Breeding-age sturgeon dying, possibly due to heat

Published 10:18 am Tuesday, July 21, 2015

As many as 80 large, broodstock-sized sturgeon were found dead last week in the Columbia River upstream of Bonneville Dam, triggering a complete closure of fishing for what some are calling “valuable, almost irreplaceable fish.”

Preliminary investigations point to warmer than average water temperatures as the cause of the die-off, prompting the two-state Columbia River Compact to close the river to recreational sturgeon fishing until further notice, effective Saturday, July 18 — an action that was unanimously supported by biologists and river guides alike.

At its July 16 call-in meeting, the Compact closed fishing from Bonneville Dam upstream to the Oregon and Washington border. The Washington Department of Fish and Wildlife immediately followed with a closure up through Hanford Reach, including adjacent tributaries.

“What we see in the river is extremely disturbing,” said WDFW’s Guy Norman. “Especially since it is happening to large, broodstock-sized sturgeon at a time when they are actively spawning. While there is no evidence that this is directly related to fishing, it is prudent to minimize the stress on these fish.”

River conditions are lower, warmer and clearer than recent five- and ten-year averages, according to Compact staff. Outflow at Bonneville Dam is 137,000 cubic feet per second, while the five-year average at this time of year (July 1-14) is 287,000. Water temperature at the dam is 73 degrees Fahrenheit, while the five-year average is 65 degrees.