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NW Fishletter #379, March 5, 2018

[10] ISAB Offers Recommendations For Upper Columbia Spring Chinook Recovery

Prompted by the slow recovery of naturally spawning spring Chinook salmon in the upper Columbia River Basin, the Independent Scientific Advisory Board conducted a 10-month review of recovery efforts in the Wenatchee, Entiat and Methow rivers.

The ISAB provided numerous recommendations in a 246-page report, released Feb. 9 and shared at the Feb. 13 Northwest Power and Conservation Council meeting.

Two ISAB members--Stan Gregory, professor emeritus of fisheries at Oregon State University, and Steve Schroder, retired fisheries consultant and research scientist at the Washington Department of Fish and Wildlife--offered to the Council an overview of their work. And while the ISAB report included several recommendations for fish managers in the upper Columbia, the scientists also commended the fish managers' efforts, methods and cooperation with the ISAB during the review.

Part of the report, and the discussion before the Council, focused on the extra challenges that upper Columbia spring Chinook salmon face compared with summer Chinook in the same region and with spring Chinook returning to the Snake River Basin.

The review was initiated by the ISAB's Administrative Oversight Panel, which asked the board to evaluate habitat assessment, research and monitoring, and prioritization and coordination of recovery actions fish managers have taken for these spring Chinook, listed as endangered in 1999. The scientists met with tribes, state and federal agencies, PUDs and local groups involved in salmon recovery.

Gregory told the Council that measuring the success of spring Chinook returning to the upper Columbia against those returning to the Snake River can be seen as an apples-to-apples comparison, "but if they're apples, they're different-sized apples." He noted that the upper Columbia area includes three subbasins totaling 2.3 million acres, compared with 26 subbasins covering 28 million acres in the Snake River drainage. Additionally, the Snake River is a rain-dominated basin, compared with largely snow or rain-on-snow precipitation in the upper Columbia.

According to the review, the Snake River populations are also more abundant, leading to their threatened status, compared with the more dire endangered listing for upper Columbia springs. With fewer numbers, an adverse event--such as a year when a high percentage of adults are taken by predators in the lower Columbia River--can pose an even greater risk for the upper Columbia populations than for the Snake populations, the report said. As an example, the review noted, in years when returning spring Chinook are low, their chances of finding mates on the spawning grounds are reduced.

Abundance of natural origin spring Chinook salmon in the upper Columbia River from 1960-2016. Courtesy ISAB

Gregory told the Council that, adjusting for size differences, most measures of abundance and productivity of spring Chinook, their habitat, their in-river survival and their smolt-to-adult ratios in the two regions are similar.

Schroder told the Council they also compared spring Chinook with summer Chinook in the upper Columbia. According to the review, summer Chinook have not always been predominant compared with springs in the upper Columbia. Yet from 1988 to 2016, an average of 1,241 natural origin spring Chinook returned to the Wenatchee, Entiat and Methow subbasins, while natural origin summer Chinook returned at an average of 12,572 per year.

Schroder said summer Chinook appear to have numerous survival advantages, largely due to the timing of their migration, both upstream and downstream. As juveniles, spring Chinook often miss out on voluntary spills at Columbia River dams, which generally come after most springs have headed downstream.

Spring Chinook also spend more time in rivers and streams, leaving them more prone to predation. As adults, they're more likely to encounter rougher waters, and spend more time in the lower Columbia River--more than a month--making them more vulnerable to predators. And as spawners, they contend with summer Chinooks, which show up in the streams later, and can "superimpose" their own redds on top of the springs' redds.

Finally, Schroder said, because they're so scarce, not many spring Chinook are used for hatchery broodstock, leaving the wild fish more prone to domestication from stray hatchery fish.

Listed as endangered in 1999, spring Chinook include three distinct populations in the upper Columbia--the Wenatchee, the Entiat and the Methow--as well as an extinct population in the Okanogan River. In 2007, the Upper Columbia Salmon Recovery Board and the National Marine Fisheries Service (now NOAA Fisheries) developed a recovery plan for both spring Chinook salmon and steelhead. Its goal is to "secure long-term persistence of viable populations of naturally produced spring Chinook and steelhead distributed across their native range."

According to the ISAB report, recovery must include viable numbers of fish, a low risk of extinction, fish distributed across their habitat and genetic diversity. Although major recovery after 10 years would be unlikely, the review said, the slow recovery after more than 300 habitat projects raises questions about the lack of improvements.

The review noted that by the time these fish were listed as endangered--and even before construction of some of the major dams on the Columbia River--upper Columbia runs had already declined greatly due to "overfishing, mining, logging, grazing, agriculture, water withdrawal, and growth of towns along the river." In addition, the construction of Grand Coulee Dam in 1939 "has compressed 1,140 miles of river used for anadromous migration to less than 677 miles."

A long history of hatcheries in the region contributed to the decline, the review said. Fish managers at the time collected some broodstock from the lower Columbia River, and those stocks were mixed with upriver stocks. "The history of human decimation of salmon populations, mixing of stocks, and hatchery practices likely weakened or homogenized the prehistoric adaptation of Chinook salmon to the local physical, environmental, and biological characteristics of the [upper Columbia River] basins," the review noted. It said that recent DNA study analyzing DNA from prehistoric and contemporary Chinook salmon found a greater loss of genetic diversity in upper Columbia stocks compared with those in the Snake River.

Gregory said the upper Columbia models are useful for ranking projects, but suggested that fish managers could better coordinate their efforts to develop a more cohesive process.

Recommendations in their review included providing an analysis on cost-effectiveness of proposed projects to determine priorities; giving high priority to projects that restore key ecological processes and resiliency to climate change; and developing a research, monitoring and evaluation plan that encompasses impacts of habitat, hatcheries, harvest and hydroelectric operations in spring Chinook throughout their life cycle.

Gregory added, "We do see the upper Columbia River program as a very strong program. They're using scientifically sound approaches," he said.

Fish managers were also eager to provide information, and to learn from the ISAB's review. "We see that as a sign of a very healthy program," he said. -K.C. Mehaffey

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NW Fishletter is produced by Energy NewsData.
Publisher/Editor-in-Chief: Mark Ohrenschall, Editor: K.C. Mehaffey
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