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NW Fishletter #274, May 6, 2010

[2] Columbia, Snake Sockeye Runs Riding High

Regional fish managers expect another good year for returning sockeye to the Upper Columbia and Snake rivers, hoping to continue a trend that started two years ago.

But some fish scientists, including the region's independent science panel (the Independent Scientific Advisory Board), wonder why these runs are performing relatively better than other regional sockeye stocks.

In a recent review of the feds' proposal to barge more spring chinook and steelhead out of the Snake, they said NMFS hadn't proven that ocean conditions were primarily responsible for the improvement in sockeye returns, rather than increased spill and less barging of fish from the lower Snake since 2006.

The science panel didn't think the feds had made much of a case for marine conditions because they didn't explain why other regional sockeye runs that went to sea in 2006 and 2007 performed so miserably. But a closer look at those runs shows that they may have had their own problems long before they ever reached the Gulf of Alaska.

There is no debate over one thing--the upward trend of Columbia Basin sockeye runs counter to recent returns from the Seattle area's Lake Washington and B.C.'s Fraser River, where last year's 11-million sockeye forecast evaporated by late summer. Only about 1.4 million actually returned, which has led to an official government inquiry to examine the causes for the disaster. A preliminary report is due Aug. 1.

Although the Columbia Basin runs are miniscule compared to their northern cousins, and are counted in the thousands and hundreds of fish instead of millions, their return rates are two or three times stronger than they were just a few years ago.

The big turnaround began in 2008, when more than 200,000 sockeye returned to the Columbia, and left fish managers in shock--they had expected only about a third of that.

Most of the sockeye headed up the Columbia, turned left at the Okanogan River, and made a beeline for B.C.'s Lake Osoyoos, while a smaller group returned to Lake Wenatchee.

Another 1,000 ESA-listed sockeye made it into the Snake, and about 650 were counted at the hatchery weir near Redfish Lake, Idaho.

That huge return reflected a large increase in smolt releases in 2006 and better ocean conditions, along with improved inriver migrating conditions, principally more spill at dams--though the jury is still out as to which factors are most important.

A 2009 NMFS analysis found a correlation between returns to the Columbia and Snake, which suggested that improved ocean conditions likely played a large role in the better returns to both rivers. But others, including the Fish Passage Center, pointed to more spill and less barging in the Snake as more likely responsible for the eye-popping returns to Redfish Lake.

The feds' memo from the Northwest Fisheries Science Center in Seattle said that sockeye return rates from 1996 to 2008 correlated weakly with the ocean indicators developed by the agency, but they also noted that those indicators didn't include the food resources important for young sockeye.

To make things even more confusing, they said the added spill at lower Snake dams did correlate with Snake sockeye returns, but the Columbia returns showed a negative correlation with spill at dams along their migration route.

Last year, the Redfish Lake sockeye return was even better--about 700 made the 900-mile trip back from the ocean out of 1,200 that were counted at the halfway point on their journey--Lower Granite Dam.

This year, managers have tentatively estimated that about 600 are expected to make it back to the mouth of the Columbia. But that's about what they predicted to return the year before. Idaho Fish and Game personnel think the run will be better than that. They reported recently that their 2010 Redfish Lake sockeye estimate ranges between 700 and 1,100 fish getting back to Lower Granite Dam.

In early 2008, the technical managers estimated only 700 Snake sockeye would return later that year, but the actual return was over a thousand fish. The Upper Columbia run was forecast at 75,000, but actually came in around 215,000.

Last year, they predicted 600 Redfish Lake sockeye to return to the Columbia mouth, and the final tally ended up more than twice that. However, the Upper-C run came in close to the 183,000-fish prediction.

Two years ago, Canadian biologist Kim Hyatt told NW Fishletter that, given the nearly 1.5 million smolts leaving the B.C. lake in 2008, he expected a really big return this year, since ocean conditions were prime when the juvenile fish reached the ocean.

Since then, managers have become more circumspect about this year's Upper C run, which is now expected to be about half the size of 2008's record-breaker, the largest sockeye return to the Columbia since 1959.

With this year's low flows, federal agencies were prepared to shut down all spill at collector dams and barge as many spring chinook, steelhead and sockeye as possible during May, but they decided to abandon the strategy after the ISAB's review and a subsequent meeting with other sovereigns to discuss the issue.

The review pointed out that survival data is lacking to determine whether barging helps sockeye, and there is some evidence that sockeye descale more easily than chinook or steelhead in bypass systems at dams--a route they must take before they are delivered to barges. Descaling can lead to early mortality.

But the ISAB also said NMFS couldn't really say that improvement in marine conditions, rather than the extra spill at dams since 2006, has benefited the Columbia and Snake sockeye runs.

They said the feds offered no hypothesis with supporting empirical evidence "to explain how or why marine climate has been favorable to sockeye smolts, in contrast to the hypotheses about conditions that favor inriver survival."

The ISAB said any such marine hypothesis would have to explain why ocean conditions in 2006 and 2007 "have been unfavorable to sockeye smolts from other geographically proximate populations whose SARs have also been measured (Lake Washington in Puget Sound, Chilko and Cultus lakes in the Fraser River, Sakinaw Lake in Georgia Strait). Given this uncertainty, it seems transportation of sockeye smolts adversely affects their survival."

But a closer look at the other sockeye stocks mentioned by the ISAB shows that their ultimate survival may have depended more on how well they coped with conditions closer to home, long before they reach the open ocean.

A recent report from the Washington Department of Fisheries suggested that the biggest bottleneck to sockeye survival for the Cedar River run may occur in Lake Washington, itself, when emerging fry compete with other lake species like smelt and stickleback for food, long before they ever reach salt water.

The report says productivity of the Cedar River stock is far lower than eight reference stocks from Washington and southern British Columbia. More fry in the lake means less fry-to-adult survival.

As for Fraser sockeye, there is evidence that early salt-water mortality may have killed most of the 2007 Fraser and Sakinaw sockeye smolts in Georgia Strait before they even reached the open ocean north of Vancouver Island.

Canadian federal fisheries scientist Dick Beamish told NW Fishletter that his annual smolt survey in the Strait showed up few Fraser smolts in 2007, which indicated to him the likelihood of an adult return well short of the 11-million fish prediction. What might have caused the high mortality?

Beamish, who works out of the Department of Fisheries and Oceans' Pacific Biological Station in Nanaimo, B.C., said waters in the Strait are warmer than in previous decades, and likely have an important role in juvenile salmon survival.

Since the mid-1990s, he said, coho, chinook and sockeye runs that use the Strait as a migration corridor have tended to decline, while pink and chum stocks have trended upward.

In 2007, many sockeye smolts in Georgia Strait may not have grown fast enough in the warm water due to metabolic issues, may have become weak, and later succumbed to a variety of natural diseases, Beamish said.

And in even-numbered years, when juvenile pink populations are relatively large, they may be competing with other salmon species for food--a condition where the carrying capacity of the system could be overwhelmed. The pinks stick around until September, while most sockeye are directed migrators, and head north much sooner.

One note of optimism here is that Beamish' annual smolt survey turned up high numbers of young sockeye in 2008 and 2009. So, the huge number of Fraser pinks that went to sea in 2008 (returned in 2009) may not have swamped the sockeye, who spend two years at sea, and are slated to return this year.

One draft estimate from DFO has placed a 50-percent probability of an 11-million-fish return this year. Beamish said his smolt survey suggested about a 10-million fish return.

And the huge Fraser pink run that returned in 2009 may have been even larger than most officials think. The Pacific Salmon Commission pegged it at an astonishing 21 million fish. But that may have been a lowball estimate, said Brian Riddell, executive director of the Vancouver-based Pacific Salmon Foundation, and an ex-ISAB member himself.

Riddell said there is evidence that the run was far stronger, about 30 million fish overall. That would put it far above the two largest returns (more than 20 million in 1991 and 2001) since 1959, when biologists began keeping track.

Meanwhile, back in the Columbia, things are looking up as well.


South end of Lake Osoyoos and associated plumbing.
-courtesy COBTWG

Howie Wright, a tribal biologist with the Okanagan Nation Alliance--which is working with other groups to boost the Lake Osoyoos sockeye stock--shared some amazing news last week.

Thanks to a shot of fresh water released into the lake last September to counteract low-oxygen levels, Wright said, it seems that fry production has gone through the roof. He expects around 8 million smolts to leave the lake this year. That's five or six times the number that migrated out two years ago.

But with inriver migration conditions fairly poor this year, it is not clear how many juveniles will make it to the ocean. However, the NMFS 2008 sockeye review reported that Upper Columbia juveniles experienced relatively high survival (66 percent) between Rock Island and McNary dams in 2001, when flows were the second worst in the past 50 years.

This year, flows are expected to be third worst, while conditions in the ocean itself are expected to be improving from the El Niño situation that developed last year. -B. R.

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