Growth, Maturity, And Size-At-Age Variation Of The Bigheaded Shrimp Heterocarpus Vicarius (Decapoda, Pandalidae) In The Eastern Tropical Pacific Off Colombia

The bigheaded shrimp, Heterocarpus vicarius, is a commercially important species fished by bottom-trawling fleets in the Colombian Pacific. However, the life-history parameters necessary for a proper analysis of the population dynamics of this species remain unknown. This paper studies the growth, maturity, and size-at-age variations, of Heterocarpus vicarious, as well as observations on recruitment patterns. The Von Bertalanffy growth parameters were estimated by sex through modal progression analysis, which consisted of grouping cohorts into age classes. Growth parameters were similar for males and females, without significant differences (F = 3.23, p > 0.05). The growth of both sexes is described by the following parameters: L-infinity = 15.26 +/- 1.93 cm total length (TL), K = 0.594 +/- 0.24 yr(-1), and t(0) = 0.66 +/- 0.31 yr. Size-at-age variability was due mainly to processes occurring before larval settlement, since the mean length of same-age individuals born during different reproductive events (intercohort) varied more than that of individuals born during the same reproductive event (intracohort). Length at 50% maturity was estimated at 11.72 cm TL for females, with 95% confidence intervals between 10.57 and 13.71 cm TL. The growth curve and the relatively advanced age at maturity estimated for H. vicarius in the study area suggest the species is very vulnerable to fishing exploitation.