It is not possible to determine whether 

 the Nantucket Sound population is the result 

 of one or nnore dominant year classes. If 

 dominant year classes were based upon size 

 alone, the rather small difference in the 

 sizes of hard clanns might indicate a popula- 

 tion resulting from successful reproduction 

 in one or two years. Rough age readings 

 of the more distinctly lined shells indicate 

 a difference of 10 or nriore years in their 

 ages. The hard clams of the Sound are very 

 old (15 to 30 years ) and they grow, in terms 

 of shell length, very slowly. Blunting or 

 thickening of the shell lips can result in 

 individuals only a few millinneters different 

 in size, but several years apart in age. 



The preceding discussion would seem 

 to favor the second theory that these old 

 hard clams are the result of an accumulation 

 of a few offspring that survive each year. 

 The hydrographic data presented by Turner 

 (1957) indicate that, even if these deeper 

 water clams did spawn, the larvae would 

 likely be swept into the open ocean before 

 they developed to setting size. It is con- 

 ceivable that a few larvae come from the 

 inshore areas of Cape Cod, Marthas Vine- 

 yard, and Nantucket. Tidal currents could 

 carry a few larvae each year from these 

 inshore areas into the middle of the Sound. 

 Some of these larvae might be sufficiently 

 developed to set on suitable bottom, sur- 

 vive, and grow. Over a period of years a 

 commercially abundant population of hard 

 clams could be built up. But the abundance 

 of any particular age group would be ex- 

 tremely low and as was seen in this survey, 

 the young clams were not detected by the 

 sampling methods used. Only when the very 

 old individuals accumulated would the 

 abundance become great enough to be de- 

 tected. Studies in Greenwich Bay, Rhode 

 Island, indicate that concentrations of large 

 old clams can accumulate over a period of 

 years from small numbers of individuals 

 escaping the commercial fishery each year. 



The Nantucket Sound hard clam popu- 

 lations nnay, then, be the result of dominant 

 year classes or an accumulation over many 

 years of a very few offspring which set 

 and survive each year. Either of these 

 theories, the interaction of both, or some 

 other theory for which data are not yet 

 available, might explain how these popula- 

 tions came into existence. Predators un- 

 doubtedly further reduce the clam abund- 

 ance in the area. Samples taken during the 

 survey indicated the presence of at least 



the following six hard clann predators: 

 whelks, Busycon caniculatum and B. caricum; 

 cockles, Lunatia (f'olinices) heros and lolinices 

 dupUcatus; starfishes, Asterias sp.; and horse- 

 shoe crab, Limulus polyphemus , Other pred- 

 ators may also be present, but were not 

 caught in the samples. 



Since the hard clam concentrations of 

 Nantucket Sound are so low and therepopu- 

 lation of the area appears to be a slow 

 or doubtful process, the future of the present 

 fishery is uncertain. With present economic 

 conditions, fishermen consider tows yield- 

 ing less than 7 bushels unprofitable fishing. 

 Only 7 samples taken during the survey 

 indicated abundance greater than 7 bushels 

 per tow. It is estimated that ninety -five 

 24-hour fishing days would reduce these 

 areas to unprofitable population densities. 

 As the numbers of small hard clams to 

 augment present stocks appear to be non- 

 existent or at least very low, further 

 exploitation would only continue to lower 

 the concentrations of clams. 



CONCLUSIONS 



1. The abundance of hard clams in the areas 

 of Nantucket Sovmd surveyed is extremely 

 low as compared with other important 

 areas of the Atlantic coast. 



2. No hard clams below 60 millimeters 

 were caught in the survey by any of 

 the sampling methods used. 



3. No new areas of commercial abundance 

 were discovered by the survey. 



4. The future of the Nantucket Sound fishery 

 appears uncertain because hydrographic 

 conditions are unfavorable for spawning 

 and setting and because small hard clams 

 to augment the present stocks are scarce. 



LITERATURE CITED 



ATLANTIC STATES MARINE FISHERIES 

 COMMISSION. 



1958. Its 16th Annual Report, 79 pp. 



BELDING, DAVID L. 



1931. The quahaug fishery of Massa- 

 chusetts. CommonTwealth of Massa- 

 chusetts, Division of Fisheries & 

 Game, Marine Fisheries Series No, 

 2, 41 pp. 



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