Figure 3.--Dumping the dredge 



Three 50 -minute tows were made over 

 bottom previously sampled by three 20- 

 minute tows to determine if catches were 

 proportional to time. The numbers of clams 

 caught for each 50 -minute tow were 640, 

 665, and 334. The corresponding 20-minute 

 tows caught 311, 319, and 189 clams re- 

 spectively. The catches of the 20-minute 

 tows converted to 50-minute tows were 

 larger than the catches of the 50-minute 

 tows by 21.5, 19.9, and 41.5 percent re- 

 spectively. In other words, the catches of 

 clams may not be proportional to time; 

 however, the variation in catch for each of 

 the above tows was large. 



Since so fc'w observations were obtained 

 upon -which to base a decision, the conver- 

 sion factor of 2 1/2 was used, with the 

 realization that the actual concentrations 

 of clams may be less than is reported. 

 As will be seen, a lower conversion factor 

 would not affect the general conclusions 

 about the fishery. 



As the jet dredge, used for the major 

 part of the survey, retains only the largest 

 sizes, two different techniques were used to 

 sample clams less than 90 millimeters 

 (3 1/2 inches) in length. First, the rear 

 cage of the dredge was lined with 1/2 -inch 

 mesh wire hardware cloth, and 3 -inch 

 stretched mesh cotton netting was laid in 

 the bag to obstruct the ring openings. The 

 unwashed contents of eachdrag were dumped 

 onto the deck and searched for small clams. 

 Second, as it proved impossible to line the 

 dredge complfetely, a small clam-shell 

 bucket was used from the PHALAROFE II, to 

 sannple two areas. The clam-shell bucket 

 samples about 5 square feet of bottom and 

 has been used successfully in Narragansett 

 Bay, Rhode Island to sample all sizes of 

 hard clams (Stickney and Stringer 1957). 

 The two areas in Nantucket Sound sampled 

 with the clam-shell bucket included stations 

 that had been found to have dense concen- 

 trations of clams. Ninety -eight samples 

 were taken in a grid pattern, separated 

 from one another by 900 feet in both 

 north-south and east -west directions, from 

 each 1 - by 2 -mile area. 



Numerous observations were recorded 

 during the survey. All hard clams caught 

 were counted. When a sample contained 

 more than 1 bushel of clams, the lengths 

 of clams in 1 bushel were measured. H 

 less than a bushel of clams were caught, 

 the whole sample was measured. Observa- 

 tions were made of the sediments adhering 

 to the dredge after each drag, presence of 

 other animal species, water temperature 

 at the surface and bottom, and the total 

 amount of clam breakage. Meat yield was 

 determined for some samples in terms of 

 pounds of shucked, drained meats per 80- 

 pound bushel of whole clams. 



ABUNDANCE AND DISTRIBUTION 



Figure 4 shows the Nantucket Sound 

 area, the location of the various shoals and 

 the 5 -fathom -depth contour line. This line 

 seems to separate roughly the hard clam 

 producing areas since most of the clams 

 were found below the 30-foot depth. 



The locations of 214 stations sampled 

 with the unlined jet dredge are presented 

 in figure 5. Each station represents a tow 

 of about 1/2 mile, made in 20 minutes. 

 The abundance of clams, in bushels per 

 1 -hour tow, is also included for each station. 



