Cooperative Fish and Wildlife Research Units Program: Tennessee
Education, Research and Technical Assistance for Managing Our Natural Resources

Hoffman, K., and P. W. Bettoli. 2005. The fate of largemouth bass marked with oxytetracycline and stocked into Chickamauga Lake, Tennessee. North American Journal of Fisheries Management 25:1518-1527.


We evaluated a largemouth bass Micropterus salmoides fingerling stocking program by stocking marked fish and sampling them for one year. More than 128,000 fingerlings (35-64 mm total length) were immersed in a solution of 500 mg/L oxytetracycline (OTC) for 6 h and stocked into four embayments in Chickamauga Lake, Tennessee, in spring 2002; two control embayments were not stocked. In a blind-test, 97% of sagittal otoliths were correctly scored as marked or unmarked. In a subsequent test, the OTC marks were clearly visible on every otolith removed from 240 OTC-treated bass held for 30 d. Age-0 largemouth bass were sampled 7-19, 44-61, and 119-139 d after stocking along 100-m transects within 1 km of the stocking sites in each embayment using DC electrofishing gear. Thirty-one percent of all recaptures in the first sample occurred more than 600 m from the nearest stocking site, indicating rapid dispersal by some fish. Survival of stocked and wild age-0 largemouth bass was similar and low (4.5 - 6.9%) in two embayments; in the other two embayments, stocked fish survived at lower rates (0 – 4.3%) than wild fish (33.7 – 49.9%). Mean catches of all age-0 largemouth bass in the first sample were positively related to the number of fish stocked. By October 2002, the mean catch of all age-0 largemouth bass was similar among embayments. The percent contribution of stocked fish declined to approximately 2% (2 of 91 fish) the following spring. Cost per fingerling increased from US$0.35 at stocking to $12.00 at 140 days post-stocking. Increasing the abundance of largemouth bass was not the primary objective of this stocking effort, but stocked fish will have to survive much better if managers hope to introgress Florida largemouth bass genes into the resident population genome.