Retention of Passive Integrated Transponder Tags in Flathead Catfish

We evaluated short- and long-term retention of passive integrated transponder (PIT) tags at two anatomical tagging locations in flathead catfish Pylodictis olivaris (n = 72 fish; total length range = 421-854 mm). Tags were injected into the dorsal musculature immediately posterior to the dorsal fin and into the opercular musculature immediately posterior to the left eye. Short-term tag retention evaluated at 1, 3, and 7 d posttagging was 100% at both tagging locations after accounting for one tag failure (at the dorsal musculature site) that occured during the initial tagging procedure. Long-term (300-d) tag retention was 100% for the dorsal musculature site and 98.5% for the opercular site. Mortality of tagged fish was low (8%): the mortalities that did occur were probably not related to tagging. Our results indicate a high rate of PIT tag retention in flathead catfish at both anatomical locations. Additionally, utilization of the opercular musculature as a PIT tagging location for this species may reduce the potential for accidental tag consumption by anglers.