UBC Faculty Research and Publications

Belated Contributions on the Biology of Fish, Fisheries and Features of Their Ecosystems Pauly, D. (Daniel); Hood, Lincoln; Stergiou, Konstantinos I.

Abstract

Age and growth of Mediterranean slimehead, Hoplostethus mediterraneus in the Ionian Sea, Greece, were studied and morphometric relationships of otolith morphological characteristics were established, based on samples collected in 1996-1997. The length-weight relationships were positively allometric (sexes separately and combined). A strong correlation was found between total length (TL) and otolith weight, with the morphological characteristics of the otoliths (i.e., length, diameter, width and perimeter). The maximum age recorded, based on otolith reading, was nine years, for a female individual of TL of 22.2 cm, while males reached a maximum age of six years (TL=19.9 cm). Five different growth models were compared: the von Bertalanffy growth function (VBGF), the generalized VBGF, the Gompertz model, the logistic model, and a power model. The VBGM and Gompertz had substantial support by the data of female growth, while Gompertz and the logistic model were substantially supported for the growth of males. With the combined sexes, three models had substantial support: VBGF, generalized VBGF, and Gompertz. The model-averaged asymptotic length of H. mediterraneus was estimated (point estimate and 95% confidence interval in parentheses): 22.5 cm (20.9 – 24.0), 22.0 cm (16.0 – 28.1) and 23.6 cm (21.4 – 25.8), for females, males, and combined sexes respectively. The estimated parameters of the von Bertalanffy equation for both sexes combined were: L∞=23.9 cm, K = 0.242 year-¹, and t₀= -1.39 years, whereas for the two sexes separately were estimated as: L∞=24.2 cm, K= 0.241 year-¹, t₀= -1.32 years, and L∞=23.2 cm, K= 0.244 year-¹, t₀= -1.52 years, for females and males respectively.

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