Increasing Largemouth Bass Carrying Capacity Using Destratification: A Case Study

Aeration can circulate waters by disrupting thermal density differences associated with stratification, allowing homogenization of tempera- ture, oxygen, and other physicochemical characteristics within the water body. Use of lake and pond destratification as a management tool has been increasing in recent years, yet data are limited regarding its effects on fish communities. This case study examines the response of a largemouth bass (Micropterus salmoides) population to destratification in a 2.4-ha pond over nearly a decade. Biomass (35.8–42.8 kg ha–1) and density (51–93 fish ha–1) of stock-sized (≥200 mm TL) largemouth bass were consistently low prior to installation of the system; however, biomass tripled (129.8 kg ha–1) and density quadrupled (334 fish ha–1) 3.5 years after system initiation and remained high for the duration of the study. In contrast, mean weight and mean relative weight (Wr) of fish declined continuously following population expansion, suggesting that population biomass had exceeded carrying capacity. Although this study was limited to a single waterbody, the rapidity and magnitude of observed changes following years of relative stability suggests that continuous destratification increased carrying capacity for largemouth bass in this case study. These findings may have applications to other ponds characterized by anoxic hypolimnions, and more research on the effects of destratification in small impoundments is warranted. If destratification can increase standing biomass two- or three-fold, while greatly reducing the risks of oxygen-related fish kills, the cost of these systems could be more easily justified by managers of ponds and small lakes.

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