The Calico Scallop, Argopecfen gibbus 



By 



DONALD M. ALLEN and T. J. COSTELLO, Fishery Biologists 



National Marine Fisheries Service 



Southeast Fisheries Center 



Miami Laboratory 



Miami, Florida 33149 



ABSTRACT 



The calico scallop, Argopecten gibbus, supports a developing fishery off the southeastern 

 coast of the United States and in the Gulf of Mexico. Information is given on classification, 

 description, distribution, environment, relative abundance, reproduction, age and growth, 

 mortality, associated organisms, behavior, and the fishery. 



INTRODUCTION 



The calico scallop, Argopecten gibbus, a com- 

 mercially valuable shellfish, is fished in the At- 

 lantic Ocean off North Carolina and Florida and 

 in the northeastern Gulf of Mexico. Develop- 

 ment of the fishery has been slow^ and erratic, 

 due to problems related to stock availability and 

 processing. The apparent large concentrations 

 of scallops off the Florida east coast and the in- 

 troduction of scallop shucking and eviscerating 

 machines suggest, however, that the harvest of 

 calico scallops will increase in the next few years. 



Biologists at the National Marine Fisheries 

 Service, Southeast Fisheries Center, Miami Lab- 

 oratory, Miami, Fla., are studying the biology of 

 the calico scallop to determine which ecological 

 factors control distribution and abundance and 

 to predict seasonal and annual availability of 

 the harvestable stock. As a first step, this re- 

 port summarizes available information concern- 

 ing the biology and the fishery of the calico 

 scallop. 



BIOLOGY 



Classification 



' Contribution No. 207, National Marine Fisheries 

 Service, Southeast Fisheries Center, Miami Laboratory, 

 Miami, Fla. 



The calico scallop, Argopecten gibbtis (Linne) , 

 is a benthic marine pelecypod mollusk of the 

 family Pectinidae. Formerly known as Pecten 

 gibbiis or Aqidpecten gibbtcs, the species was 

 placed in the genus Argopecten by Waller 

 (1969). In the same genus he also placed two 

 closely related species that occur within the 

 range of the calico scallop. These are the nucleus 

 scallop, Argopecten nucleiis (Born) , and the bay 

 scallop, Argopecten irradians (Lamarck) , which, 

 unlike the calico scallop, are generally restricted 

 to very shallow water in the region of overlap- 

 ping distribution. Methods of separating these 

 scallops by shell characteristics were given by 

 Waller. A calico scallop is shown in Fig- 

 ure 1. 



The shell morphology of the calico scallop var- 

 ies with locality (Bullis and Ingle, 1959) and 

 perhaps environment (Waller, 1969). The sub- 

 specific status of a less convex form, A. gibbtis 

 portusregii, from buoys off South Carolina was 

 questioned by Waller. 



