An Evaluation of Coded Wire and Elastomer Tag Performance in Juvenile Common Snook under Field and Laboratory Conditions

Abstract

From 1997 to 2002, retention of coded wire tags (CWTs) and visible implant elastomer (VIE) tags was evaluated in a series of stock enhancement studies with common snook Centropomus undecimalis (60–230 mm fork length (FL)). These experiments were conducted in both field and laboratory settings in Sarasota, Florida. Retention rates of CWTs were stable after 30 d and remained greater than 97% even 1 year after tagging. Retention of VIE tags was compared among different body implant locations, implant techniques, and fish sizes. Body location had the strongest influence on VIE retention, and tags implanted in the fins (anal and caudal) had significantly higher retention rates (mean ± SE = 76 ± 9%) than those implanted in the head (adipose eyelid, jaw, and preorbital nose tissue; 5.6 ± 1.8%, P = 0.038) 1 year after tagging. After 1 year, however, most VIE tags—regardless of body location—were nearly indistinguishable or lost. Fish implanted with two VIE marks had consistently higher mean tag retention rates and visibility than those with single marks (86% versus 64% mean retention in the caudal fins 7–12 months after tagging). Fish size at tagging was not a significant contributor to tag loss. Tagging rates were slowest with VIEs: 250–400 fish per hour and 200–300 fish per hour when one and two VIE marks, respectively, were injected per fish. Tagging mortality was less than 1.6%. No significant differences in tag retention or mortality were found between field and laboratory trials. Overall, we recommend CWTs implanted in cheek muscle and at least two VIE marks implanted in the caudal fin as tagging methods and locations for juvenile common snook because of the ability to tag large numbers of fish, high tag retention, and low tagging mortality.