Andrade, A. Effect of tagging with "T-anchor" tags on the survival and growth of Diplodus vulgaris (Geoffrey, 1817) and assessment of tag retention.

The objective of this study was to study the effect on growth and survival of the "T-anchor" tag used to tag individuals of Diplodus vulgaris (two-banded sea bream). In addition, tag efficiency in terms of retention rates was evaluated. A total of 240 two-banded sea breams (60 tagged with anaesthesia, 60 without and 120 control fish (untagged and not anaesthetised)) were used in this study and kept in 1130 litre experimental tanks during a period of 60 days. The growth and survival rates of fish anaesthetised with 2-Phenoxyethanol were compared with those of the other treatment. The results indicate that the anaesthetic had no effect on the survival and growth of the tagged sea breams. Survival was 100% and growth rates of anaesthetised and non-anaesthetised fish were 5.8% and 7.7% respectively. The presence of a tag attached to the body had no effect in terms of mortality or growth, with 99,16% survival of tagged fish. Tagged fish continued to grow and actually had higher growth rates than the control fish. High retention rates (97,5%) were obtained, indicating that the "T-anchor" tag is appropriate for this species.