ABRAMSON and TOMLINSON: APPLICATION OF YIELD MODELS 



tioning as females were made available from 

 unpublished sources, but a good method for pre- 

 dicting the fraction of age I shrimp that would 

 function as females was not found. Thus^ a 

 simple mean was computed from the data avail- 

 able for years 1957 through 1967 (Table 8) . It 

 is assumed that this mean proportion (0.33) pre- 

 dicts the fraction of the biomass of age I shrimp 

 alive in September that will be females and that 

 the sum of the September biomass of ages II and 



III, plus the fraction of age I functioning as fe- 

 males in September, is directly proportional to 

 spawning biomass during the spawning season. 

 Recruitment was defined as the number of 

 age I shrimp alive on May 1 of each year. Thus, 

 the female biomass in September of season i is 

 proportional to the biomass which will spawn 

 sometime prior to May of season i+1 and the 

 progeny of this spawning will be recruited to the 

 fishery at the beginning of season i + 2. Two 



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