Stocking of Advanced-Size Largemouth Bass in Two Estuarine Creeks and a Freshwater Impoundment in Southwest Alabama

The Mobile-Tensaw Delta is an 8231-ha oligohaline, tidal estuary that supports a popular largemouth bass (Micropterus salmoides) fishery. This system is productive, with an abundant bass population and above-average recruitment to age-1. But recruitment of the 2004 year-class was poor post-Hurricane Ivan, prompting angler concerns about the population. We considered improvements in the fishery were most likely achieved by stock- ing advanced-size fingerlings. Larger, older fish reared on live food were expected to provide a competitive advantage over native fish and exhibit higher survival than stocking smaller fingerlings. As this is an expensive venture, we tested this proposal in two tidal watersheds, Byrnes Lake and Threemile Creek, and a freshwater control, Monroe County Lake. During 2010–2014, a total of 16,380 advanced-size (97–354 mm TL) largemouth bass were tagged and stocked at approximately 10 months old. Abundance of wild fish was 5.0–77.5 times higher than stocked fish CPUE among sample areas, season and year. Percent contribution of stocked bass to individual cohorts was low, but highest at age-1, ranging from 2% to 31%. Percent contribution of stocked bass to cohorts decreased considerably after age-1, ranging from 1% to 16% and no tagged individuals were found after age-2 in Monroe County Lake. Length-frequency distributions differed between stocked and wild fish at all study areas pooled across years during spring, but distribu- tions did not differ in the fall. Success of fish stockings are linked to numerous factors, though competition with wild fish, size at stocking, and culture techniques are aspects to consider. This study was initiated well after fish populations had recovered and stocking likely was unnecessary given that fish populations are resilient to climate-induced fish kill events. State agencies should consider existing fish populations before stocking and long term recruitment data should be established prior to considering an extensive stocking program.

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