Aspects of the population biology ofCephalopholis fulvafrom the central coast of Brazil

Abstract

Summary Age and size composition samples of Cephalopholis fulva from the central coast of Brazil were collected from research surveys and from line fishery landings between 1997 and 1999. The samples suggest that the submarine banks located further offshore are characterized by having fish larger than those caught in the continental shelf area. Although the oldest specimens were caught in the continental shelf area, only 34.6% of the specimens were older than 10 years as compared to 51.4% in the submarine banks. The observed size and age differences seem to be related to the lower fishing pressure on the submarine banks, although size composition bias resulting from different sampling procedures and different catchability between sites cannot be excluded. A resampling scheme was used to overcome the influences of size composition bias and to generate a three-dimensional plot of parameters as a means to compare the growth between the submarine banks and the continental shelf area; this plot showed no overlap between growth patterns of the two sites. The natural mortality (M) estimate based on the oldest specimen observed was 0.17 year−1. Total mortality (Z) estimated from catch-curve analyses using samples from both areas varied from 0.24 to 0.34 year−1, depending on the age range used. With this level of mortality, the C. fulva stock in the central coast area of Brazil was close to or already at the level of overexploitation in the late 1990s.