Efficacy of Oxytetracycline Marking of Fingerling Palmetto Bass in Hard Water

Abstract

An oxytetracycline hydrochloride (OTC) marking study was used to determine an OTC concentration that would successfully mark palmetto bass (male white bass Morone chrysops × female striped bass M. saxatilis) in hard hatchery water (hardness as CaCO₃ = 500 mg/L). Outcomes for juvenile palmetto bass immersed for 6 h in 500- and 700-mg/L concentrations of OTC mixed with hard water were compared to determine whether 14-d marking mortality and mark intensity at 14 and 344 d postimmersion differed between immersion concentrations. Sagittal otoliths were examined for marks at 14 d; lapillus otoliths were examined for marks at 344 d. Marking mortality was not detectable after 14 d, but identification and intensity of sagittal otolith marks at 14 d postimmersion were poor for both OTC concentrations. Oxytetracycline marks were identified in 63% (500 mg/L) and 74% (700 mg/L) of the sagittae examined at 14-d postimmersion, whereas marks were found in 87% (500 mg/L) and 95% (700 mg/L) of lapilli examined at 344 d postimmersion. The 700-mg/L OTC concentration yielded better mark intensity results than the 500-mg/L concentration in lapilli at 344 d postimmersion.