Growth, Mortality and Exploitation Rate of Round Sardinella (Sardinella aurita, Valenciennes, 1847) in the New Calabar River, Niger Delta, Nigeria

Abstract

This study assessed the growth, mortality and exploitation rate of Sardinella aurita in the New Calabar River. A total of 513 specimens of S. aurita were collected from artisanal fishers and assessed between March 2020 and February 2021.For statistical analysis, FiSAT II software was used. At asymptotic length (L∞) = 21.73 cm, growth rate (K) = 0.95 yr-1, longevity (Tmax) = 2.68 yrs., theoretical age at birth (t0) = -0.48 yrs., and growth performance index (Φ′) = 2.65. Length at first capture (Lc50 = 15.06 cm) was lower than length at first maturity (Lm50 = 21.12 cm). Mortality parameters revealed a total mortality rate (Z) = 3.03 yr-1, a natural mortality rate (M) = 1.42 yr-1, and a fishing mortality rate (F) = 1.61 yr-1. This indicates that S. aurita in the study area has a fast growth rate, small attained size, delayed sexual maturation, and high natural mortality. The exploitation rate (E) was 0.53. S. aurita was found to be experiencing optimum exploitation. Therefore, to prevent overfishing, sustainable fisheries measures should be adopted, and these include monitoring of fishing efforts and implementation and enforcement of increased mesh size to sustain the fishery of S. aurita in the New Calabar river.

Keywords

• mortality
• growth
• clupeidae
• africa