Abstract

We used a matrix population model to analyze the effeet of fishing mortatity on the dynamics, structure and tife history traits of the red hind population in western Puerto Rico (PR). The tife cycle of the red hind was divided into four stages: (1) eggs-Iarvae-juveniles, (2) small, (3) medium, and (4) large females. We assumed the population to be close (Le. no larval input ffOm other stocks), or open, and used published data to parameterize the model. The analysis indicated a population growth rate (8=Nt+l/N¡) of 0.622 for a close population under the current fishing pressure. The analysis also points towards a significant reduction in the relative abundance of large females. Elasticity analysis of the tife cycle transitions (Le. their proportional effeet on 8) indicates that the most important transitions are the survivorships, specifically that of medium females, while the least important are the fecundities. Analysis assuming an open population suggests that recruits from other populations equivalent to 20% of the contribution made by local females would result in the local population stabilizing at a size 90% smaller than its pre-exploitation size.\This result is consistent with the actual behavior of the PR population. If, as this analysis suggests, the PR population,is reeeiving an outside contribution of recruits equivalent to 20% of the contribution made by local females, fishing mortality would need to be reduced from the current 0.31 to 0.02 for the local population to attain its original size. We conclude that the red hind population in western PR is a "sink" (i.e. 8<1), and that recruitment from other stocks is keeping it at a relatively small but stable size.

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