Effects of hatchery rearing on Florida largemouth bass Micropterus floridanus resource allocation and performance under semi‐natural conditions

Abstract

This study examined the growth, activity, metabolism and post-release survival of three groups of Florida largemouth bass Micropterus floridanus: wild-caught fish, hatchery fish reared according to standard practice (hatchery standard) and hatchery fish reared under reduced and unpredictable food provisioning (hatchery manipulated). Hatchery-standard fish differed from wild-caught fish in all measured variables, including survival in semi-natural ponds. Hatchery-standard and hatchery-manipulated fish showed higher activity levels, faster growth and lower standard metabolic rates than wild-caught fish in the hatchery. Fish reared under the manipulated feeding regime showed increased metabolic rates and increased post-release growth, similar to wild-caught fish. Their activity levels and post-release survival, however, remained similar to those of hatchery-standard fish. Activity was negatively correlated with post-release survival and failure of the feed manipulation to reduce activity may have contributed to its failure to improve post-release survival. Activity and post-release survival may be influenced by characteristics of the rearing environment other than the feeding regime, such as stock density or water flow rates.

Survival of Pellet‐Reared, Naturalized, and Wild Advanced‐Size Largemouth Bass Exposed to Angling and Handling Stressors

“…Our findings are not in agreement with Garlock et al. () who found lower survival of intensively reared juvenile Florida Bass M. salmoides floridanus than of wild Florida Bass when bass were stocked into hatchery ponds containing Florida Bass predators. Garlock et al.…”

“…Not considered by Garlock et al. () was the difference in sizes of juvenile fish; the intensively reared juvenile Florida Bass were 75–125 mm TL, whereas the wild juvenile Florida Bass were 100–180 mm TL. Lower survival of smaller fish stocked into environments with predators has been repeatedly demonstrated (Yule et al.…”

“…Garlock et al. () attributed the lower survival of the intensively reared fish to being reared in 328‐L tanks and fed prepared feeds for 3 months prior to being fed live forage for 1 week before stocking into an experimental pond containing predators. Not considered by Garlock et al.…”

Behavioural and fitness effects of translocation to a novel environment: Whole‐lake experiments in two aquatic top predators

“…Maladjusted behaviour and elevated mortality in stocked hatchery fish has been documented in a range of species (Lorenzen, 2006; Lorenzen et al, 2012). These impacts are typically attributed to domestication effects stemming from hatcheries (Garlock, Monk, Lorenzen, Matthews, & St Mary, 2014; Lorenzen et al, 2012), relaxed natural selection in a hatchery (Araki et al, 2008), the release of a life stage with high density‐dependent mortality (Hühn, Lübke, et al, 2014; Lorenzen, 2005) and a lack of life‐skills training to cope with natural challenges (Brown, Ferrari, & Chivers, 2013; Olla et al, 1998; Sloychuk, Chivers, & Ferrari, 2016). In contrast to most stocking studies, we stocked wild fishes, which have had full life‐skill training and full access to natural prey and predators in their original environment.…”

“…The translocated pike overwhelmingly produced hybrids with resident pike, thereby adding to gene flow from the non‐local genotypes into the resident population. The reproductive success of the translocated individuals may firstly be attributed to the absence of domestication effects typical of stocked fish (Lorenzen et al, 2012), which may fundamentally alter the life‐history trajectories of the fish in a manner that might downplay reproductive allocation in favour of growth (Garlock et al, 2014; Lorenzen et al, 2012). Secondly, the translocated fish were introduced from nearby lakes with similar limnological characteristics, and therefore the spawning conditions and timing were probably similar to Kleiner Döllnsee.…”