842 



Abstract.-Over 22,000 Atlantic cod, 

 Gadus morhua, were tagged with T-bar 

 tags and released in the Gulf of Maine 

 area in 1984-97 and 2400 recovered 

 tags were used 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. Re- 

 captures by NAFO divisions were 

 wejghted with an annual index of fish- 

 ing effort to account for probability of 

 recapture. At the division level, very 

 little exchange between the area east 

 of 4X and the Gulf of Maine was evi- 

 dent. However, within the Gulf of 

 Maine an exchange of about 15% be- 

 tween 4X and .5Z and somewhat higher 

 between 4X and 5Y was apparent. Cod 

 tagged on Browns Bank and Georges 

 Bank during the spawning season 

 showed widespread dispersal both 

 within their respective division and to 

 adjacent divisions. The seasonal distri- 

 bution of recaptures in 4X indicates 

 aggregation for spawning followed by 

 postspawning dispersal. The seasonal 

 pattern 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 1994 

 was similar to those observed for re- 

 leases made in 1984-85. Results of the 

 study were consistent with results from 

 earlier tagging experiments and dem- 

 onstrate substantial interaction of cod 

 from different management areas. 

 These findings may have implications 

 for stock assessment models and man- 

 agement objectives. 



Movement of Atlantic cod, Gadus morhua, 

 tagged in the Gulf of Maine area 



Joseph J. Hunt 



Biological Station 



St. Andrews, New Brunswick EGG 2X0. Canada 



E-mail address hunt||ia'mardfo mpogcca 



Wayne T. Stobo 



Bedford Institute of Oceanography 

 Dartmoutti, Nova Scotia B2Y 4A2. Canada 



Frank Almeida 



Northeast Fisheries Science Center 

 National Marine Fisheries Service, NOAA 

 Woods Hole, Massachussetts 02543-1097 



Manuscript accepted 16 November 1998. 

 Fish. Bull. 97:842-860 ( 1999), 



The Atlantic cod (Gadus morhua ) is 

 a demersal species with a wide 

 Northwest Atlantic geographic 

 range extending from the Gulf of 

 Maine in the south to the Davis 

 Strait in the north ( Scott and Scott, 

 1988), It is one of the most important 

 commercially exploited groundfish 

 species in Atlantic waters off Canada 

 and the eastern U,S, region, and cod 

 stocks have supported fisheries in the 

 Gulf of Maine since the 1700s (Ser- 

 chuk and Wigley, 1992), 



The Gulf of Maine area, as de- 

 fined in this study, includes waters 

 of the Bay of Fundy, Georges Bank 

 to 7r'41'W, and the Scotian Shelf 

 west of 63' 20' W, an area of approxi- 

 mately 150,000 km-. There are four 

 fisheries management units identi- 

 fied for Atlantic cod in this area, 

 based on known areas of spawning 

 aggregation and commercial fisher- 

 ies (Halliday et al., 1986), Geo- 

 graphic boundaries of North Atlan- 

 tic Fisheries Organisation (NAFO) 

 divisions and the U.S. National 

 Marine Fisheries Service (NMFS) 

 and Canadian Department of Fish- 

 eries and Oceans (DFO) unit areas 

 ( Fig, 1 ) are used to approximate the 

 distribution of the stocks. The 



present management units are di- 

 vision 4X, subdivision 5Ze in unit 

 areas j and m (Canada), subdivision 

 SZw+SAB (USA) and division 5Y. 

 The area is also divided by the In- 

 ternational Maritime Boundary 

 (1MB) between Canada and the 

 United States, established in 1984, 

 Halliday and Pinhorn (1990) have 

 provided an extensive review of the 

 basis for existing statistical areas 

 used to report fisheries activities 

 and note that unit areas were es- 

 tablished in the early 1970s, 



Population characteristics of the 

 four cod stocks have been reported 

 by Canada (Clark 1996; Hunt and 

 Buzeta 1996) and by the United 

 States (NEFSC, 1994). Stock abun- 

 dance has shown substantial varia- 

 tion in the last fifteen years and a 

 broad range of recruitment. In gen- 

 eral, all the stocks have declined 

 from the long-term average abun- 

 dance and, with the exception of the 

 4X stock, appear to be at low levels 

 of spawning stock biomass. 



Numerous tagging studies have 

 been undertaken to examine move- i 

 ment of cod in the Gulf of Maine 

 area. Hunt and Neilson (1993) pro- 

 vided a synopsis of tag-recapture 



