LAUSR

In fishes, differences in early rearing environment can have a significant impact on phenotypic development. In the present study, we examined the effect of differences in egg incubation (adhered to substrate or non-adhered and tumbled) and water temperature during early rearing on the development of escape response and volitional swimming performance in lake sturgeon, Acipenser fulvescens, throughout the first year of life. Developing embryos were incubated at 12–14 °C and supplied with flow-through aquarium water and ambient light conditions in McDonald hatching jars or allowed to adhere to substrate. Upon hatch (~ 9 days post-fertilisation, dpf), larvae from each incubation treatment were then acclimated to 16, 18 or 20 °C at a rate of 0.5 °C·day−1 and held at those temperatures until approximately 33 dpf. All treatments were then transferred to a common garden experiment where tanks were fed flow-through river water at ambient temperature and natural light cycles. Sturgeon were fed ad libitum twice daily throughout the growing season and food was withheld when water temperature reached 1.5 °C (~ 6 months post-hatch). Food was reintroduced at the start of spring the following year when water temperature exceeded 2 °C (~ 10.5 months post-hatch). There was no consistent effect of treatment on either volitional swimming or escape responses suggesting significant phenotypic plasticity in these measured traits during the first year of life. There was however an effect of time on these performance metrics that was most likely the result of seasonal differences in temperature throughout the 13-month study.