Table 2.— Mean seasonal high and low levels of adductor muscle glycogen in deepwater sea 

 scallop populations of the Gulf of Maine. 



Station 

 coordinates 



Lat. 



Long. 



Date of 

 collection 



Depth 

 (m) 



Bottom 



temperature 



CC) 



Sample 

 N 



Mean 



gonad 



volume 



(mL) 



Muscle 

 glycogen 

 0^9 g"^) 



'Deepwater station off Toothaker Ridge that was sampled whenever possible; other stations were selected 

 randomly during resource survey cruises. 



(thin shells and small adductor muscles), lack the 

 necessary glycogen reserves for successful spawn- 

 ing, and very probably resorb gametes. Moreover, 

 bottom temperatures seldom reach 10°C (Moimtain 

 and Jessen 1987), the lowest temperature at which 

 Placopecten magellanicus has been observed to 

 spawn (Culliney 1974). In a recent study of a single 

 deepwater sea scallop population in the Gulf of 

 Maine, Barber et al. (1988) report reduced fecun- 

 dity, followed by gamete resorption and a possible 

 minor spring spawning, in turn followed by redevel- 

 opment, continued resorption, and an abrupt fall 

 spawning attempt. Almost certainly, deepwater sea 

 scallops do not spawn successfully. Recruitment to 

 these beds, therefore, would be haphazard and 

 originate both from populations on nearby ledges 

 and from spatfall out of the Gulf of Maine gyre, from 

 upstream spawning populations. 



We have reported here that glycogen levels in 

 Placopecten magellanicus adductor muscle, meas- 

 ured during the annual peak period in late spring 

 and during the annual low period in winter, can in- 

 dicate scallop populations with little energy reserves 

 for successful spawning. In the case of the deep- 



water sea scallops in the Gulf of Maine, lack of avail- 

 able nutrients is undoubtedly the reason for their 

 low muscle glycogen. Still to be clarified are the 

 events leading to the 1984 failure of the Asbury 

 Park sea scallops to develop the necessary energy 

 reserves for spawning. 



Acknowledgment 



We are grateful to Vincent S. Zdanowicz and 

 Anthony L. Pacheco (NMFS, NEFC, Sandy Hook 

 Laboratory, NJ) for making possible the Asbury 

 Park collections, and to Thomas R. Azarovitz, Don- 

 ald D. Flescher, Henry W. Jensen, Malcolm J. Siver- 

 man, and their trawl-survey colleagues (NMFS, 

 NEFC, Woods Hole Laboratory, MA) for the deep- 

 water scallop collections. We also thank Laure A. 

 Devine, Todd M. Welch, and Beth C. Marks for 

 technical assistance. 



Literature Cited 



Barber, B. J., R. Getchell, S. Shumway, and D. Schick. 

 1988. Reduced fecundity in a deep-water population of the 



600 



