Comparing tagging strategies: Effects of tags on retention rate, mortality rate and growth in hatchery-reared juvenile meagre, Argyrosomus regius (Pisces: Sciaenidae)

Abstract

The objective of this study was to compare the effectiveness of different tags (T-bar anchor tags, internal anchor tags and visible implant elastomers) implanted into juvenile meagre, Argyrosomus regius (Asso, 1801) for a restocking programme conducted in the Balearic Islands. Effectiveness was assessed in terms of tag loss, fish survival and fish growth by means of a tank experiment. The internal anchor tags showed the highest retention rate (100%), but the tagging mortality was also high (40%). The tagging mortality of T-bar tags was negligible. However, another tank experiment with different food rates showed the tag retention rate of the T-bar tag to be highly variable, ranging from 35% to 95%. In contrast with other reported results, the retention rate of visible implant elastomers was low (48%). Finally, none of the tested tags affected growth. In summary, the T-bar anchor tags showed the best trade-off between short-term tag retention and fish mortality, and seem to be the most suitable tagging method for meagre juveniles.