Antarctic Science


Antarctic Science – Special Issue
Papers—Life Sciences and Oceanography

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


J. Cooper a1, J.E. Crafford a2p1 and T. Hecht a3
a1 Percy FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch 7700, South Africa
a2 Department of Entomology, University of Pretoria, Pretoria 0002, South Africa.
a3 Department of Ichthyology and Fisheries Science, Rhodes University, P O Box 94, Grahamstown 6140, South Africa

Article author query
cooper j   [PubMed][Google Scholar] 
crafford j   [PubMed][Google Scholar] 
hecht t   [PubMed][Google Scholar] 

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.

(Received August 8 1990)
(Accepted June 3 1991)


Key Words: anadromy; diet; fish; growth; life-history style; Marion Island.

Correspondence:
p1 Department of Zoology, University of Venda, Pvt Bag X2220, Sibasa, Venda, southern Africa


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