Evaluation of the Impacts of Carlin Tags, Fin Clips, and Panjet Tattoos on Juvenile Atlantic Salmon

Abstract

The potential impacts of marking techniques on juvenile Atlantic salmon Salmo salar were assessed in a hatchery and in the wild. Hatchery-reared parr ranging from 12.0 to 20.8 cm were marked with Carlin tags and fin-clipped. Anal, pelvic, or caudal fin clips were used to investigate the rate of fin regeneration. No mortality or tag loss occurred, and there was no significant change in condition factor between marked and unmarked treatments or among fish of different mark groups. Carlin tag wounds began to heal within 28 d. However, this was followed by a period where the majority of wounds became irritated, thus slowing the healing process; thereafter, the majority of individuals showed an accelerated healing that continued until the end of the hatchery experiment (146 d). Caudal fins showed the first signs of regeneration, and pelvic fins showed the greatest amount of regeneration by the end of the experiment (146 d). Anal fins showed significantly less fin regeneration than pelvic or caudal fin clips and so were used as a secondary mark in the field to investigate differences in survival and mark retention between Panjet tattoos and Carlin tags. Panjet-tattooed and Carlin-tagged smolts held for 24 h posthandling showed no difference in survival (97% overall), and mark retention was 100%. Recapture success was equivalent between tagged and tattooed individuals, and none of the recaptured smolts showed evidence of tag loss. The results of this study provide evidence of the efficacy in using anal fin clips, tattoos, and Carlin tags as marking techniques in fisheries research.