Retention Rates of Plastic-Infusion-Process Passive Integrated Transponder Tags and External Tags in the White-streaked Grouper Epinephelus ongus

AbstractFish are often externally tagged to determine the abundance, exploitation rates, and other key aspects of their ecology. Tag retention rates, however, may vary by tag type. The main objective of this study was to determine the retention rates of three external tags (Atkins, dart, and opercular tags) implanted onto White-streaked Groupers Epinephelus ongus in their natural habitat. White-streaked Groupers were tagged with different external tags, along with a plastic-infusion-process PIT (PIP PIT) tag, and retention rates were evaluated in experimental tanks for 54 weeks and in their natural habitat for 374 d. None of the fish kept in experimental tanks shed their abdominally implanted PIP PIT tags over 54 weeks. The mean retention rates of the external Atkins, dart, and opercular tags were considerably lower under natural conditions (16.7 ± 2.8%, 37.5 ± 3.3%, and 28.6 ± 3.4%, respectively) than in the laboratory (80%, 70%, and 70%, respectively). Loss of tags under natural conditions may have resu...