Poststocking Survival of Conditioned and Pond‐Reared Compared to Indoor Pellet‐Reared Advanced Fingerling Florida Bass

Abstract

AbstractSupplemental stocking of hatchery Largemouth Bass Micropterus salmoides and Florida Largemouth Bass Micropterus salmoides floridanus (hereafter, Florida Bass) is a common practice around the world, but the results commonly do not meet expectations. Predation upon stocked fish and the inefficiency of stocked fish in capturing wild prey are common reasons for low poststocking survival rates of hatchery fish. Standard protocol for rearing Florida Bass in Florida includes growing fish out in indoor raceways with pellet feed until 5 d prior to stocking, when live prey is introduced. We conducted a 3‐year study to determine whether extended conditioning in outdoor ponds, exposure to predators prior to stocking, or rearing in ponds rather than indoor raceways could increase the survival of hatchery‐reared Florida Bass. One month after stocking, mean survival for standard hatchery‐reared fish that received pellets was 36% (SE = 4.3) across all 3 years. Mean survival was 63% (SE = 4.7) for experimental fish conditioned with predators (E‐CWP), 41% (SE = 4.8) for fish conditioned without predators (E‐CWOP), and 63% (SE = 5.4) for fish raised on live prey in outdoor ponds in the absence of predators (E‐PR). While stocked in research ponds, E‐CWP and E‐PR fish had higher growth rates than standard pellet‐reared fish. During laboratory trials to measure predator avoidance rates, which began 24 h after experimental ponds were stocked, standard pellet‐reared fish had a mean 48‐h survival rate of 84% (SE = 6.6). Mean 48‐h survival for the E‐CWP, E‐CWOP, and E‐PR groups was 96% (SE = 1.9), 84% (SE = 7.2), and 95% (SE = 3.1), respectively. Our experiments indicate that being reared outside or conditioning to a natural environment and exposure to predators may increase poststocking survival of hatchery‐reared Florida Bass.