AHRENHOLZ ET AL : ATLANTIC MENHADEN POPULATION AND FISHERY 



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F-MULTIPLE 



Figure 18. — Hypersurface representation of potential yield per recruit 

 for Atlantic menhaden with varied age of recruitment and fishing mortal- 

 ity for conditions extant during 1970-72. The X denotes estimate of actual 

 yield per recruit for the time period. 



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F-MULTIPLE 



Figure 19. — Hypersurface representation of potential yield per re- 

 cruit for Atlantic menhaden with varied age of recruitment and fish- 

 ing mortality for fishing conditions extant during 1976-78. The X 

 denotes estimate of actual yield per recruit for the time period. 



Results from these analyses indicate a general 

 reduction in the maximum potential as well as 

 actual yield per recruit from the early to the late 

 1970's, but the maximum potential total yield is 

 greater in the later time period due to increased 



numbers of recruits (Table 10). Thus, estimation 

 of potential changes in yield by the Atlantic men- 

 haden fishery from yield-per-recruit models be- 

 comes a function of density-dependent growth 

 rates (lower yield per recruit with larger year 



591 



