Current production of Largemouth Bass (LMB) in the Midwest is carried out in ponds, which typically leads to high variation in survival and growth. This is due to increased cannibalism, predation, and inconsistency in feed consumption associated with low-density ponds. This study sought to evaluate two alternative pond-based production systems for the rearing of LMB. Specifically, the aim of this study was to evaluate two alternative pond-based production systems (split ponds and pond-side tank culture) on LMB quantified production parameters.
A total of 9 systems were utilized, with 3 replicates of each treatment (split pond, SP; pond side tank, TK; & full pond system; FP). Each pond utilized was ~ 0.1 acre, with a maximum depth of 1.5 m. The SP treatments were equipped with a T-shaped baffle to hold the LMB in < 25% of the pond’s area and direct the flow of water in a U-shaped fashion around the non-fish side before returning to the fish-side. A TK consisted of a 4.6 m³ plastic tank set on the side of the pond, supplied with blower aeration and water from an adjacent full pond. Each system was stocked with 1,250 feed-trained LMB fingerlings in June 2024 at an average size of 58.02 mm (± 2.71) and 2.18 g (± 0.39). Fish were fed twice daily with a restricted feeding rate. The feeding amount was adjusted daily based on an assumed FCR of 1, and the rate adjusted biweekly based on the subsampling of 25 LMB from each system. Final data collection gathered total count of surviving fish and length/weight data for 100 fish from each system.
The study was concluded in late September 2024, with data still being processed. Initial data analysis revealed noteworthy trends in production differences between the alternative rearing systems and the FP treatment. The TK treatment showed numerically lower final weight, final length, specific growth rate, production efficiency, and survival of LMB compared to the FP and SP treatments. With regards to the FP and SP treatments, the survival, production, and growth parameters were found to be similar between systems. An important trend observed was that the coefficient of variation of fish length (Figure 1) and weight decreased numerically as the area of the rearing system decreased. While this decreased variation occurred with decreased growth and survival in the TK treatment, the SP treatment was able to achieve more uniform growth than the FP, with similar production parameters. Uniformity of growth in desirable in LMB rearing, as there is a reduced occurrence of cannibalism, and a more synchronized achievement of market-size in the farmed fish. More details will be presented in the oral presentation.