Sex ratio, gonad maturity and size-structure of Pagelus bellotti in Sierra Leone

Abstract

A total of 135 specimens of Pagellus bellotti were randomly collected from artisanal boats in August 2018. Study of sex ratio, gonad maturity and size-structure of Pagellus bellottii is meagre in Sierra Leone, and forms the basis of the present study. The study will contribute to current knowledge and promote rational exploitation of the stock. Length and weight were measured using a fish measuring board (cm) and digital weight scale (g) respectively. Sex and gonad maturity were macroscopically assessed. Results showed dominant males (71.9%) and significant difference observed (1:2.6) and expected (1:1) female: male sex ratios (p <0.05). Only 11.9% and 11.1% of male and female gonads transcended to the developed stage (Stage IV). The length-frequency distribution for combined sex was unimodal (modal class, 17cm-20.9cm). Mean length and weight respectively were, 19.04±0.32cm and 98.85±5.08g for males and 17.43±0.54cm and 78.61±6.32g for females. Growth exponent (b) for male, female and combined sex was 2.809, 2.928 and 2.850 respectively and the correlation coefficient for all sex categories showed (r > 0.9). Indexes of condition were greater than 1.0 (K > 1) for all sex categories. Results portrayed a heterogeneous gender population of Pagelus bellottii and vast similarity in reproductive strategies by both sexes. The fish comprised of one size group and males may be growing larger than the females. Growth pattern was near-isometric for females and negative allometric for the males, and both sexes were in better condition (K >1.0). An annual study could provide further insight.