New Zealand Journal of Marine and Freshwater Research abstracts

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Movement of rainbow trout (Oncorhynchus mykiss) during the spawning migration in the Tongariro River, New Zealand

M. DEDUAL

Department of Conservation
Private Bag
Turangi, New Zealand

I. G. JOWETT

National Institute of Water & Atmospheric
 Research Ltd
P. O. Box 11 115
Hamilton, New Zealand

Abstract  The movements of 74 rainbow trout (Oncorhynchus mykiss) were monitored every 2-3 days using radio-telemetry during the spawning migration up the Tongariro River, New Zealand, between June and November 1995. Contrary to the views of anglers, movements of individual fish were highly variable and upstream movement could not be predicted from environmental conditions and fish related variables (length, sex, and reproductive status). There was no significant difference in individual movement between male and female fish. When individual movements were in an upstream direction, maiden trout moved faster, but less often, than fish that had spawned in previous years. The flow in the lower river explained 9% of the variance in individual downstream movements. Net upstream movement occurred throughout most of the study period with above mean activity when the river was in spate, especially early in the migration season when fish responded to flow changes as low as 7%. Above mean upstream daily movement occurred 8 times on rising and 9 times on falling barometric pressure. Large floods caused downstream displacements, but fish tended to move up stream again on the flow recession. The most noticeable downstream movement occurred following the eruption of Mount Ruapehu.

Keywords  rainbow trout; spawning migration; fish movement; flow regime; volcanic eruption; radio-telemetry

M98016
Received 23 April 1998; accepted 18 November 1998

PDF file of entire paper: medium quality (1161K); (scanned from paper original: notes about this process)

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