Table 34. Releases and returns for bluefin tuna 50 - 150 cm (mostly 50-100 cm) tagged on the continental shelf between 

 Cape Hatteras, North Carolina and Cape Ann, Massachusetts, June - October, by year of release, months at liberty, and 

 recapture area* 



Bay m October. This movement, if it 

 dfd occur, represented a range exten- 

 sion, rather than a migration, of the 

 entire mass of fish. Since 1964 

 catches of medium- sized tuna in all 

 waters north and east of Cape Cod 

 have been small or negligible. 



Information on the fall and win- 

 ter migrations of the medium-sized 

 bluefin is limited to deductions from 

 results of exploratory oceanic fish- 

 ing (Mather and Bartlett 1 962, Mather 

 1964b, Wilson and Bartlett 1967) 

 Commercial longline fishing in the 

 area has been much more extensive 



and provides valuable data on the 

 relative abundance of tuna in the area 

 by seasons (Wise and Davis 1973), 

 but size composition data for the 

 catches are limited, and have usually 

 been presented in such large tempo- 

 ral and areal strata as to be of little 

 \alue for this purpose 



Offshore exploratory longline 

 catches of bluefin north of latitude 

 35°N have consisted mainly of me- 

 dium fish and dense seasonal con- 

 centrations have been encountered 

 (Squire and Mather 1963) Consider- 

 ing these data collectively, the fol- 



lowing pattern for medium fish 

 emerges. After leaving the coastal 

 waters in mid autumn, fish of this 

 size concentrate in great numbers in 

 the canyons along the edge of the 

 continental shelf from the Hudson 

 Canyon off New York Harbor to the 

 northeastern end of Georges Bank 

 In winter, few were encountered in 

 these canyons, and the oceanic ex- 

 ploratory catch rates in this season 

 have been relatively low The data 

 indicate, however, that the bluefin 

 tend to accumulate in loose aggrega- 

 tions along the Gulf Stream front. 



126 



