Short Communication

Juvenile population dynamics of Oreochromis mossambicus in an intermittently open estuary at the limit of its natural distribution

Published in: African Zoology
Volume 43, issue 2, 2008, pages: 277–283
DOI: 10.1080/15627020.2008.11657245
Author(s): B.R. EllenderDepartment of Ichthyology and Fisheries Science, South Africa, O.L.F. WeylDepartment of Ichthyology and Fisheries Science, South Africa, M.K. ShanyengangeDepartment of Ichthyology and Fisheries Science, South Africa, P.D. CowleySouth African Institute of Aquatic Biodiversity, South Africa

Abstract

Juvenile Oreochromis mossambicus in the 25 ha, temperate, intermittently open, East Kleinemonde Estuary in the Eastern Cape, South Africa (33°32’S, 27°03’E), showed a seasonal shift in distribution, occupying all areas of the estuary in summer and, subsequently, being limited to the upper reaches in winter. The young of the year in the littoral zone were rapidly depleted and resultant estimates of the instantaneous rate of total mortality (Z) ranged from 5.4/yr to 6.9/yr. High annual rates of juvenile mortality and small adult populations imply that stock recovery after a reduction in adult population numbers, through activities such as fishing, may be slow. This work adds to the knowledge base of O. mossambicus ecology and population dynamics in temperate estuaries at the limit of its natural distribution

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