Legends for M. Blackburn's Figures 



Fig. 1. Distribution of tropical tuna and environmental properties off 

 Baja California: the situation early in the tuna season, when 

 tongues of biologically rich upwelled waters are too cold for 

 the tunas except at the edges. 



Fig. 2. Distribution of tropical tuna and environmental properties off 

 Baja California: the situation later in the tuna season, when 

 tongues of biologically rich upwelled waters are warm enough for 

 tunas to penetrate. 



Fig. 3- Distribution of tropical tuna and environmental properties off 

 Baja California: a later situation, like Fig. 2 except that 

 the tongue of biologically rich upwelled water is not shown by 

 the temperature . 



Fig. 4. Distribution of tropical tuna and environmental properties off 

 Baja California: the situation late in the tuna season when 

 no signs of upwelling remain. 



Fig. 5. Skipjack tuna forage on EASTROPAC Expedition, August- September 



1967, in ml. /l, 000 m3: (Above) as observed in net hauls; 

 (Below) as estimated from a regression on surface chlorophyll. 



Fig. 6. Skipjack tuna forage on EASTROPAC Expedition, February-March 



1968, in ml. /l, 000 ml: (Above) as observed in net hauls; 

 (Below) as estimated from a regression on surface chlorophyll. 



3-5 



