Figs. 9 and 10). While some 
 minor deficiencies remained, test results were 
 encouraging enough to warrant the develop- 
 ment of a complete system for future clam 
 harvesting. 
 
 In addition to these developments, submers- 
 ible pumping systems have been developed to 
 replace the older type vessel-mounted pumping 
 systems used on all the commercial clam boats 
 today. Such a system has an electrically driven 
 submersible pump (of sufficient power and 
 rating) (Fig. 11) mounted on the forward end 
 of the clam dredge. The discharge end of the 
 pump is connected directly to the dredge man- 
 ifold (Fig. 12). Electrical energy is supplied 
 to the pump from a vessel-mounted generator 
 feeding power through a watertight power 
 cable which is stored on a deck-mounted hy- 
 draulically-driven reel. The main advantage 
 
Figure 9. — Constant delivery pump system aboard the Gail Borden. A — Separator, where all material trans- 
 ported up discharge hose empties for washing and separation of clams from the rest of the material. B — 
 Escalator, where surf clams enter to be carried up to sorting table or unit. C — Clam jetting water hose. 
 D — Air hose. E — Transporting hose, for carrying material from uptake unit to separator. F — Waste 
 discharge units, through which other material is dumped back overboard. 
 
 10 
 
\ 
 
 
 -. - f l #7 
 
 Figure 10. — Constant delivery pump system dredge aboard the Gail Borden. A — Clam jetting water supply 
 hose. B — Compressed air hose. Air is supplied through this hose to the uptake unit where it mixes with 
 the water in the hose, generating the upward movement of water within the hose. C — Receiver. Material 
 jetted out of bottom and picked up by the dredge knife passes into this area and then into the uptake of the 
 discharge hose. D — Transporting hose for carrying dredge material from receiver to separator. 
 
 11 
 
5 85# 
 
 Figure 11. — Electrical submersible pump used for sup- 
 plying water to dredge jets. A — Submersible pump 
 discharge opening, 8-inch inside diam. B — Strainer 
 surrounding pump, mesh size approximately 1-inch 2 . 
 Any object passing through this strainer will pass 
 through pump. 
 
 Figure 12. — Electrical submersible pump shown as 
 mounted to 48-inch clam dredge. A — 8-ihch dis- 
 charge, connected to header. B — Watertight elec- 
 trical junction. C — Header. 
 
 of this system is that it does away with hand- 
 ling the heavy hose required for the older 
 pumping system while requiring less work to 
 gear up. 
 
 Another recent innovation in clam gear is 
 the adaptation of the stern trawler type ves- 
 sel to clam dredging. This is accomplished by 
 modifying the handling gear so that the dredge 
 can be hauled in over the stern of the vessel 
 (Figs. 13 and 14). This method of handling 
 the dredge, along with some constant delivery 
 system, may prove to be the most efficient meth- 
 od of harvesting the sea clam in the future. 
 
 VESSELS 
 
 Small dories and skiffs were first used by 
 hand rakers and tongers to collect surf clams 
 from the shallow waters along the coast. As 
 mechanical methods for harvesting were de- 
 veloped during the 1920's, other types of boats 
 were utilized to handle the new type of equip- 
 ment. Party boats, skiffs, and conventional 
 small draggers became the backbone of the 
 commercial fleet. After widespread use of the 
 hydraulic jet dredge became established, larger 
 size vessels were needed. To meet the demand, 
 regular fishing vessels were converted in order 
 to accommodate this newer and more efficient 
 method of dredging. Previously, these larger 
 boats were generally used as shrimp boats (Fig. 
 15), oyster boats, fish draggers, sardine boats, 
 and conventional military boats. The range of 
 size for these boats is from 31 to 136 ft in 
 length and from 14 to 160 gross tons. Most 
 vessels are powered by diesel engines and are 
 operated, when dredging, by two- or three-man 
 crews, depending upon the size of the vessel. 
 
 SUMMARY 
 
 The development of surf clam harvesting 
 gear is traced from early times to the present. 
 
 During this period of time, very little devel- 
 opment work was accomplished prior to World 
 War II. After this, rather rapid strides were 
 made in development work by the surf clam 
 industry and in the past several years by the 
 Federal Government in cooperation with the 
 surf clam industry. 
 
 12 
 
The hydraulic jet dredge became the main 
 piece of surf clam harvesting gear in use today. 
 
 Many modifications have been made or in- 
 corporated into this piece of gear since its in- 
 ception. Today, the hydraulic jet dredge is be- 
 ing successfully operated from stern trawler 
 type of boats. 
 
 This gear has been adapted for use on many 
 different sizes and types of vessels, most of 
 which have been converted from some other 
 type of fishery. 
 
 LITERATURE CITED 
 
 DUMONT, W. H., and G. T. SUNDSTROM. 
 
 1961. Commercial fishing gear of the United States. 
 U.S. Fish Wildl. Serv., Circ. 109, iv + 61 p. 
 
 GOODE, G. B. 
 
 1887. History and methods of the fisheries. In G. 
 B. Goode, The fisheries and fishery industries of 
 the United States. U.S. Comm. Fish and Fish., 
 Sect. 5, Vol. 2: 581-615. 
 
 Figure 13. — Clamming vessel showing adaptation of gear to take dredge in over the stern while steaming. 
 
 L3 
 
Figure 14. — Stern chute clam dredge ramp used aboard Delaware II. 
 
 11 
 
.** \_ ** 
 
 Figure 15. — A converted shrimp boat. One of the several different vessel types which were converted for surf 
 
 clam dredging. 
 
 i:» 
 
 GPO 998-583 
 
349. Use of abstracts and summaries as communica- 
 tion devices in technical articles. By F. Bruce 
 Sanford. February 1971, iii + 11 pp., 1 fig. 
 
 350. Research in fiscal year 1969 at the Bureau of 
 Commercial Fisheries Biological Laboratory, 
 Beaufort, N.C. By the Laboratory staff. No- 
 vember 1970, ii + 49 pp., 21 figs., 17 tables. 
 
 351. Bureau of Commercial Fisheries Exploratory 
 Fishing and Gear Research Base, Pascagoula, 
 Mississippi, July 1, 1967 to June 30, 1969. By 
 Harvey R. Bullis, Jr., and John R. Thompson. 
 November 1970, iv + 29 pp., 29 figs., 1 table. 
 
 352. Upstream passage of anadromous fish through 
 
 navigation locks and use of the stream for spawn- 
 ing and nursery habitat, Cape Fear River, N.C 
 1962-66. By Paul R. Nichols and Darrell E. 
 Louder. October 1970, iv + 12 pp., 9 figs., 4 
 tables. 
 
 356. Floating laboratory for study of aquatic organ- 
 isms and their environment. By George R. 
 Snyder, Theodore H. Blahm, and Robert J. Mc- 
 Connell. May 1971, iii + 16 pp., 11 figs'. 
 
 361. Regional and other related aspects of shellfish 
 consumption — some preliminary findings from 
 the 1969 Consumer Panel Survey. By Morton 
 M. Miller and Darrel A. Nash. June 1971, iv -f 
 18 pp., 19 figs., 3 tables, 10 apps. 
 
UNITED STATES 
 DEPARTMENT OF COMMERCE 
 
 NATION \L OCEANIC a U.'AOSFHERIC ADMINISTRATION 
 
 NATIONAL A'^RINE FISHERIES SERVICE 
 
 SCIEN.IF'C P'JBLICUIONS STAFF 
 
 BLDG. 67, NAVAL GUP'uRT ACTIVITY 
 
 SEATTLE, WASHINGTON 98115 
 
 OFFICIAL BUSINESS 
 
 Hifiir