Acknowledgments 



I thank R. J. Zimmerman and K. N. Baxter, 

 Southeast Fisheries Center Galveston Laboratory, 

 National Marine Fisheries Service, for directing the 

 specimen to me. J. C. Harshbarger aided with 

 sources of information on pathology, and I. Perez 

 Farfante with B. B. Collette critically reviewed the 

 manuscript. Keiko Hiratsuka Moore rendered the 

 illustration. 



Literature Cited 



Bateson, W. 



1894. Materials for the study of variation treated with 

 especial regard to discontinuity in the origin of species. 

 MacMillan and Co., London and New York, xvi + 598 p. 

 Couch, J. A. 



1978. Diseases, parasites, and toxic responses of commercial 

 penaeid shrimps of the Gulf of Mexico and south Atlantic 

 coasts of North America. Fish. Bull., U.S. 76:1-44. 

 Herrick, F. H. 



1896. The American lobster. A study of its habits and devel- 

 opment. Bull. U.S. Fish Comm. 15(for 1895):l-252, pis. 

 A-J, 1-54. 

 1911. Natural history of the American lobster. Bull. U.S. 

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 Johnson, P. T. 



1968. An annotated bibliography of pathology in inverte- 

 brates other than insects. Burgess Pub. Co., Minneapolis, 

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Johnson, P. T., and F. A. Chapman. 



1969. An annotated bibliography of pathology in inverte- 

 brates other than insects. Suppl. Cent. Pathobiol., Univ. 

 Calif. Irvine, Misc. Publ. No. l:i-ii, 1-76. 



Pauley, G. B. 



1974. A bibliography of pathology in invertebrates other than 

 insects from 1969-1972. NOAA-NMFS Middle Atlantic 

 Coastal Fisheries Center Pathology Investigations, Oxford, 

 MD, Informal Rep. No. 24:i-ii, 1-122. 

 PEREZ Farfante, I. 



1980. Revision of the penaeid shrimp genus Penaeopsis 

 (Crustacea: Decapoda). Fish. Bull., U.S. 77:721-763. 

 Ryder, J. A. 



1886. The monstrosities observed amongst recently hatched 

 lobsters. Am. Nat. 20(8):742-743. 

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Austin B. Williams 



Systematics Laboratory 



National Marine Fisheries Service, NOAA 



National Museum of Natural History 



Smithsonian Institution 



Washington, DC 20560 



NOTE ON MUSCLE GLYCOGEN AS 



AN INDICATOR OF SPAWNING POTENTIAL 



IN THE SEA SCALLOP, 



PLACOPECTEN MAGELLANICUS 



During the reproductive cycle of the Atlantic sea 

 scallop, Placopecten magellanicus, glycogen levels 

 rise and fall in the hemolymph (Thompson 1977) and 

 in the adductor muscle (Robinson et al. 1981; Gould 

 1983), reflecting the buildup of glycogen reserves 

 in the muscle and their later transfer to the gonad. 

 Muscle glycogen normally rises to a yearly peak in 

 spring after the phytoplankton blooms, then is trans- 

 ferred to the gonad for gamete differentiation and 

 maturation (Robinson et al. 1981). The glycogen 

 transfer is followed by an increase in size of the 

 maturing gonad and a loss of muscle weight (Gould 

 1983). During the autumnal algal blooms, glycogen 

 levels in the muscle rise again slightly and drop 

 thereafter to an annual low during the winter 

 months, when the small energy reserves are used 

 for basal maintenance and to initiate gametogenesis. 



Glycogen reserves from the muscle and lipid 

 reserves from the digestive gland are the major 

 sources of stored energy supplied to the scallop 

 gonad. High spring glycogen levels most drama- 

 tically indicate the degree of buildup of energy 

 stores used to fuel gamete differentiation and 

 maturation, whereas low winter muscle glycogen 

 levels correspond to the postspawning exhaustion 

 of reserves. Winter values higher than the normal 

 range for any given population, therefore, could in- 

 dicate an unusually large and extended period of 

 nutrient availability, but more probably would sug- 

 gest resorption of gametes. 



We suggest, therefore, that the spring peak and 

 the winter ebb of muscle glycogen be used as meas- 

 ures of the relative spawning potential and spawn- 

 ing success, respectively, for Placopecten. Sampling 

 during these two seasons may readily provide infor- 

 mation on the recruitment contribution of different 

 scallop populations. 



Timing of the seasonal high and low values for this 

 metabolic parameter can vary by several weeks from 

 year to year, reflecting the timing and intensity of 

 phytoplankton blooms (themselves dependent on 

 other environmental variables), and the time and 

 degree of success in spawning. To obtain a practical 

 data base for this major measure of seasonal energy 

 reserves, therefore, we sampled a single bed of sea 

 scallops off Asbury Park, NJ, on a year-round 

 monthly basis for 3V2 years. In examining mean an- 

 nual high and low muscle glycogen values for these 

 scallops, data were averaged for animal collections 



FISHERY BULLETIN: VOL. 86, NO. 3, 1988. 



597 



