Length-based growth, mortality, and biological reference points of Chrysichthys nigrodigitatus (Lacepède, 1803) from the Yeji arm of Lake Volta, Ghana

Abstract

Individuals of Chrysichthys nigrodigitatus from Lake Volta, Ghana (West Africa), were examined between January and December 2020 for growth, mortality, and exploitation rate using total length measurement. Monthly length-frequency data were collected from 244 samples and analysed using the FiSAT II Tool. The estimated asymptotic total length (L∞), the coefficient of growth (K), and the calculated growth performance index (phi) were 27.3 cm, 0.57, and 2.63 pear year, respectively. The total mortality rate (Z), natural mortality rate (M), and fishing mortality rate (F) were 1.57, 0.92, and 0.66 pear year, respectively. The exploitation rate (E = 0.42) was below the optimum level of 0.5, which indicates that the species is underexploited. Based on the Emsy (0.56) value, analyses show that the exploitation rate is below the sustainable limit, hence the need for continuous monitoring of fishing efforts to ensure that the limit reference point is not exceeded.