(NOV. 21) 70^ 



28" 

 N. 



27" 



CRUISE TO -66-1 

 NOVEMBER 1966 



PART 1 (NOV. 4 - 18) 

 PART 2 (NOV. 18-21) 

 NOON STATIONS 

 MIDNIGHT STATIONS 

 OTHER STATIONS 



68 (NOV. 18) 



116°W 



115° 114° 113° 112° 111° 



FiQUEE 13. — Track and station position.s for crui.se TO-66-1. 



110" 



26° 



1 25° 



24° 



23° 



22° 



109° 



becomes rather uniform in areas of suitable tem- 

 perature, and finally the physical environment 

 again becomes unsuitable with the start of winter 

 cooling. The supply of pelagic red crabs remains 

 fairly high throughout the year (Longhuret, 1967; 

 Blackburn, 1968; and this paper). 



The foregoing interpretation of the tuna dis- 

 tribution data might be criticized on two grounds. 

 One is that nearly all the tuna catches shown in 

 the charts were within 100 nautical miles (185 

 km.) of the coast, although suitable environmental 

 conditions occurred much farther offshore on some 



of the cruises (see figs. 8 and 10), as well as in the 

 inshore areas where the catches were made. Charts 

 of lATTC data from the commercial fishery for 

 many years, compiled by Joseph and Calkins 

 ( 1969) , show clearly that most of the fishing effort 

 in the Baja California area is expended and most 

 of the catch of both species taken within about 

 100 nautical miles of the coast. This situation is 

 understandable because the tuna are associated 

 with upwelling, which is a coastal process, and 

 fishermen generally do not operate farther off- 

 shore than is necessary to make good catches. On 



DISTRIBUTION OF TROPICAL TUNAS OFF WESTERN BAJA CALIFORNIA 



171 



