Age, growth and yield-per-recruit analysis of ndunduma Diplotaxodon limnothrissa (Teleostei: Cichlidae), in the southeastern arm of Lake Malawi
Analysis of sectioned sagittal otoliths revealed that D. limnothrissa is fast growing and relatively long-lived species, attaining ages in excess of 10 years. Growth in length was rapid in immature fish, with fish attaining almost half of their maximum size within their first year. Length-at-age was described by the von Bertalanffy growth model with combined-sex growth described as L_t_ = 211.21(1-exp(-0.24(t+1.36))) mm TL. Total, natural and fishing mortalities were estimated at 0.76 yr^(-1), 0.31 yr^(-1) and 0.45 yr^(-1) respectively.
Per-recruit analysis indicated that the D. limnothrissa stock in the southeast arm of the lake is fully exploited as indicated by the current spawner biomass-per-recruit ratios of 31-55% (SB/R)_F=0_. Modelling indicated that the current age-at-capture (2.67 years) is lower than the age at which yield is optimised (> 5 years) based on the F_0.1_ harvesting strategy. It is, therefore, recommended that the age-at-capture should be increased from 2.67 to 5 years to optimise yield.
School Location:South Africa
Source Type:Master's Thesis
Keywords:ichthyology fisheries science
Date of Publication:01/01/2004