FISHERY BULLETIN: VOL. 87, NO. 8. 1989 



Station 631 and 632 (Table 2). Station 727 was 

 located at a shallower isobath than station 728 

 and the temperature at depth readings were 

 similar to those 800 km south, at stations 632 and 

 631, where the water depth was similar. At both 

 pairs of stations cold water is nearer the surface 

 of the inshore station. The sloping isotherms and 

 the temperatures at depth are characteristic of 

 the edge of the Gulf Stream. Gulf Stream water 

 is expected here in spring and summer (Pietra- 

 fesa et al. 1985). 



Remote sensing observations (Figs. 6, 7) show 

 that remnants of a filament of warm water re- 

 sulting from an earlier onshore meander were 

 still present when these larvae were collected. 

 Upwelling is associated with onshore meanders 

 of the Gulf Stream and cyclonic eddies are 

 formed between the warm filament and the Gulf 

 Stream. The bluefin tuna larvae at stations 727 

 and 728 were not over the shelf in a patch of 



Table 2. — Temperature with depth comparison of north- 

 ern stations where bluefin larvae were present and south- 

 ern stations which were at the same isobath and in Gulf 

 Stream water. Bluefin were collected at stations 727 and 

 728. Stations 728 and 631 were offshore (Fig. 1.). Note 

 that 22° at 100 m is a good indicator of the Loop Current 

 (Liepper 1 970) which flows from the Gulf of Mexico to join 

 the Gulf Stream. 



Temperature (°C) 



Northern stations 



Southern stations 



productive water caused by the onshore mean- 

 der, but they were in an area which could have 

 been fertilized by such a patch which subse- 



FiGURE 6. — Chart showing the position of the edge of the 

 Gulf Stream on 13 May 1985 relative to two stations (727 and 

 728) where bluefin larvae were collected 14 May. Note the 

 three filaments left by meanders of the Stream. These can 

 enclose cold cyclonic eddies. (Redrawn from NOAA Gulf 

 Stream System Flow Chart #2450, 13 May 1985.) 



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