Feasibility of Oxytetracycline Marking Fingerling White Bass

Abstract

Chemical batch marks with compounds such as oxytetracycline hydrochloride (OTC) can be useful for estimates of stock contribution. However, no information currently exists on the feasibility of marking fingerling White Bass Morone chrysops with OTC. The objectives of this study were to determine the level of mortality on White Bass when immersed in solutions of OTC at 0, 350, and 500 mg/L at intervals up to 96 h postimmersion and to assess the quality of marks on sagittal otoliths 14 d postmarking. A total of 900 White Bass (29–41 mm) were utilized with 100 fish used in three replicates per treatment. No differences in mortality rates were detected among control and treatment groups up to 96 h postmarking. Cumulative mortality rates were ≤6.7%. Mark visibility was ranked on a scale of 0–3; mean mark score was higher in the 500-mg/L treatment (2.5) than the 350-mg/L treatment (2.0). Batch-marking fingerling White Bass using the 500-mg/L marking solution provided visible marks and low mortality rates and therefore represents a viable option for biologists seeking to assess stock contribution and year-class strength.

Received January 19, 2016; accepted May 27, 2016

ACKNOWLEDGMENTS

We thank Dirk Higgins and the North Platte Fish Hatchery staff for supplying the White Bass and assisting with OTC marking and fish transportation. We also thank Jim Gleim and the Calamus Fish Hatchery personnel for their assistance and the use of their facility. This project was funded by the Nebraska Game and Parks Commission through Federal Aid in Sport Fish Restoration, Project F-196-R.