LONG-TERM RETENTION AND DETECTION OF OXYTETRACYCLINE MARKS APPLIED TOHATCHERY-REARED LARVAL STRIPED BASS, MORONE-SAXATILIS

Hatchery-reared larval striped bass, Mot-one saxatilis, destined for s tocking in the Savannah River, Georgia, were immersed in oxytetracycli ne (OTC) to mark bony structures for later identification. Approximate ly 170000 of these fish were raised to larger sizes and tagged with mi cromagnetic coded-wire tags (CWT). Recaptures of OTC-marked (OTC only) and marked and tagged (OTC and CWT) fish allowed us to determine rete ntion of the OTC mark in otoliths to 3 years of age and to evaluate re ader ability to detect those marks. The estimated retention rate was 8 0.2% for the first year, with no detectable change in additional years . Detection of OTC was age independent and estimated at 72.6% when one otolith was examined versus 92.5% when both otoliths were examined. O nly 74.2% (retention x detection) of recaptures in this study would ha ve been correctly identified as stocked fish if OTC alone was used as the marking method.