Seasonal and spatial variation in the diet of brown trout (Salmo trutta L.) in the subarctic River Laxá, north-east Iceland

This study examines seasonal and spatial patterns in the diet composition, stomach fullness and condition of a landlocked population of brown trout (2.5-61.3 cm) in the lake-fed River Laxá in NE-Iceland. The stomach contents consisted predominantly of benthic invertebrates, such as blackfly larvae S...

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Bibliographic Details
Published in:Aquatic ecology 2004-01, Vol.38 (2), p.263-270
Main Authors: Gislason, G M, Steingrimsson, SO
Format: Article
Language:English
Subjects:
Benthic fauna
Fish
Fluctuations
Freshwater
Lakes
Larvae
Outlets
Predation
Radix peregra
Rivers
Salmo trutta
Sharks
Simulium vittatum
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Summary:This study examines seasonal and spatial patterns in the diet composition, stomach fullness and condition of a landlocked population of brown trout (2.5-61.3 cm) in the lake-fed River Laxá in NE-Iceland. The stomach contents consisted predominantly of benthic invertebrates, such as blackfly larvae Simulium vittatum (58%), chironomids (24%) and the freshwater snail Radix peregra (7%). The seasonal and spatial patterns of S. vittatum in the stomach contents were consistent with published studies on the life cycle and production of S. vittatum in the River Laxá. Close to the Lake Myvatn outlet (0-16 km), S. vittatum constituted 63% of the stomach content volume, and exhibited two peaks (i.e., generations) in its seasonal contribution to the stomach contents, whereas further downstream (16-35 km) S. vittatum constituted 45% of the volume and showed only clear evidence of one generation. Seasonal fluctuations in S. vittatum availability appear to affect the stomach fullness and the condition factor of the trout, especially close to the lake outlet where the fluctuations are pronounced.[PUBLICATION ABSTRACT]
ISSN:1386-2588
1573-5125
DOI:10.1023/B:AECO.0000032052.04874.fb