HUNTSMAN ET AL.: YIELD PER RECRUIT MODELS 



Vermilion Snapper M=0.40 



Yield Per Recruit in Weight 



Z 



UJ 



s 



3 

 oc 

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needed to take the maximum. At the highest 

 estimates of M, 73, 60, 83, and 90% of maximum 

 yield can be taken with an F of 0.3, which is 55, 1 7, 38, 

 and 33%, respectively, of the effort needed for maxi- 

 mum yield. 



For less numerous, larger species, conservative har- 

 vest strategies would be even more successful than 

 for smaller fishes. For instance, for speckled hind, 

 snowy grouper, scamp, and for gag and red snapper at 

 their lowest M estimates, 94, 95, 89, 94, and 78% of 

 the maximal yield per recruit can be taken if F= 0.3 

 which is 60, 79, 42, 14, and 60% of the F required to 

 take that maximum. Even at the high estimate of M 

 for gag and red snapper, 78 and 88% of the maximal 

 yield perrecruitare available if F= 0.3. This F is only 

 9 and 42% of that needed to take the maximum. 



While the absolute relationship of recruitment age 

 to yield varies according to species, it is true for all 

 species that the lower the fishing mortality, the 

 greater the range of recruitment ages at which the 

 highest available yield may be taken At F = 0.3, re- 

 cruitment age, regardless of M, could range over 4 or 

 more years for 9 of the 1 8 models without substantial 

 loss of yield; for the remaining models it could range 

 over 3 yr. 



FIGURE 4.— Yield per recruit in 

 weight of vermilion snapper 

 where M = 0.40. 



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FIGURE 5. — Yield per recruit in weight 

 of vermilion snapper where M = 0.25. 



z 



UJ 



2 



5 



at 



*Z 4 



Vermilion Snapper M = 0.25 



Yield Per Recruit in Weight 



200g 



250g 



0.1 02 03 04 05 06 0.7 08 09 10 



685 



