Asbury Park sea scallops the following winter were 

 within the normal range (200-300 /ig g^^) observed 

 for sea scallop populations over those same years 

 of monitoring. 



In 1982 and 1983, the Asbury Park sea scallops 

 were apparently adequately fed during the spring 

 months, although glycogen levels were less than one 

 third of those seen in 1981 and had no discernible 

 peak. Muscle glycogen in the winter months of 1983 

 and 1984, however, was sufficiently high in both 

 sexes (as compared with postspawning levels for this 

 population, and with mean winter levels in other 

 populations) to prompt the suspicion that gamete 

 resorption had taken place, and that the 1983 

 spawning season had not been very successful. 

 Moreover, although an intensive weekly sampling 

 was performed in May and June 1984, we did not 

 observe the normal seasonal increase in muscle 

 glycogen; instead, the values resembled those of a 

 typical winter low. When spring values for each year 

 are compared with the subsequent winter's post- 

 spawning values (Table 1), a picture emerges of 

 declining nutritional status from 1981 to the end of 

 the study. 



It is possible, of course, that the spring values in 

 1982 and 1983 were more typical for this popula- 

 tion and that spring values for 1981 may have been 

 unusually high. The latter phenomenon could have 

 been the result of especially heavy phytoplankton 

 blooms, or of oceanic currents favorable to the bot- 

 tom settlement of planktonic nutrients. Certainly 

 the most important single variable is nutrient 

 availability. 



The 1984 glycogen levels indicated either that 

 little or no food was available to the sea scallops (at 

 30 m), or that they were not assimilating normally 

 any food that was available. This phenomenon has 

 yet to be explained satisfactorily, because the phyto- 

 plankton bloom in the area that year was extensive 

 (J. O'Reillyi). Steven K. Cook^ had suggested that 

 some oceanographic event, such as the inshore intru- 

 sion of an offshore water mass known as the "cold 

 pool" (e.g. Hopkins and Garfield 1979) may have 

 caused an unusually early formation of a thermo- 

 cline, one that effectively prevented settlement of 

 planktonic detritus to the bottom. Whatever the 

 reason, the Asbury Park sea scallops showed dimin- 

 ishing glycogen reserves for spawning from 1981 

 to the end of the study in 1984. Either planktonic 



nutrients were not reaching that population, or food 

 was available but the sea scallops were not feeding 

 or assimilating properly. 



If the latter should be the case, it is perhaps rele- 

 vant that the Asbury Park sea scallop population 

 lies approximately 24 km downstream from the 

 Christiaensen Basin, where general current patterns 

 are southwesterly. Several active dumpsites are 

 located in the Christiaensen Basin, including those 

 for New York's sewage sludge and dredge spoils, 

 where copper is a major contaminant (see Steimle 

 et al. 1982). Moreover, as little as 10 ^g L"^ copper 

 in the water column has been shown to interfere 

 with gamete production and maturation (resorbing 

 gametes) and probably also with feeding or nutri- 

 ent assimilation in Placopecten magellanicus (Gould 

 et al. 1985, 1988). Chemical analysis of tissues from 

 these same Asbury Park sea scallops is under way, 

 to determine whether metal levels were sufficient- 

 ly elevated to induce this effect. 



Deepwater Scallops 



A data pattern for muscle glycogen similar to that 

 seen in the Asbury Park sea scallops for 1984 has 

 been observed in deepwater sea scallops taken from 

 various sites in the Gulf of Maine (Table 2). These 

 sea scallop beds were sampled randomly during the 

 NEFC trawl survey cruises, and one fixed station 

 was sampled seasonally during NEFC NEMP 

 cruises (Gould 1981, 1983). Sea scallops taken from 

 waters >110 m deep routinely showed very low 

 glycogen levels throughout the year, the highest an- 

 nual levels being reached in December. In the fall, 

 vertical mixing of the subsurface and intermediate 

 water increases to as deep as 150 m (McLellan et 

 al. 1953; Colton 1968; Hopkins and Garfield 1979; 

 Mountain and Jessen 1987), with the disappearance 

 of any strong thermocline. In a recent comparison 

 of food resources in shallow (20 m) and in deepwater 

 (180 m) populations, Shumway et al. (1987) observed 

 that a number of intact planktonic algal species 

 reached the deepwater sea scallops after the fall 

 phytoplankton bloom; this late annual food source 

 "may provide just enough energy to sustain the 

 population." On the whole, however, nutrient avail- 

 ability is very low at such depths, as indicated by 

 the absence of chlorophyll in the deeper water 

 column (J. O'Reilly^). 



Deepwater sea scallops are visibly undernourished 



U. O'Reilly, Northeast Fisheries Center Sandy Hook Laboratory, 

 National Marine Fisheries Service, NOAA, P.O. Box 428, High- 

 lands, NJ 07732, pers. commun. October 1984. 



^Steven K. Cook, National Weather Service, 2980 Pacific High- 

 way, San Diego, CA 92101, pers. commun. March 1984. 



^J. O'Reilly, Northeast Fisheries Center Sandy Hook Laboratory, 

 National Marine Fisheries Service, NOAA, P.O. Box 428, High- 

 land, NJ 07732, pers. commun. May 1985. 



599 



