■75- 



8) The use of sea surface temperature as an index for 

 partitioning fishing effort on skipjack and yellowfin tuna has been 

 examined. 



9) The economic value of eastern Atlantic tuna fisheries has been 

 assessed. 



IV. C. Future Research Needs 



Proposed future research projects are listed below, together with 

 suggested methods of study and sources of information. 



IV.C.l. Suggested Approach and Methods 



1) Catch/effort data from FISM and Tema-based fleets 

 need to be examined to verify or establish suitable CPUE indices for 

 eastern Atlantic skipjack tuna stock(s). The feasibility of applying these 

 same techniques to catch/effort data for the western Atlantic should then 

 be assessed. 



2) Distribution and migration patterns of Atlantic 

 skipjack stocks need to be examined using tag return results from ISY 

 tagging programs. 



3) Growth and stock structure of eastern and western 

 Atlantic skipjack stocks need to be compared using data to be collected by 

 ISY programs (e.g., length/frequency data for skipjack captured off Brazil, 

 Ascension Island, and in the Gulf of Guinea). 



4) Location, seasonality, intensity, and physiological 

 triggering mechanisms related to skipjack spawning need to be examined. 



5) Preliminary assessments of interactions of small 

 yellowfin, bigeye, and skipjack have been performed. The techniques and 

 data used in these assessments need to be re-examined and preliminary 

 results verified or altered as required. 



6) Environmental data taken during the SWFC skipjack 

 tagging cruise in the Caribbean should be compared with skipjack school 

 sightings to determine if these results agree with published 

 environment/availability relations for other geographic areas. 



7) The identification of skipjack habitat vulnerable to 

 surface fishing gear off Brazil and Argentina (Figure 12) in 1979 preceded 

 the establishment of a substantial fishery in that area in 1980, The 

 seasonal and areal fluctuations of this habitat area need to be examined. 



