Movement of Atlantic cod, Gadus morhua, tagged in the Gulf of Maine area

Over 22,000 Atlantic cod, Gadus morhua, were tagged with T-bar tags and rel eased in the Gulf of Maine area in 1984-97 and 2400 recovered tags were use d to interpret movement of tagged fish. Most of the releases were of adult fish made during the winter cod spawning season from aggregations found on known spawning banks. Recaptures by NAFO divisions were weighted with an an nual index of fishing effort to account for probability of recapture. At th e division level, very little exchange between the area east of 4X and the Gulf of Maine was evident. However, within the Gulf of Maine an exchange of about 15% between 4X and 5Z and somewhat higher between 4X and 5Y was appa rent. God tagged on Browns Bank and Georges Bank during the spawning season showed widespread dispersal both within their respective division and to a djacent divisions. The seasonal distribution of recaptures in 4X indicates aggregation for spawning followed by postspawning dispersal. The seasonal p attern for Georges Bank is less clear but there are indications of net loss to the 4X area. Distribution of recaptures from Georges Bank releases in 1 994 was similar to those observed for releases made in 1984-85. Results of the study were consistent with results from earlier tagging experiments and demonstrate substantial interaction of cod from different management areas . These findings may have implications for stock assessment models and mana gement objectives.