LENARZ ET AL.: YIELD PER RECRUIT OF ATLANTIC YELLOWFIN TUNA 



mortality and less of an increase (perhaps even 

 a decrease) in landed yield per recruit than with 

 the 55-cm (3.2 kg) minimum size and an increase 

 in fishing mortality. 



The results of this paper were obtained using 

 reasonable assumptions and all available data on 

 Atlantic yellowfin tuna. As we increased the 

 number of assumptions we increased the number 

 of conclusions. We think that it is unlikely that 

 use of tecnhiques not used in this paper would 

 result in conclusions that are significantly differ- 

 ent from ours. That is, an increase in effective 

 minimum size would result in a minor increase 

 in yield per recruit, an increase in effort without 

 increasing effective minimum size would not 

 appreciably increase yield per recruit, and an 

 increase in effective minimum size and effort 

 would result in modest gains in yield per re- 

 cruit. We wish to emphasize that these conclu- 

 sions are based on a number of assumptions. 

 We consider the assumptions reasonable, but 

 because they are assumptions any management 

 decisions, including the decision of taking no 

 action, should be followed with careful evaluation 

 of the results. 



ACKNOWLEDGMENTS 



We are indebted to James Joseph and Patrick 

 Tomlinson of the Inter-American Tropical Tuna 

 Commission for their useful comments on this 

 paper. This study would not have been possible 

 without the many valuable contributions of data 

 and ideas by scientists of the nations that parti- 

 cipate in the International Commission for the 

 Conservation of Atlantic Tunas. 



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