Effects of tagging on migration behaviour, survival and growth of hatchery-reared Atlantic salmon
The effects of four different tagging methods (PIT, anchor T-tag, Carlin tag and dummy radio transmitter) on survival, behaviour and growth of Atlantic salmon smolts during their downstream migration were examined in semi-natural circular channels during a natural migration period in spring. Survival of smolts was high and tagging wounds healed well in all tagging groups. Tag loss rates were generally low, being the highest (2.5%) in the dummy radio transmitter group. Total length and body mass of the tagged and untagged smolts did not differ at the end of the experiment. Migration activity of smolts generally showed similar patterns among the treatments. However, Carlin-tagged smolts started their migration slightly later than the PIT-tagged fish, and smolts tagged with Carlin tag or dummy radio transmitter showed less overall migration activity than fish with PIT tag.