Dynamics of the Fishery for Galjoen Dichistius Capensis, With an Assessment of Monitoring Methods

The dynamics of the fishery for galjoen Dichistius capensis were investigated at four sites in South Africa from 1987 to 2000. At three sites, which were protected from fishing, Koppie Alleen, Lekkerwater (both in the De Hoop Marine Protected Area) and Tsitsikamma National Park, fishery-independent...

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Bibliographic Details
Published in:African journal of marine science 2003-06, Vol.25 (1), p.311-330
Main Author: Attwood, C. G.
Format: Article
Language:English
Subjects:
CPUE
DICHISTIUS CAPENSIS
FISHERY DYNAMICS
Marine
MONITORING METHODS
MORTALITY RATE
SOUTH AFRICA
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Summary:The dynamics of the fishery for galjoen Dichistius capensis were investigated at four sites in South Africa from 1987 to 2000. At three sites, which were protected from fishing, Koppie Alleen, Lekkerwater (both in the De Hoop Marine Protected Area) and Tsitsikamma National Park, fishery-independent surveys were conducted. Data for the Cape Peninsula (the fourth site) were obtained from records kept by a recreational angler. Catch per unit effort (cpue) was highest at De Hoop and lowest at Tsitsikamma. At De Hoop, cpue varied significantly among anglers, months, years and gear type. The mortality rate was greater at the exploited site than at protected sites, where mortality rates were taken as estimates of natural mortality. Tag and recovery data were used to estimate density and catchability. Fishing mortality rates were very high, whether inferred from size distributions or from the product of effort counts and the catchability coefficient. Such high rates can be sustained only through refuges. Variation in fishery parameters among habitats and the high variance in cpue data suggest that an effective monitoring programme will need to be intensive. To provide adequate stock assessments, fishery-dependent surveys should be augmented by studies in marine protected areas.
ISSN:1814-232X
1814-2338
DOI:10.2989/18142320309504020