An Assessment of Juvenile and Adult Sea Scallop,Placopecten magellanicus, Distribution in the Northwest Atlantic using High-Resolution Still Imagery

Abstract

Recent surveys using high-resolution imagery have enabled improved detection of Atlantic sea scallops, Placopecten magellanicus, between 10 mm and 65 mm in shell height, allowing the observation of juvenile scallops in the wild, which was previously difficult. Using these high-resolution images from 2008 and 2009 surveys of Georges Bank and the Mid-Atlantic Bight, the distribution and crowding levels of juvenile and adult scallops were examined. Mean crowding values revealed differences in small-scale distribution of scallops that were undetectable with density estimates. Juveniles on Georges Bank were 2.6–3.9 times more crowded than adults, and 2.9–7.4 times more crowded than juveniles and adults in the Mid-Atlantic Bight. The increased crowding of juvenile scallops on Georges Bank may be the result of differences in substrate, sea star interactions, and abundance of filamentous flora and fauna. The incorporation of high-resolution imagery into optical surveys represents an important development in the advancement of survey techniques because it has the potential (1) to quantify year class strength of 1-y-old scallops more accurately; (2) to improve growth, mortality, and biomass estimates in stock assessments; and (3) to advance our understanding of scallop ecology, including recruitment processes and population dynamics.