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Unusual Late Spike of Fall Chinook
Restores Run Expectations

by Staff
Chinook Observer, October 12, 2010

COLUMBIA RIVER - "A very late spike" in the number of upriver fall Chinook climbing fish ladders at the lower Columbia River's Bonneville Dam has lifted the run right back on track to achieve preseason expectations.

Through Sunday, a total of 459,181 adult fish, of which more than 331,300 are "bright" stock, had been counted passing the dam on the way to spawning grounds and hatcheries in the mid-Columbia's Hanford Reach, Snake River, Deschutes River and elsewhere. The balance are tule fall Chinook, most of which are bound for Spring Creek National Fish Hatchery in the Bonneville Pool.

The preseason forecast was for a return of 483,300 fall Chinook up and over Bonneville, including 342,100 bright stocks and 141,100 tules.

The upriver fall Chinook return had appeared to peak at about its normal run timing in early September with the season's highest daily counts, ranging from 16,530 to 21,612, between Sept. 4-8. Then, the daily counts began to shrink as would be expected, hitting a low of 6,795 on Sept. 20.

But then the spike occurred with counts of 13,186, 11,920 and 14,749 on Sept. 23-25 to help pad the overall count.

The counts then began to shrink again. The count Wednesday was 1,248.

It is "really very unusual" that such a late uptick would occur, said the Oregon Department of Fish and Wildlife's Kathryn Kostow, who chairs the Technical Advisory Committee. TAC, made up of federal, state and tribal fishery officials, produces run-size forecasts both preseason and in-season.

When the run appeared to be in decline, the forecast had been reduced from preseason expectations of 319,200 URBs to the mouth of the Columbia to 279,900 adult fish in a Sept. 24 TAC forecast. But the surge in fish counts - which was dominated by upriver brights - brought a hike of the URB forecast to 326,600.

TAC also updated the summer steelhead forecast this week. The current estimate for upriver steelhead passage at Bonneville Dam includes 314,000 Group A stock (including 123,000 wild or unmarked hatchery fish) and 71,000 Group B fish (19,600 wild or unmarked). The new forecast is down somewhat from preseason expectations of 337,500 A and 99,100 B steelhead.

Upriver summer steelhead include hatchery and wild fish that pass Bonneville Dam during April through October of each year. Fish passing during July through October are categorized as Group A index or Group B index fish, based on fork length. The larger Group B steelhead primarily return to tributaries in the Salmon and Clearwater rivers in Idaho, while Group A steelhead return to tributaries throughout the Columbia and Snake river basins.

Fall fisheries are, for the most part, winding down. The Buoy 10 sport fishery at the river mouth is complete with a catch of 6,800 chinook and 8,000 hatchery coho salmon. The catch was well below preseason estimates of 12,500 chinook and 11,900 coho.

The fishery from Tongue Point just upstream of Astoria, Ore., and Bonneville Dam opened Aug. 1, though retention of Chinook was prohibited after Sept. 11 in the Columbia reaches from the mouth of the Lewis River downstream. Catch estimates in the lower river through Sept. 30 are 17,200 chinook and 1,200 coho from 106,540 angler trips.

The Columbia non-tribal commercial fleet caught an estimated 22,525 chinook and 472 coho during seven fishing periods in August on the mainstem downstream of Bonneville Dam. The September commercial fishery consisted of one 10-hour outing Sept. 22-23 with landings of 5,582 chinook and 642 coho.

The commercial fleet also caught 20,000 chinook and 54,300 coho in fall "select area" fisheries. That's is well above the preseason catch expectation of 12,000 chinook and 43,000 coho. Select areas are off-channel sites where young hatchery fish get their final rearing so that the y home in on those areas again when they return as adults. The commercial, and sport, fishers can target hatchery fish in the select areas where few wild, protected fish roam.

Unusual Late Spike of Fall Chinook Restores Run Expectations
Chinook Observer, October 12, 2010

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