A split decision: the impact of substrate type on the swimming behaviour, substrate preference and UCrit of juvenile shortnose sturgeon (Acipenser brevirostrum)

Abstract

Critical swimming speed (UCrit) is a standard test to measure sustained swimming capabilities of fish species, however, much of this research is focused on pelagic fish or popular game fish. Recently, more research is emerging on the swimming capabilities of sturgeons, mainly due to their conservation status. Substrate preference has been examined in sturgeons, however, few studies have investigated whether sturgeon would select for a particular substrate (smooth or pebble) when provided a choice under high-flow conditions, as irregular shaped bottom substrates may provide an energetic advantage. Critical swimming tests were performed in a linear flume to evaluate whether substrate (smooth, pebble, pebble on the left side of the flume/smooth on the right side of the flume, and pebble on the right side of the flume/smooth on the left side of the flume) would affect UCrit of juvenile shortnose sturgeon (Acipenser brevirostrum), and if the sturgeon would select for a particular substrate at different speeds. All swimming experiments were video recorded and subsequently reviewed to determine the amount of time individual sturgeon spent in particular sections of the flume. Overall, there was no clear preference for a particular substrate and substrate configuration did not affect UCrit. These results may be attributed to small sample sizes, and the small pebble sizes used in relation to the sturgeon’s body size may not elicit an energetic advantage.