Figure 81. Geographic distnbution ofbluefin lag release and recapture data from 

 middle Atlantic taggmg studies. illuslraUng inshore-offshore movements 



Jr., W F. Rathjen and P. C. Wilson, 

 personal communications). The pres- 

 ence of small bluefin in the area 

 bounded by latitudes 40° and 45°N 

 and longitudes 45° and 70°W has 

 been documented, however, by 

 Shingu and Hisada (1976). About 90 

 percent of their sample of Japanese 

 longline catches in this quadrilateral 

 in January-February 1975, consisted 

 of small (less than 32 kg) fish, about 

 half of which were in their third year 

 of life. 



While in this wintenng area, the 

 small bluefm remaui at subsurface 

 levels (perhaps about 50-100 m). 

 Their growth almost ceases during 

 this penod (Section IIIC3), and their 

 feeding and other activities are prob- 

 ably minimal 



The remaining offshore migra- 

 tion was by an individual which was 

 released about 40 nautical miles (75 

 km) south by east of Martha's Vine- 

 yard in August 1 966, and recaptured 

 off the southern end of the Grand 

 Banks (about 42° 30'N, 71° OO'E) in 

 August 1972 In six years at liberty, 

 its length had increased fi^om 58 cm 

 (estimated age 1), to 180 cm, with a 

 reported weight of 120 kg. This fish 



was approaching "giant" size, and 

 might have been entering the migra- 

 tory pattern proposed for giants ear- 

 lier in this section. 



Tagging has produced no inlbr- 

 mation on the late sprmg migration 

 of small bluefin from this wintering 

 area into the coastal feeding grounds 



In the first half of June 1959, 

 however, an experimental longline 

 fishing operation conducted from the 

 fishing vessel "Golden Eagle", in co- 

 operation with the Bureau of Com- 

 mercial Fisheries (Wilson and Hartlett 

 1967), obtained high catch rales (up 

 10 170 fish per 1,000 hooks) of small 

 (estimated sizes provided by J L 

 Squire, Jr , personal communication) 

 bluefin tuna in the \icinity of latitude 

 39° 20'N, longitude 68° iS'W Since 

 the first appearances of small bluefin 

 in coastal waters in recent years have 

 occurred between the Chesapeake 

 Bay entrance and Long Island 

 (Sakagawa 1975, personal obscr\'a- 

 tions of the authors), their approach 

 to the coast may have been quite simi- 

 lar to that indicated by tag returns for 

 medium bluefin (Figure 80) 



The return to the nurser>' area 

 completes the migratory cycle of the 



young bluefin tuna. Since it appears 

 that few western Atlantic fish in the 

 small size group (ages 1-4) have at- 

 tained sexual maturity, this pattern is 

 not as greatly complicated by spawn- 

 ing activity as is that for small blue- 

 fin in the eastern Atlantic, which evi- 

 dently spawn at younger ages (Sec- 

 tion VIJl) 



The summer and winter habitats 

 of the young bluefin, however, tend 

 to expand with age of fish Age 1 

 bluefin have very rarely been re- 

 corded in the Gulf of Maine, but age 

 2, 3 and 4 fish have occurred in Cape 

 Cod Bay, at the southwestern end of 

 the Gulf, in great numbers in some 

 years Age 3 and 4 fish have been 

 caught in Nova Scotia waters. In win- 

 ter and spring, fish of ages 3 and, 

 especially, 4 have been captured 

 much farther offshore than the win- 

 tering area mentioned above, but usu- 

 ally in small numbers. 



e. Very Small Fish 



Less IS known about the migra- 

 tions of age bluefin in the western 

 Atlantic, since no areas where they 

 concentrate regularly have been 

 found there Hatching occurs exten- 

 sively in the Gulf of Mexico in May 

 and June It also must spread widely 

 over waters adjacent to the Greater 

 Antilles and the Bahamas, and far to 

 the east and north of those islands. 

 The limits of these areas in which 

 bluefin are bom have not been de- 

 fined, but we estimate that they may 

 extend over most of the deep (>200 

 m) waters between latitudes 1 8°N and 

 33°N and between longitude 67°W 

 and the coast and islands Another 

 probable hatching area is north of the 

 Gulf Stream and east of New Jcr.sey 

 and Mar>'land Age bluefin from 

 all these areas must converge by van- 

 ous routes on the nurser>' grounds 

 between Cape Hatteras and Cape Cod, 

 since that is the only western Atlan- 

 tic area in which age 1 bluefin are 

 known to occur regularly en masse. 



The only route by which it seems 

 obvious that such a migration occurs 

 IS from the Gulf of Mexico and adja- 

 cent waters through the Straits of 

 Florida to the northern nursery area 

 The timing of this migration is un- 

 certain 



128 



