Growth, mortality and exploitation rate of goete, Cynoscion jamaicensis (Perciformes: Sciaenidae), in Southeast Brazil coast

Abstract

Length frequency analysis were applied for Cynoscion jamaicensis (Jamaica weakfish) data collected from commercial catches throughout Southeastern Brazilian coast (24° - 29°S), in order to evaluate growth parameters, instantaneous mortality coefficients and exploitation rates. The growth parameters were estimated by the von Bertalanffy growth equation, using length data at two years groups: 01/1993 í  03/1995 and 04/1997 í  04/1998. Growth mean parameters for the two groups of years were estimated as: L∞ = 39.0 cm, K = 0.40/year, to = -0.38 and í" â€™ = 2.78 (for the period 1993/1995); L∞ = 40.0 cm, K = 0.41/year, to = -0.35 and í" â€™ = 2.82 (for the period 1997/1998). Instantaneous total mortality coefficients (Z) per year group were estimated using catch curves and empirical formulas. Instantaneous natural mortality coefficients (M) were estimated using the PAULY’s empirical equation (PAULY, 1980) and RIKHTER and EFANOV (1976) empirical equation. Instantaneous fishing mortality coefficient (F) and exploitation rate (E) increased 24% and 11%, respectively for the 1993/1995 and 1997/1998 periods. These results were corroborated by an increase in the landed production (kg) in the last years. At last, suggestions for the management of the fishing activity are done.