FISHES, MACROINVERTEBRATES, AND 



THEIR ECOLOGICAL INTERRELATIONSHIPS WITH 



A CALICO SCALLOP BED OFF NORTH CAROLINA 



Frank J. Schwartz and Hugh J. Porter 1 



ABSTRACT 



A 1972 study documented the fishery, fish and macroin vertebrate faunas, possible predators, and the 

 ecological interrelationships of the offshore North Carolina calico scallop, Argopecten gibbus, bed(s). 

 Environmental data of water temperature, salinities, chlorophyll a, water current direction, sediment 

 grain size, and organic composition were obtained aboard commercial and chartered research vessels. 

 Water temperatures progressed seasonally from 12° to 26° C while bottom salinities varied between 31 

 and 37"/ooyet were not radically different from the surrounding habitats. Chlorophyll a data suggested a 

 fairly stable but low plankton fauna over the bed(s) except for June and late October. Little or no 

 differences in bottom type within or without the bed(s) were noted on the basis of sediment particle size, 

 grain size, skewness, or sorting coefficients. Scallops grew faster in the experimental bed than in the 

 commercial bed but little could be found to account for their differences in size. Some 111 species of 

 fishes were captured over the bed(s). Of a vast moving fish fauna, 33 species dominated the catches. Of 

 46 species with food in their stomachs, 20.4% feed on scallops with only 9 species considered scallop 

 predators. Bothids, soleids, rajids, labrids, dasyatids, and myliobatids were not active scallop pred- 

 ators. Halichoeres eaudalis appeared in October when the fishery collapsed economically. Of 12 

 species of echinoderms, the sea stars Luidia clathrata and Astropecten articulatus were active scallop 

 predators. While less abundant, 21 additional invertebrates were also suspected predators. Luidia 

 clathrata and A. articulatus abundance on the beds remained high throughout the season; however, 

 abundance off the beds was somewhat lower. No one factor has yet been found that made the North 

 Carolina calico scallop beds unique, why they existed, or were productive in 1972. 



Three commercial species of scallops occur in 

 North Carolina: the Atlantic deepwater scallop, 

 Placopecten magellanicus (Gmelin), the shallower 

 offshore calico scallop, Argopecten gibbus (Linne), 

 and the inshore bay scallop, A rgopeeten irradians 

 (Lamarck). The offshore calico scallop fishery, 

 while yielding varying quantities of harvestable 

 scallops (Table 1), has alternately experienced 

 good and bad years of production (Lyles 1969; 

 Cummins 1971; Chestnut and Davis 1975). The 

 disappearance of calico scallops from an area, 

 whether off North Carolina, Florida, or elsewhere, 

 is common knowledge (Bullis and Ingle 1959; Hu- 

 lings 1961; Anonymous 1962; Kirby-Smith 1970; 

 Roe et al. 1971; Porter and Wolfe 1972). Off North 

 Carolina the causes of scallop fluctuations and 

 production have been attributed to mortalities, 

 migration, poor larval transport from elsewhere, 

 introduction of scallop shucking and eviscerating 

 machines, or overfishing (Webb and Thomas 1968; 

 Lyles 1969; Cummins and Rivers 1970; Kirby- 



TABLE 1. — North Carolina calico scallop production, 1959-75. ' 

 [No production 1962-64, 1968-69, and 1974-75.] 



'Data supplied by the National Marine Fisheries Service Statistical Office. 

 Beaufort, N.C., and Chestnut and Davis 1975. 



Smith 1970; Cummins 1971; Allen and Costello 

 1972). This report documents the fish and mac- 

 roinvertebrate faunas, possible predators, and 

 their ecological interrelationships with the scallop 

 bed(s) that supported the 1972 fishery. 



NORTH CAROLINA 

 CALICO SCALLOP FISHERY 



'Institute of Marine Sciences, University of North Carolina, 

 Morehead City, NC 28557. 



Manuscript accepted November 1976. 

 FISHERY BULLETIN: VOL. 75, NO. 2, 1977. 



While A. gibbus occurs in the western North 

 Atlantic from the northern side of the Greater 

 Antilles and throughout the Gulf of Mexico to 



427 



