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Introduction and extinction of brown trout (Salmo trutta L.) in an impoverished subantarctic stream

Published online by Cambridge University Press:  13 May 2004

J. Cooper
Affiliation:
Percy FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch 7700, South Africa
J.E. Crafford
Affiliation:
Department of Entomology, University of Pretoria, Pretoria 0002, South Africa. Department of Zoology, University of Venda, Pvt Bag X2220, Sibasa, Venda, southern Africa
T. Hecht
Affiliation:
Department of Ichthyology and Fisheries Science, Rhodes University, P O Box 94, Grahamstown 6140, South Africa

Abstract

Brown trout were introduced to the Van den Boogaard River on subantarctic Marion Island in 1964, and a small population became established. The last individual was seen in 1984, and the species is now considered to be extinct on the island. Their diet was exclusively allochthonous, with snails and spiders predominating. Ages estimated at six to eleven years showed that spawning must have occurred since the original introduction. Since the Van den Boogaard River enters the sea via a waterfall, it is postulated that trout were not able to practice an anadromous life-style, and that this, as well as other factors connected with the impoverished nature of the stream, led to dwarfing of the resident population. No further introductions of alien fish to Marion Island should be contemplated.

Type
Papers—Life Sciences and Oceanography
Copyright
© Antarctic Science Ltd 1992

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