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Research article - Peer-reviewed, 2009

Predicting site-specific overwintering of juvenile brown trout (Salmo trutta) using a habitat suitability index

Palm, Daniel; Brannas, Eva; Nilsson, Kjell

Abstract

Brown trout (Salmo trutta) site-specific overwintering was studied in an ice-covered stream in northern Sweden. We monitored 238 individually tagged juvenile trout (body length 120-204 mm) from late summer until late winter using portable passive integrated transponder tag equipment and related it to a habitat suitability index. Minimum habitat suitability index explained a large portion (66.8%) of the variation in the proportion of individuals that remained and overwintered at specific sites from late summer until late winter. Our study design detected three scales of overwinter movements: (i) individuals that remained within their tagging site (site-scale movements); (ii) individuals that moved to other reaches (reach-scale movements), which were probably the most common; and (iii) individuals that left the study stream (stream-scale movements). There were no differences in size at tagging among individuals that adopted different scales of movements. We suggest that habitat suitability index can be used as a tool to predict site specific residency and, thus, habitat conditions in stream reaches during winter.

Published in

Canadian Journal of Fisheries and Aquatic Sciences
2009, Volume: 66, number: 4, pages: 540-546