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

Abstract

Supplemental 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.

Reared to become wild-like: addressing behavioral and cognitive deficits in cultured aquatic animals destined for stocking into natural environments—a critical review

“…Sockeye salmon (Oncorhynchus nerka) fry instead increased their survival with increased exposure to predators in an experimental stream, mediated through increased shoaling tendency (Ginetz and Larkin 1976). Similarly, Florida bass (Micropterus floridanus) showed improved poststocking survival after a 10-d exposure to predators in an earthen pond (Trippel et al 2018). From a management perspective, these studies are interesting as they can be relatively easy to implement, as long as there is access to (semi-)natural ponds from which the animals can be easily retrieved.…”

Survival of Advanced‐Fingerlings of Florida Largemouth Bass Stocked in Small Florida Lakes

“…Nevertheless, to justify the additional work that is required at a production scale, conditioning would need to improve survival substantially. It is unclear whether any benefits of conditioning hatchery fish to natural forage and the presence of predators, demonstrated in tank and pond studies (Sclechte et al 2005;Schlechte and Buckmeier 2006;Trippel 2018), would be realized in Florida Bass that are stocked into the wild. While our results suggest that conditioning did not substantially improve survival when using in-lake enclosures, we feel that this idea is worthy of further evaluation using modified or alternative methods.…”

“…Along with size and the timing of stocking Largemouth Bass, conditioning (i.e., acclimating to the natural environment) the fish before stocking them may improve their survival rate (Schlechte and Buckmeier 2006;Trippel et al 2018) and capacity to augment existing populations. Intensive hatchery rearing of Florida Bass on pelletized feed in SURVIVAL OF ADVANCED-FINGERLING FLORIDA LARGEMOUTH BASS raceways gives the hatcheries more protection from environmental conditions and can increase production.…”

“…There is some evidence that conditioning works. For example, Trippel et al (2018) found that exposing pellet-reared Florida Bass to natural prey, predators, and habitat for 10 d in earthen ponds increased their poststocking survival rate postrelease into research ponds by day 30. However, conditioning large numbers of Florida Bass typically requires significant hatchery pond acreage that may render it infeasible on a production scale.…”

How Stocking Recreational Fisheries Works (and Sometimes Does not)

“…Raising larger fish can be tricky. They may eat each other, get diseases, and take up more hatchery space (Trippel et al 2018). It can also be really expensive.…”