Per-Recruit Simulation as a Rapid Assessment Tool for a Multispecies Small-Scale Fishery in Lake Malombe, Malawi, Africa

Per-Recruit Simulation as a Rapid Assessment Tool for a Multispecies Small-Scale Fishery in Lake Malombe, Malawi, Africa

Olaf L.F. Weyl, Anthony J. Booth, Kissa Mwakiyongo, and Moses M. Banda

Per-Recruit Simulation as a Rapid Assessment Tool for a Multispecies Small-Scale Fishery in Lake Malombe, Malawi, AfricaThis is part of Fisheries Assessment and Management in Data-Limited Situations
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Description

The 390 km2 Lake Malombe supports a small-scale fishery that is dominated by the nkacha net, a locally developed purse seine. The nkacha fishery contributes in excess of 95% to the haplochromine cichlid catch from Lake Malombe. Since 1990 the annual haplochromine cichlid yield declined from 9,500 t to less than 4,000 t. In Lake Malombe, as in most African fisheries, the use of assessment methods that allow for dynamic simulation analysis incorporating the response of the stock to changes in management strategy was negated by the lack of directed age based catch data and the lack of information pertaining to the biology of the target species. In this study, a rapid assessment framework for the assessment of biological and fishery input parameters needed for the application of multispecies yield- (YPR) and spawner-biomass per recruit (SBR) analysis is presented. During a one-year assessment period, species selectivity by the nkacha fishery was determined. Length frequency analysis allowed for a first estimate of growth rate for five major target species. These growth rate data were then used to estimate age-selectivity into the fishery, mortality rates, and age-specific maturity for each of the target species. Subsequently, YPR and SBR analyses were used to investigate commonly used "target reference points" as management targets for five target species in the fishery. The results are discussed with reference to the application of per-recruit analysis for the rapid derivation of management advice for multispecies fisheries in data limited situations.

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