Experimental and field evidence of behavioural habitat selection by juvenile Atlantic Acipenser oxyrinchus oxyrinchus and shortnose Acipenser brevirostrum sturgeons

The present work reports behavioural responses by young-of-the-year (21-30 cm) Atlantic sturgeon Acipenser oxyrinchus oxyrinchus and shortnose sturgeon Acipenser brevirostrum to nine binary combinations of dissolved oxygen saturation (40, 70 and 100%), temperature (12, 20 and 28°C) and salinity (1, 8 and 15). Both species showed no acclimation effects and similar discrimination and avoidance reactions to hypoxia (40% oxygen saturation), selecting higher dissolved oxygen choices in 71% of the tests. Acipenser oxyrinchus oxyrinchus and A. brevirostrum showed a similar preference for 20°C (>64% incidence), but differed in their responses to extreme temperature choices. Acipenser brevirostrum showed a significant avoidance behaviour to the 12°C but not to the 28°C choice. In contrast, A. o. oxyrinchus showed similar preference for 12 and 20°C, but avoided the 28°C choice in 71% of the tests where this temperature was included (P < 0·01). No significant preferences were observed among salinity choices, except between salinities 1 and 8, where A. o. oxyrinchus showed a significant preference for salinity 8. Behavioural responses matched expectations from bioenergetics in both species and were also consistent with the distribution of juvenile A. o. oxyrinchus capture locations in the Chesapeake Bay.