The Cichlid Fishes of Lake Malawi, Africa

Abstract of Publication

Booth, A.J. 2001. Determination of biological reference points for Lake Malawi cichlids. Pp. 248-259 in: Weyl, O.L.F., and M.V. Weyl (Eds). Proceedings of the Lake Malawi Fisheries Management Symposium, 4th-9th June 2001, Capital Hotel, Lilongwe. National Aquatic Resource Management Programme (NARMAP), Monkey Bay. 272 pp.  

Biological reference points (BRPs) - values that represent the state of a fishery or population - are commonly used to guide management decisions. BRPs are expressed as a function of fishing mortality and are derived from models that describe the population dynamics of a resource. These models include dynamic pool, spawner-recruit and production models. Unfortunately, in the absence of long-term fisheries data, such as abundance indices and catches-at-age, it is only dynamic pool models, usually known as yield-per-recruit and spawner biomass-per-recruit models, that are known with any degree of certainty. BRPs that have been proposed in the literature have been calculated for temperate demersal marine species with life-history characteristics that include high fecundity, pelagic spawning and little or no parental care. In contrast, cichlids have low fecundities and exhibit varying levels of parental care ranging from guarding to mouthbrooding. Cichlid specific BRPs, calculated with combinations of two spawner-recruit relationships within deterministic and stochastic frameworks, were shown to be highly dependent on the degree of density-dependence in the spawner-recruit relationship. Overall, cichlid specific BRPs were similar to than [sic] temperate groundfish species and it is suggested that fishing mortality be maintained at no more than that required to reduce spawner biomass-per-recruit to 40% of pristine levels if the form of the spawner-recruit relationship is unknown. If a Beverton-Holt spanwer-recruit relationship is assumed, a biologically plausible relationship given cichlid life-histories, then it is suggested that spawner biomass-per-recruit is not reduced below 50% of unfished levels.




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