Post-release activity of three coral reef fish species in a marine reserve: analysis and recommendations for telemetry studies

We studied the post-release activity of newly tagged fish and determined whether and for how long experimental protocol impacted their behavior. Our study focused on three species (Plectropomus leopardus, Chlorurus microrhinos and Scarus ghobban), including a total of 30 fish. Fish were kept outside their natural environment for several days before release for pre- and post-tagging surveys. Moreover, 47% of them were not released at their capture site. Half of all individuals (all species) showed a high level of side fidelity immediately upon release. During this period, they were detected in the same place, by a small and constant number of hydrophones. This site fidelity pattern was also observed for the other fish (50%; all species) but after 1 to 18 days of an unsettled pattern, during which the fish moved significantly along the reef slope (high activity). During this short period, the distances travelled were significantly higher than during the subsequent period of site fidelity (several km vs. a few hundred m). We hypothesize that these unsettled patterns might result from fish experimental displacement (homing behavior) and from post-capture captivity (the fish had to recover a niche within the ecosystem). Consequently, we suggest that fish be released where they were caught to limit the movements associated with homing behavior. Periods of captivity should be avoided as much as possible. If this is not possible, a minimum acclimatization period of two or three weeks should be taken into account when analyzing the data.

Automated summary

The study examined the post-release activity of newly tagged fish and found a high level of site fidelity immediately after release, but an unsettled movement pattern for a period of 1 to 18 days before settling down. This may be due to experimental displacement and post-capture captivity, suggesting the importance of releasing fish at their capture site and avoiding prolonged periods of captivity.