Fishery Dynamics of Macrophyte-dominated Banks Lake National Wildlife Refuge, Georgia

Banks Lake National Wildlife Refuge is a 1,640-ha refuge consisting of 405 ha open water (Banks Lake) and 1,235 ha of cypress swamp, marsh, and uplands located in southern Georgia. Fishes from Banks Lake, a system with problematic densities of both indigenous and nonindigenous aquatic vegetation, were collected during eight sampling periods in open water habitats from 1992 through 2003 to evaluate assemblage and sportfish dynamics. Stability and persistence analyses indicated that the fish assemblage was stable and persistent over time, though catch per unit effort of assemblage members was low in most years sampled. The bluegill population appeared stunted and was characterized by low relative weights (Wr) and proportional stock densities (PSD), while the largemouth bass population had low Wr and medium to high PSDs throughout the sample period. Length, weight, and structural indices for these fishes were characteristic of populations in a system with excessive vegetation. An experimental drawdown to control aquatic vegetation during winter 1993-94 resulted in a short-term increase in largemouth bass Wr and shift in bluegill size-distributions. Low system productivity and high concentrations of aquatic vegetation likely drive the population dynamics of the Banks Lake fish assemblage, thus future drawdowns or other vegetation-control actions may be an effective technique for improving its fishery. Key words: Banks Lake National Wildlife Refuge, aquatic vegetation, fishery assemblage, stunting

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