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Smaller Columbia River Fish Returns
Constrain Harvests; Blob Cited as Factor

by Laura Berg
Northwest Fishletter, September 5, 2017

Gillnetters in lower Columbia River fish 9 pm-6 am. (Credit: Oregon Public Broadcasting) Fall Chinook are once again expected to be one of the standouts of this year's salmon and steelhead returns, with 613,800 fish expected, or 84 percent of the 10-year average, according to a joint staff report of the Oregon and Washington fish and wildlife departments released Aug. 16.

The 2017 forecast estimates the returns at 613,800 fish, or 84 percent of the fall Chinook 10-year average.

The Bonneville Dam passage returns are predicted to total nearly 403,600 upriver fall Chinook.

However, the current return of fall Chinook at Bonneville Dam is around 50,000, or only about 60 percent, of the 10-year average, said NOAA Fisheries representative Paul Wagner at the Aug. 30 Technical Management Team meeting. Passage is usually 50-percent complete by Sept. 9.

The Nez Perce, Umatilla, Warm Springs, and Yakama tribes began a truncated commercial fishery on upriver Chinook Aug. 21.

At the meeting, Kyle Dittmer of the Columbia River Inter-Tribal Fish Commission asked the federal action agencies to keep the three lower Columbia River pools within a 1.5-foot elevation band to facilitate the tribal fishery, which takes place in the reservoirs created by Bonneville, The Dalles and John Day dams.

In response, the U.S. Army Corps of Engineers' Lisa Wright said the Corps was ready to implement the request.

The non-Indian commercial fishery in the lower Columbia River below Bonneville Dam began a short season on Aug. 20.

Whether it's tribal fisheries, the non-Indian commercial fishery, or many of the basin's sports fisheries, nearly all are constrained by this year's poor steelhead returns.

Wagner reported to TMT members that as of Aug. 30, steelhead runs are returning at about 30 percent of the decadal average.

Based on preseason and in-season monitoring, state and tribal fishery managers have taken actions to reduce harvest impacts on steelhead, said Washington Department of Fish and Wildlife's Dan Rawding at an Aug. 14 meeting of the Northwest Power and Conservation Council.

"Additional actions to reduce steelhead impacts may be needed," he said.

The U.S. v. Oregon Technical Advisory Committee, also meeting Aug. 14, downgraded the upriver steelhead return forecast. The season forecast for the combined A/B-Index steelhead return to Bonneville Dam is now 119,400 fish, including 41,500 unclipped, naturally spawning fish.

The 2008-2017 U.S. v Oregon Management Agreement, which is currently being renegotiated, spells out specific harvest management guidelines for fall Chinook, steelhead and coho.

Cumulative steelhead counts over Bonneville Dam were 75,539 on Aug. 30. Passage at Bonneville Dam, which occurs July through October, is typically 50-percent complete by Aug. 14.

The predicted returns over Bonneville would represent the lowest passage since 1943.

Sockeye, too, performed poorly this year. The annual passage over Bonneville Dam is virtually complete. This last week in August saw just 15 more sockeye cross the dam, bringing the 2017 total to almost 87,700, substantially below the 10-year average of 316,000.

A small portion of the Columbia Basin's sockeye returns is destined for the Sawtooth Valley in Idaho's Salmon River basin. As of Aug. 30, 227 of these endangered salmon have passed Lower Granite Dam on their way to both natural and hatchery locations.

The bright spot this fall may be the coho returns. The preseason forecast is for a run size of 319,300 coho, including 196,800 early stock and 122,500 late stock. If accurate, that would be 93 percent of the recent five-year average of 344,500 fish, according to the TAC.

However, the 2,545 coho counted through Aug. 31 amount to only about a third of the 10-year average.

At the Aug. 14 Council meeting, Rawding explained the difference in returns among the basin's salmon and steelhead runs.

These species have different temporal and spatial distribution in the ocean, he said which leads to different smolt-to-adult returns.

SARs were low for steelhead and sockeye out-migrants in 2015, he said.

The basin's sockeye run and portions of the steelhead run migrated to the Pacific in 2015 during an earlier-than-usual hot summer and during a low-water year making for less than optimal river conditions for young fish headed to the ocean.

Compounding this were conditions these juveniles found when they reached their marine habitats; an overly warm ocean, called the blob, which produced poor food sources for salmonids.

Some of the 2017 Chinook returns were also affected by poor ocean productivity.

Rawdling and Idaho Department of Fish and Game's Paul Kline noted that despite record and near-record air temperatures in August, salmon and steelhead mortalities are similar to last year and nothing like what happened in 2015.

Laura Berg
Smaller Columbia River Fish Returns Constrain Harvests; Blob Cited as Factor
Northwest Fishletter, September 5, 2017

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