Survival and Growth of Lake Sturgeon during Early Life Stages as a Function of Rearing Environment

Abstract

AbstractThe need for hatchery programs to reflect the latest scientific knowledge is critical for understudied groups with unique ecologies such as Acipenseriform species, including Lake Sturgeon Acipenser fulvescens. In order to address uncertainties regarding the efficacy of Lake Sturgeon culture techniques, we quantified and compared growth and survival at the egg, larval, and juvenile life history stages as a function of hatchery rearing environment over 2 years (two cohorts). Furthermore, we evaluated growth and survival of juveniles produced from three methods of progeny collection including direct gamete takes, collection of naturally spawned eggs from the stream substrate, and collection of larvae dispersing downstream from the spawning grounds. Progeny from each collection method were evenly divided between a streamside hatchery on the natal river and a traditional hatchery. Progeny reared at the streamside hatchery experienced a natural temperature regime and were exposed to natal water only filtered to remove larger sediments. We found that daily survival at the egg stage varied as a function of hatchery environment, duration of incubation, and maternal sources. Microbial infection during incubation contributed significantly to mortality, was higher, and occurred earlier in the incubation period at the streamside hatchery than at the traditional hatchery. Hatching rate was significantly higher at the streamside hatchery in 2006 than at the traditional hatchery. Daily survival at the larval stage was high at both hatcheries but was significantly higher at the streamside hatchery in 2006. Importantly, survival of progeny collected as dispersing larvae was significantly lower during the first week of rearing in both hatchery environments and years. Growth rates at the juvenile stage were comparable between hatcheries and inter‐individual variation in growth increased through the rearing period in both years. Natural temperature regimes resulted in variable egg incubation time and concomitant variation in larval size at hatch that extended into the juvenile stage. Results indicate conservation hatchery programs that incorporate rearing environments reflective of natural conditions can increase phenotypic variation in stocked progeny without compromising survival in the hatchery.