Management advice for the Diplotaxodon limnothrissa (Teleostei: Cichlidae) resource in the south-east arm of Lake Malawi, based on per-recruit analysis.

摘要

Diplotaxodon limnothrissa is a widely distributed species occurring throughout Lake Malawi (Malawi) and is probably the most abundant cichlid in the pelagic zone of the lake. The species is exploited commercially in the southeast arm of the lake, but since the fishery's inception the resource has never been assessed. Stock assessment of D. limnothrissa resource in stern-trawl and pair trawl fisheries in the southeast arm of Lake Malawi was performed based on per-recruit analysis, with growth, maturity, mortality and age of fish as input parameters. The age-specific selectivity for the stern-trawl and pair-trawl fisheries was estimated based on data collected in 1999 and 2001, respectively. The results showed that the age at which 50% selectivity occurs was estimated to be 2.67 and 1.93 years for the stern-trawl and pair-trawl fisheries, respectively, which corresponded to total length of 146 and 109 mm. Significant differences for both length and age at selection were observed between the 2 fisheries. Per-recruit analysis indicated that the resource was underexploited, with current spawner biomass per-recruit between 55 and 74% of pristine levels..