A comparison of Floy and soft Vlalpha tags on hatchery Arctic charr, with emphasis on tag retention, growth and survival

The Floy FTF-69 'fingerling' tag and the soft VIalpha tag are designed to be used on small salmonid fishes (> 100 and > 150 mm, respectively). The two tags were compared for 160 days on hatchery-reared Arctic charr, Salvelinus alpinus, (170-209 mm). Tag retention and effects on growth rate and survival were analysed. Vlalpha-tagged and untagged control fish had similar growth rates and grew significantly faster than Floy-tagged fish during the experiment. Tag retention was significantly higher for Floy tags (94%) than for VIalpha tags (78%). Most VIalpha tag loss (11%) took place within the first 10 days of tagging while there were no Floy tags lost during this period. Survival rates were about equal for all three groups (96-98%), and thus the tags did not seem to affect the survival of charr under hatchery conditions.