New Zealand Journal of Marine and Freshwater Research abstracts

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Social interactions between 0+ brown and rainbow trout in experimental stream troughs

JOHN W.HAYES*

Department of Zoology University of Canterbury Private Bag Christchurch 1, New Zealand

*Present address: Fisheries Research Centre, Ministry of Agriculture & Fisheries, P.O. Box 6016, Rotorua, New Zealand

Abstract Social interactions between 0+ brown trout (Salmo trutta L.) and rainbow trout (S. gairdneri Richardson) were examined in a pair of stream observation troughs. The two species exhibited similar agonistic behaviour and interacted socially. As fry (< 3 5 mm), rainbow trout were dominant over brown trout in the shallow, faster water (< 15 cm deep, < 15 cm s"¹) nearest the incoming food supply. In fingerlings (c. 43-67 mm), social status was reversed throughout the troughs with brown trout dominant over rainbow trout. A size ratio of 1.7 between early-emerged brown and rainbow fingerlings and late-emerged rainbow fry reduced aggression between these fish. Prior residence had only a minorpositive influence on social dominance.

Keywords brown trout; rainbow trout; social interaction; aggression; segregation; competition; prior residence; Pisces; Salmonidae; Salmo trutta; Salmo gairdneri; Oncorhynchus mykiss

New Zealand Journal of Marine and Freshwater Research, 1989, Vol. 23: 163-170 0028-8330/2302-0163S2.50/0 © Crown copyright 1989 Received 31 May 1988; accepted 9 August 1988

PDF file of entire paper: medium quality (665K); (scanned from paper original: notes about this process)

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