SEA SCALLOP TAGGING EXPERIMENTS USING 

 MANNED-SUBMERSIBLES 



Paul Arthur Berkman 



Graduate School of Oceanography 



University of Rhode Island 



Narragansett, Rhode Island 02882-1197 



ABSTRACT 



Sea scallops were tagged and released on offshore ledges in 

 the Gulf of Maine to study their growth, movement, mortality and 

 shell deterioration. After one year, seventy percent of the 

 tagged live and dead scallops were recaptured with manned 

 submersibles. All of these scallops were found within a ten 

 meter radius of their release site. Growth of these scallops was 

 similar to estimates made from other studies, however their 

 mortality was higher. The deterioration of their shells showed 

 that the valves may be paired for periods substantially longer 

 than one year. These data suggest that the application of 

 "clappers", as a mortality estimator, should be reevaluated. 



INTRODUCTION 



Understanding the ecology of the sea scallop, Placopecten 

 magellanicus, is important for both science and resource 

 management. It is a conspicuous component of the coastal benthic 

 community in the western North Atlantic as well as a much enjoyed 

 seafood. Investigations have included laboratory studies 

 (Merrill 1961), the use of benthic trawls (Dickie 1955, Caddy 

 1979, Posgay 1979), SCUBA studies (MacDonald and Thompson 1985 

 and 1986), and submersible observations (Caddy 1970). 

 Submersibles were used in this study to manipulate sea scallop 

 tagging experiments on offshore scallop beds in the Gulf of 

 Maine. 



Live and dead tagged scallops were released for a period of 

 one year to evaluate shell deterioration and the validity of 

 "clapper" mortality estimates (Dickie 1955). The biomass of the 

 epizooic assemblages on the scallops also were investigated 

 because they may be related to how long a sea scallop has been 

 dead (Merrill et al . 1966). Scallop growth and mortality were 

 measured to determine the effect of the tags, and tagged scallop 

 movement was analyzed to assess whether results from tagging 

 studies can be generalized to the local scallop population. 



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