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Forecast Predicts Higher Upriver Steelhead Numbers Than Last Year

by Staff
Columbia Basin Bulletin, March 29, 2013

339,200 Fish Expected

After an unexpected off year in 2012, fisheries experts predict that the 2013 Columbia-Snake "upriver" summer steelhead run will rise again nearer to levels enjoyed by anglers during the previous 12 years.

In a forecast released March 17 the Technical Advisory Committee predicts that 339,200 adult upriver steelhead will return to the Columbia and climb over Bonneville Dam on their way to hatcheries and spawning grounds in Idaho, Oregon and Washington.

The total return to Bonneville Dam (April-October passage) of upriver summer steelhead in 2012 was only 230,800 fish, which was 61 percent of the preseason forecast of 380,300 upriver steelhead and the lowest return since 1999, according to the Jan. 24 "Joint Staff Report" produced by the Oregon and Washington departments of fish and wildlife.

The 2012 return was 60 percent of the recent 10-year average return of 383,700 fish. Actual returns since 1999 have ranged from a record high 630,230 in 2001 to 308,161 in 2004. The 1999 run numbered only 184,368 upriver summer steelhead.

Upriver summer steelhead returns to Bonneville Dam have been relatively stable since at least 1984. During 1984-2011 Bonneville Dam passage has ranged from 160,800 fish up to that 2001 high mark with an average of 314,600 upriver summer steelhead.

The 2013 forecast includes the projection of 16,600 "upriver Skamania index" steelhead, including 5,300 "wild" fish. The 2012 Skamania return totaled 10,900, including 3,000 wild fish.

Summer steelhead passing Bonneville Dam between April 1 and June 30 are managed as Skamania stock steelhead primarily destined for tributaries within Bonneville Pool, according to the staff report. Summer steelhead passing Bonneville Dam between July 1 and October 31 are considered to be either Group A or Group B stock.

Group A steelhead are destined for tributaries throughout the Columbia and Snake basins, are characteristically smaller (less than 78 cm length) and spend one or two years at sea. Group B steelhead return to the Clearwater and Salmon rivers in Idaho, are generally larger (at least 78 cm length), later-timed than the Group A steelhead, and typically spend two or three years at sea, the staff report says.

The upriver summer steelhead includes three separate species -- "designated population segments" -- that are protected under the federal Endangered Species Act. And while hatchery fish are included in those designations, fisheries management is particularly guided by limits on the take of unmarked, potentially wild, steelhead. Most hatchery produced fish are marked with a clipped adipose fin.

NOAA Fisheries has divided the upriver wild summer steelhead run into three DPSs: 1) the middle Columbia DPS which includes steelhead destined for Columbia River tributaries from upstream of the Wind and Hood rivers upstream to and including the Yakima River (listed as threatened in May 1999), 2) the upper Columbia DPS which includes steelhead destined for Columbia River tributaries upstream of the Yakima River (listed as endangered in May, 1999), and 3) the Snake River DPS which includes steelhead returning to the Snake River basin (listed as threatened in October 1997).

The bulk of almost any year's upriver return is the A run. The new TAC forecast predicts that this year's run will include 291,000 A fish, up from 192,200 last year. That run is expected to include 83,500 wild fish; the total last year was 55,500.

The B run is predicted to include 31,600 fish, up from 27,700 last year. An estimated 7,900 wild fish is expected in the B run this year (6,800 in 2012).

The majority of steelhead passage at Bonneville Dam, located at river mile 146, occurs during July through October. During these months in 2012, a total of 219,857 steelhead passed Bonneville Dam, compared to the recent ten-year average of 367,700 fish and the expected total passage of 364,600. Passage was 50 percent complete on Aug. 10, compared to the average 50 percent date of Aug. 15.

Typically peak counts occur during roughly the last week of July and the first few weeks of August, but the 2012 counts were minimal during this time frame when compared to past years. Preliminary analysis suggest that the 1-salt component of the Group A return did not return at the proportion typically expected, which may be an indicator of poor ocean conditions upon entry for the 2010 brood.

Forecast Predicts Higher Upriver Steelhead Numbers Than Last Year; 339,200 Fish Expected
Columbia Basin Bulletin, March 29, 2013

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