Evaluation of Visible Implant Elastomer for Marking Juvenile Red Drum

Abstract

Visible implant elastomer (VIE) was evaluated for marking juvenile red drum Sciaenops ocellatus in experimental studies. We tested VIE on hatchery-reared red drum (standard length, 29.6–38.7 mm; SE, 0.23) in a laboratory study to examine mortality, tag retention, and growth effects associated with the marking method. We examined two tagging locations and two control treatments in anesthetized and unanesthetized fish. Red drum were tagged below and parallel to the dorsal fin and above and parallel to the anal fin. Five fish were anesthetized, marked, and stocked into replicated tanks and held for 14 d. Tag retention was 100%, and overall mortality was 10%. The mortality of fish tagged below the dorsal fin was 0%, whereas that of fish tagged above the anal fin was 40% (SE, 30.5). No significant difference in growth rates was observed between the marked and unmarked treatment groups. A field study was performed with wild and hatchery-reared red drum marked with VIE and released at three replicate sites in sea grass beds. The recapture rate was 1.3%, and marked fish were collected at 1 and 3 d postrelease at distances of 15–45 and 200 m from the release point. The results suggest that VIE marking of red drum has little effect on mortality and growth when fish are tagged dorsally and that VIE is a viable tool for short-term experiments requiring identification of small, juvenile red drum.