New Zealand Journal of Marine and Freshwater Research abstracts
Natal-stream rearing in three populations of rainbow trout in Lake Taupo, New Zealand
MARVIN L.ROSENAU
Department of Biological Sciences
University of Waikato
Private Bag, Hamilton, New Zealand
Abstract
Scales were taken from adult rainbow trout
(Oncorhynchus mykiss, previously
Salmo gairdneri) from the Waimarino, Tokaanu, and Hinemaiaia Rivers; these are tributaries of Lake Taupo, New Zealand. The scales showed both widely-spaced outer, and narrowly-spaced inner, circulus zones. Although there were no among-population differences in average circulus spacing in the outer growth zone, there were significant among-population differences in the inner zone; these two zones are suggested to represent (common) lake and natal-stream rearing, respectively. The back-calculated minimum and average lengths at migration of juveniles from stream to lake was similar for all three populations (c. 94 mm and 140 mm, respectively) but there were significant among-population differences in age at emigration. The scale patterns and stream sampling suggested that most Hinemaiaia River rainbow trout left the river within the first year whereas much higher proportions of juveniles in the other two streams overwintered before emigrating in their second year.
Keywords Oncorhynchus myldss; Salmo gairdneri; rainbow trout; juvenile; migration; natal-stream rearing; scale patterns; circuli
New Zealand Journal of Marine and Freshwater Research, 1991, Vol. 25: 81-91 0028-8330/2501-0081 $2.50/0 © Crown copyright 1991
Received 12 March 1990; accepted 23 January 1991
PDF file of entire paper: medium quality (1181K); (scanned from paper original: notes about this process)
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