FISHING -- Numerous decades-old sturgeon being found dead in the Columbia River near the Tri-Cities are prompting a proposal to close catch-and-release fishing for the species.
The proposal is scheduled for consideration on Thursday, July 16, by the Columbia River Compact, the state agencies and tribes that co-manage the fisheries.
"We don't know the cause for sure, but sturgeon are obviously dying and stressed," Paul Hoffarth said today.
The Washington Department of Fish and Wildlife biologist found 16 dead sturgeon in what he calls a "once-over" sampling outing downstream from McNary Dam on Monday.
The fish were all in the large category, ranging from 5 feet to 8.5 feet, he said.
They were all feeding heavily on sockeye and their bellies were stuffed with the salmon, he said.
"But we couldn't find anything obviously wrong with them," he said.
Hoffarth has logged reports of at least 66 dead sturgeon in the Columbia River from McNary Dam to Boardman. More than 20 were reported upstream, from the Hanford Reach downstream to McNary Dam.
Theories for the sturgeon deaths include the possibility that the sockeyes they’re eating in this year’s big salmon run could be diseased from migrating upstream in the Columbia’s unusually warm water conditions.
Or maybe the big sturgeon are suffering consequences from simply gorging on sockeye in warm water conditions.
Another theory, Hoffarth said, suggests that the sturgeon are stressed by the combination of dramatically lower-than-normal Columbia flows with higher-than-normal July water temperatures.
Biologists are still gathering information and sending tissue samples to labs, Hoffarth said, noting that reports of dead sturgeon are coming in from McNary downstream to The Dalles.
"There's not necessarily a connection with catch-and-release fishing, but we can't rule that out," Hoffarth said.
"We know we're having temperature-related mortalities with sockeye. About 200,000 sockeye that passed over Bonneville Dam and should have made it up over McNary Dam, but they didn't. That's probably temperature related."
While fish managers can't improve river flows and cool water temperatures, they have the power to end catch-and-release sturgeon fishing until conditions improve, he said.
"We're scratching for answers," Hoffarth said.
"A similar sturgeon event occurred in Canada's Fraser River two years back. Scientists have been studying it for two years and they still haven't figured it out.
"The sturgeon could just be dying from a horrific confluence of events."