Abstract

The dynamic nature of fish habitat use suggests that management requires proper knowledge in this filed. The overwintering movements of European grayling are belived to be directed towards more energetically and physiologically favourable habitats, but are inadequately studied. Radio telemetry and anchor-tagging recapture information was used to study the autumn migration in the 160km long unregulated river Kaitum, which flows through northern Sweden and eventually discharges into the Bothnian bay. The study was centred 3km downstream from lake Kaitum upon the Daivek rapid (67°36'N;19°04E), where the river stays ice-free from May-June to October with maximum temperatures of 13-15°C. During summer of 2000 to 2003, 447 grayling were caught by fly-fishing and anaesthetised, measured and weighted. 407 fish (mean LT:360mm, range 205-485mm) were anchor-tagged and 76 fish were later recaptured (mean LT: 381mm, range 230-485mm), whereby recapture sites were recorded. 40 fish (mean LT 411mm, range 360-450mm) were externally radio-tagged (transmittor model F1970, ATS Inc., weight; 4g) and traced by boat between July and November on average once a week using a hand-held receiver (Model R2100, ATS Inc.) and a 4-element Yagi antenna. The positions were deterimined by GPS when maximal signal strength was found using only the receiver cord. On average 90% were located at the first tracking, 55% at the last tracking and 27.5% on all occasions. Preliminary results indivate variation in migration speed during extensive upstream movements during late summer as well as multidirectional movements during autumn

Published in

Publisher: World Fisheries Congress

Conference

Fourth World Fisheries Congress

SLU Authors

• Hannersjö, David

  • Department of Aquaculture, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Environmental Sciences related to Agriculture and Land-use
Fish and Aquacultural Science


Permanent link to this page (URI)

https://res.slu.se/id/publ/4646