







y \ ,. 



-- _--*' 





-'' 



40°3C 









mow 



3 



/7 -x / 



; / V 



ft 2 / ,■' 





\ 1 ■' 



\ ! / 





H0| 



4020 



NEW 

 JERSEY 



JUVENILES 



~J l-39/ m 2 

 ADULTS 



4010 



7400' 

 ' 



73°50' 



73°40' 



Figure 18. — Distribution and abundance of Arctica islandica in the New York 

 Bight apex. 



Loosanoff (1953). Rapid gonad growth took place during spring 

 and spawning began at a temperature of 13.5 °C in late June or early 

 July and continued into October. Landers (1973) found that the 

 planktonic larvae reared at 10°C metamorphosed in about 60 d 

 when they were about 200 jim in length. His attempts to ripen clams 

 out of season met with limited success. 



Merrill et al. (1969) stated that it is not possible to estimate the 

 age of adults. However, obvious annual rings indicate that 

 commercial size individuals are over 10 yr old. Thompson 1 sug- 

 gested that this species may even live over 60 yr, an estimate based 

 on refined growth ring analysis. 



ADDITIONAL INFORMATION: In laboratory tanks and in the 

 sea, it has been shown that A. islandica can exhibit a high degree of 

 respiratory independence under hypoxic conditions. Under these 

 conditions, the periods the clam spends at the surface alternate with 

 periods when it is buried several centimeters below the surface of 

 the sand, during which the animal respires anaerobically. There is 

 no obvious rhythmicity to this behavior; the durations of periods 

 spent beneath the surface are variable, even in the same animal, but 

 they normally last between 1 and 7 d. As in other species studied, 

 respiratory independence in A. islandica increases markedly with 

 increasing body size and can also be modified by temperature and 

 physiological condition (Taylor and Brand 1975a, b; Taylor 1976). 



The ocean quahog industry has developed more slowly than that 

 of the surf clam, Spisula solidissima. It was not until the 1970s that 



a vigorous commercial ocean quahog fishery developed, primarily 

 to supplement diminishing supplies of the more desirable surf 

 clams. 



Cerastoderma pinnulatum (Conrad, 1831) 



DESCRIPTION: Northern dwarf cockle; 0.6-1.3 cm in length, 

 thin, with 22-28 wide, flat ribs which have delicate, arched scales 

 on the anterior slope of the shell. Exterior cream colored, interior 

 glossy and white (Abbott 1974). Cockles are active animals, with 

 larger species able to leap several inches off the bottom (Abbott 

 1968). 



DISTRIBUTION: 

 1974). 



Labrador to off North Carolina (Abbott 



HABITAT: Because of their very short siphons, cockles must live 

 near the surface of the substrate and consequently are affected by 

 shifting sands and, in shallow water, by great temperature changes. 

 They are commonly collected from 6 to 183 m (Abbott 1968, 

 1974). Franz (1976) stated that Cerastoderma pinnulatum is char- 

 acteristic of coarse sand in Long Island Sound. 



In the apex of the New York Bight. C. pinnulatum was collected 

 from depths of 22-37 m. It occurred in all sediment types but was 

 most common in high organic fine sands (Fig. 19: Table 1). 



FEEDING ECOLOGY: C. pinnulatum possesses short separate 

 siphons and feeds on organic matter suspended in water (Sanders 



7 Ida Thompson, Princeton University, Princeton. NJ 08540, pers. commun 

 October 1979. 



Figure 19. 



-Distribution and abundance of Cerastoderma pinnulatum in the 

 New York Bight apex. 



13 



