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IV. STATUS OF CURRENT RESEARCH NEEDS AND EFFORTS 

 IV. A. Major Research Problems 



Population assessments for all three species were based on 

 incomplete catch and effort data. Better assessments are needed, 

 particularly of the black marl in. Yield-per-recruit and cohort analyses 

 would contribute more definitive assessments of the populations. For these 

 analyses, size-at-age relationships need to be confirmed for blue and 

 striped marl ins and need to be obtained for black marl in. Also needed are 

 estimates of population parameters, e.g., natural and fishing mortality 

 rates, recruitment rates, etc. 



Another problem related to population assessment is the lack of 

 knowledge of the stock structures of these species, although it may be 

 possible to circumvent the need for precise stock identification. The 

 Bill fish Stock Assessment Workshop (Shomura 1980) recommended the use of 

 simulation studies to evaluate the sensitivity of stock assessments to 

 various stock structure hypotheses on the striped marl in so that the need 

 for a stock identification program might be determined. Should such 

 studies prove to be effective for striped marl in, they should be considered 

 for the blue marl in and black marl in as well. 



IV. B. Current Research Efforts 



The first attempts to assess the status of blue marl in, striped 

 marl in, and black marl in stocks were described in background papers 

 submitted to the Bill fish Stock Assessment Workshop (Shomura 1980). The 

 need for further research on the billfishes was stressed at the workshop 

 but, aside from routine data collecting efforts, no real effort is being 

 expended to update the stock production analyses or carry out other 

 analyses suggested at the workshop. 



IV. C. Future Research Needs 



Detailed data on growth, mortality, reproductive rates, and other 

 vital determinants of population dynamics which are required for a complete 

 understanding of the effects of fishing on stock productivity and catch, 

 are not available for Pacific billfishes such as the blue marlin, black 

 marl in and striped marlin. Limited data on size composition and growth 

 rates are available, as well as some statistics on nominal fishing effort 

 and catch. These permit only tentative assessment of the stocks. Effort 

 is therefore needed to upgrade these assessments and to define better the 

 stock structure of the marlin species in the Pacific. 



