Figure 78. Geographic distribution of bluefin tag release and recapture data from 

 Nova Scotian tagging studies. 



into the eastern North Atlantic and 

 the South Atlantic. Although con- 

 nections have been established be- 

 tween spring spawning areas in the 

 Gulf of Mexico and the Straits of 



Florida and summer nursery and feed- 

 ing areas off northwestern North 

 Amenca, a complete migratory pat- 

 tern has not emerged. We shall use 

 the temporal and areal distribution of 



Table 32 Releases and returns for giant (>122 kg) bluefin tuna, Thunnus 

 thynnus, tagged in New England coastal waters by years of release and time at 

 large. 



■Includes 6 releases of, and 4 1973 and 1 1975 returns from fish tagged while 



free swimming. 



""Includes 3 releases of, and 3 returns from, fish tagged while free swimming 



longline catches and the observed re- 

 lationships of the bluefm's distribu- 

 tion and migratory habits to the ocean 

 currents in completmg a hypotheti- 

 cal model for the migrations of large 

 western Atlantic bluefin. 



The limits of the western Atlan- 

 tic area in which large bluefin spawn 

 have not been established, but the 

 spawning grounds may mclude most 

 of the deep (over 200 m) waters be- 

 tween latitudes 18°N and 33°N, and 

 longitude 17°W and the coast (see 

 Section VD3) 



The only thoroughly documented 

 migration of large bluefin within this 

 supposed spawning area is their 

 northward passage through the Straits 

 of Florida in May and June. This 

 movement may be traced visually 

 from boats or aircraft for about 65 

 nautical miles (120 km) along the 

 northwestern edge of the Great 

 Bahama Bank from Orange Cay to 

 Great Isaac (Figure 29) when condi- 

 tions are favorable (Farrington 1939, 

 personal observations from U.S. 

 Coast Guard Aircraft by L. R. Rivas, 

 H. A. Schuck and F. J. Mather in 

 May-June 1951, Rivas 1955, Mather 

 1964b). A continuation of this mi- 

 gration along the 40 nautical mile 

 (74 km) western edge of the Little 

 Bahama Bank has also been observed 

 (personal observations by the semor 

 author at Memory Rock and 

 Matanilla Shoal, June 1966, catches 

 off West End, Grand Bahama, per- 

 sonal communications) The senior 

 author also sighted and baited schools 

 of giant bluefin which were traveling 

 northward on the surface at the west- 

 ern end of the Northwest Providence 

 Channel, between the Great and Little 

 Bahama Banks, in May-June 1968. 

 This unusual observation was a good 

 indication of the continuity of this 

 migratory route. 



Other migrations within the 

 spawning areas may be deduced from 

 the times and locations of catches, 

 sightings and/or the destruction of 

 equipment of anglers fishing for 

 billfishes and other less powerful 

 game, as well as occasional appear- 

 ances of schools of bluefin. 



The Windward Pa.ssage appears 

 to be a focal point in the migrations 

 of giant bluefin into the spawning 

 aiea. Large fish, including some with 



119 



