Abstract
Orthopristis ruber is a species in high demand in Eastern Venezuela, but production has been decreasing in recent years. For this reason, our objective was to estimate the growth and mortality parameters of this resource. Monthly samples were collected from June 2011 to May 2012, obtaining 2980 specimens in El Tirano and Puerto Abajo. Data on total length (cm), total weight (g), and sex were recorded for each specimen. No sexual dimorphism was shown with respect to length (t(S)=1.113, p>0.05), so one length-weight ratio was established for both sexes (Wt=0.0612*Lt(2.54)); and they both exhibited minor allometric growth. Growth was estimated by analysis of length frequency distributions using FiSAT software. The estimated growth parameters (L.=39.03cm, W.=679.60g, k=0.48/year and t(O) = -0.32 year) showed moderately rapid growth. Length frequency data were adjusted to the von Bertalaniffy model, and indicated an exponential tendency of accelerated growth during the first years of life, followed by slow growth until the fish reached its maximum length. The coefficient of variation of the growth index (theta) demonstrated no differences in growth pattern. The natural mortality rate (M=0.97/year), from fishing (F=1.57/year), and total mortality (Z=2.54/year), were high, as well as the exploitation rate (E=0.62/year). We concluded that O. ruber has been fully exploited by artisanal fishers, and suggest a continuous study on population dynamics, to recommend optimum management techniques for the fishery.
Highlights
Los estudios de crecimiento de peces son esenciales para la mayor parte de los objetivos de la evaluación pesquera, tanto en las regiones tropicales como en las templadas, debido a que el crecimiento individual de los organismos constituye, a través del tiempo, la fuente de suministro de las capturas extraídas por una pesquería (Pauly, 1983)
Para determinar la existencia de diferencias significativas entre los coeficientes de machos y hembras, se aplicó la hipótesis del crecimiento isométrico (Ricker, 1975) mediante una prueba ts
Se concluye que O. ruber no evidencia dimorfismo sexual con respecto a la longitud y presenta un crecimiento moderadamente rápido con una alta tasa de explotación lo cual demuestra que el recurso está plenamente explotado por la pesca artesanal; por lo que se sugiere continuar con los estudios de dinámica de poblaciones para evaluar la pesquería con fines de manejo
Summary
Los estudios de crecimiento de peces son esenciales para la mayor parte de los objetivos de la evaluación pesquera, tanto en las regiones tropicales como en las templadas, debido a que el crecimiento individual de los organismos constituye, a través del tiempo, la fuente de suministro de las capturas extraídas por una pesquería (Pauly, 1983). Los parámetros de crecimiento estimados de O. ruber, fueron comparados con resultados obtenidos por otros investigadores en diferentes regiones, mediante el índice phi prima (Ø’) de Munro y Pauly (1983): Ø’=Log10k+2Log10L∞ y el criterio de Sparre y Venema (1997), quienes establecen que el coeficiente de variación (CV) no debe exceder del 4% para poder asumir que los resultados son estadísticamente similares.
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