Spatiotemporal use of a tributary by lake sturgeon over a 10-year period.

A telemetry study was conducted on lake sturgeon to determine the seasonal use and environmental factors that stimulate movement within a tributary of a larger system. Over a 10-year period, 52 lake sturgeon implanted with acoustic transmitters were monitored through an array of Vemco receivers with the Blanche River, Ontario. An average of 68% of the tagged fish entered the tributary annually whereas only 19.2% of those were detected on known spawning areas approximately 54 km upstream. Water temperature, lunar phase, lake water level, presumed spawning fish, and water discharge were all considered significant variables associated with the onset of upstream migration. Water temperature (mean 12.9 °C) was the only variable that explained the timing and the arrival at the spawning grounds. Sturgeon remained at the spawning area for a mean duration 7.9 days; however, none of the variables examined explained the duration of stay. Water temperature was the only variable that explained departure from the spawning areas (mean 15.8 °C). Mean time spent in the river after spawning was 30.5 days. There was not a significant difference in sex or total length in relationship to the duration tagged fish stayed in the river after spawning. The entire Blanche River up to the insuperable rapids was used by the sturgeon with the exception of minor tributaries. Water temperature, river discharge, and fish size were all considered significant factors initiating out-migration back into the lake. This study demonstrated the importance and seasonal use of a tributary by lake sturgeon. Correlations from abiotic variable and seasonal response could be used to establish guidelines for water management purposes when the goal is to conserve or restore sturgeon populations within a river system. This study also illustrates the importance of tributaries in association to a larger waterbody for lake sturgeon. [ABSTRACT FROM AUTHOR]