Hatchery rearing environment and age affect survival and movements of stocked juvenile lake sturgeon

Abstract

Considerable uncertainty exists over the relative merits of alternative supplementation strategies for lake sturgeon, Acipenser fulvescens Rafinesque. Numerous supplementation prescriptions have been advocated, largely in the absence of data, focusing on perceived impacts of levels of genetic diversity of progeny collected using different collection methods, and probabilities of survival relative to the size or age of fish released. The hypothesis that collection method, hatchery rearing environment and size/age at the time of release do not influence survival and movements was tested. Acipenser fulvescens gametes and juveniles were collected using three methods and reared in a stream-side hatchery along the natal stream and in a traditional non-natal hatchery environment. Acipenser fulvescens were released into the Upper Black River, Michigan at 8, 13, and 17 weeks of age. Higher rates of recapture were found for juvenile sturgeon reared in the stream-side hatchery than the traditional hatchery for the releases at 8 and 13 weeks. Recapture rates and dispersal distances were significantly greater for fish stocked at 17 weeks than for fish released at earlier ages. Large body size was negatively correlated with timing of movements across all ages indicating that survival may be enhanced by releasing individuals at night. Results indicate that supplementation protocols for A. fulvescens should be developed on a system specific basis and demonstrate the importance of hatchery-rearing environment when fish of younger ages are released. K E Y W O R D S :Acipenser fulvescens, collection methods, dispersal, supplementation.

Effects of rearing practice on post-release young-of-the-year behavior: Acipenser sturio early life in freshwater

“…The overall survival rate in this study (69.3%) is acceptable given the estimates from other studies on YOY hatchery-reared sturgeons: 40% (Crossman et al 2009) and 5 to 15% (Crossman et al 2011) in lake sturgeon Acipenser fulvescens released at 6 and 2 to 4 mo old respectively, and 87% in European sturgeon re leased at 9 to 12 mo old (Acolas et al 2012). Nevertheless, monitoring duration and fish age varied among those studies and thus an accurate comparison is not possible.…”

“…These results would be congruent with studies done on YOY lake sturgeon, where 3 mo old fish had fewer recapture rates when reared traditionally than under a more enriched approach (ca. 2 to 4 fold higher) (Crossman et al 2011). Nevertheless, there were no differences due to rearing for 4 and 6 mo old fish, suggesting that the influence of rearing may decrease with fish age (Crossman et al 2009(Crossman et al , 2011.…”

“…2 to 4 fold higher) (Crossman et al 2011). Nevertheless, there were no differences due to rearing for 4 and 6 mo old fish, suggesting that the influence of rearing may decrease with fish age (Crossman et al 2009(Crossman et al , 2011. In addition, there are other studies where improved post-release survival has been obtained using more enriched rearing approaches: 3.5% higher in common snook Centropomus undecimalis (Brennan et al 2006) and 6.4 and 19% higher in Atlantic salmon Salmo salar (Hyvärinen et al 2013, Roberts et al 2014.…”

Relative recruitment success of stocked age-1 vs age-0 lake sturgeon (Acipenser fulvescens Rafinesque, 1817) in the Nelson River, northern Canada

“…At least a proportion of the stocked progeny must survive to adulthood and reproduce in order to make contributions to the next generation (Brown and Day, 2002;Secor et al, 2002), and the optimal age (or size) at which to stock out Lake Sturgeon will be influenced by post-stocking survival rates. Mean recovery rates (shortly after stocking) of Lake Sturgeon stocked at 8, 13, and 17 weeks of age were 0.05, 0.1 and 0.15, suggesting increased survival with age (Crossman et al, 2011). Overwinter survival rates for Lake Sturgeon stocked out at the fingerling stage (age-0, 6 months post hatch) were determined to be at least 0.4 (Crossman et al, 2009).…”

Review of a species in peril: what we do not know about lake sturgeon may kill them

“…Rearing and stocking of lake sturgeon is not without its problems and has historically been a difficult task (Ć eskleba et al 1985). For example, Crossman et al (2011a) investigated several issues related to stocking including collection method, rearing environment, and size at release and found that recapture rates and dispersal distances were significantly greater for sturgeon stocked at 17 weeks compared with fish released at earlier ages. Large body size was negatively correlated with timing of movements across all ages, indicating that survival may be enhanced by releasing individuals at night.…”