Mortality and growth of the rock oyster, Crassostrea iridescens (Hanley, 1854), at San Ignacio, Sinaloa, Mexico

Abstract

With the aim of contributing with technical information necessary for the management of the rock oyster fishery in Sinaloa (Mexico), a survey of the rock oyster Crassostrea iridescens was done using individual buoys hooked to the rocky bottom in order to recover and identify 99 tagged specimens, including estimates for natural mortality (M), growth rates and the relationship between total length and total weight. Data for rock oysters were recorded during two sampling phases (March-April and September-October 1995), and in both cases survival rates (S) were near 80% to give a final estimation of M = 2.2y^–1. The lengthweight relation indicates a negative allometric growth, with coefficient values significantly smaller than 3.0 for each period (2.18 and 2.61). The values for the growth parameters of the von Bertalanffy model were L_∞ = 134 mm and 155 mm, K = 0.069 and 0.098, t₀ = –0.66 and –0.40 for each period. The results agree with the annual environmental variations present in the study area, and appear sufficiently reliable for use in the management of the rock oyster.