O 6 

 O 



o 



X 



cr 



UJ 



4 - 



PRERECRUITMENT EGG PRODUCTION- 



T 



—r— 



1.5 



0.5 1.0 1.5 2.0 



FISHING MORTALITY 



FIGURE 7.— The relationship between fishing mortality and the num- 

 ber of eggs produced per recruit for Macrobrachium faustinum in 

 Cane River. 



effort of shrimp will self-regulate the fishery. The low 

 level of F suggests that this effect is currently 

 operative. 



Even though yield (growth) overfishing is unlikely, 

 the possibility of recruitment overfishing (Cushing 

 1977) must be considered. This too is unlikely, be- 

 cause M. faustinum mature early and a high propor- 

 tion of egg production takes place before recruitment 

 to the fishery (Fig. 7). 



Animals which are small, highly fecund, and mature 

 early are to be expected in a habitat where density- 

 independent mortality prevails and is not stronger 

 and/or more variable for juveniles than for adults 

 (see Stearns 1977). In the rainy season Cane River is 

 subject to flash floods which cause high density- 

 independent mortality of shrimps (Hunte 1976). 

 This is almost certainly true of all high- gradient 

 streams in the Caribbean and the shrimps which in- 

 habit them would be expected to have life history 

 characteristics similar to M. faustinum. It appears 

 likely then that such species, many of which support 

 significant subsistence fisheries, will be resistant to 

 overexploitation and that regulatory management 

 need not be considered. 



Acknowledgments 



This work was supported by an Alcan Junior 

 Research Fellowship and a CIDA/NSERC Research 

 Associateship to W. Hunte. We thank Pat Simpson 

 and Susan Mahon for drafting the figures. 



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