Influence of habitat and other factors on Largemouth Bass abundance in Lake Okeechobee, Florida

Objective: Submerged aquatic vegetation (SAV) is an important part of shallow lake ecosystems. It provides protective cover and foraging habitat for age-0 and juvenile Largemouth Bass Micropterus salmoides and other small fish, creates structure and habitat for macroinvertebrates and other fauna, and can influence the physical environment by stabilizing sediments and reducing water column turbidity. Methods: For this study, we reviewed annual abundance data for Largemouth Bass collected via electrofishing from 2002 to 2019, along with environmental covariates that included SAV cover (habitat) and turbidity. Result: All age-groups of Largemouth Bass were positively correlated with vascular SAV cover. Age-0 Largemouth Bass were most abundant when SAV cover exceeded approximately 24% (9400 ha) of the littoral and nearshore area, while the juvenile and all-ages groups were most abundant when SAV cover exceeded 20% and 12% of the area, respectively. Following major storm events, water depth and turbidity increased, SAV cover was reduced to <5% of the littoral and nearshore area, and the abundance of age-0 Largemouth Bass was reduced more than 90%. Conclusion: Once removed from the landscape and exposed to turbid conditions, vascular SAV will reestablish only if water clarity increases and light is sufficient to support plant growth. Lowering water levels for an extended period has been shown to reduce nearshore turbidity and jumpstart the recovery of SAV in Lake Okeechobee and other shallow lakes globally. Without adequate SAV habitat, recruitment of age-0 and juvenile Largemouth Bass will likely be suppressed. Maintaining a minimum coverage of vascular SAV (20-35%) in the littoral and nearshore area should increase the abundance of age-0 and juvenile Largemouth Bass and provide beneficial habitat for adult Largemouth Bass and other lake fauna.