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NW Fishletter #314, March 7, 2013

[1] Ocean Workshop Looks For New Ways To Use Research

A day-long Feb. 14 workshop that reviewed the latest research on salmon and ocean conditions showed just how much the success of recovery actions depends on factors outside our control.

Sponsored by the Northwest Power and Conservation Council, the workshop brought together ocean researchers and freshwater fish managers to kickstart the council's update of the 2009 ocean research plan. It's part of the upcoming amendment process to the region's fish and wildlife program, largely underwritten by BPA.

The researchers touched on several topics of importance that are rarely acknowledged in these public forums. These include the possibility that regional hatchery production mandated by treaties and dam mitigation may be undermining recovery efforts of ESA-listed stocks in the Columbia Basin, and whether we are releasing too many hatchery fish, especially in years when conditions in the salt water are relatively poor.

Also discussed was whether the region's growing knowledge of ocean effects on migrating salmonids can be used to improve survival, and whether we can we regulate flows to improve fish conditions in the estuary and plume offshore.

The survival of the ocean research funding is itself at stake, since BPA budget bean counters are ready to pencil out the several million dollars in annual costs. They say it doesn't mesh with their basic focus on the hydro system.

But the independent science panel that reviewed the ocean research program feels differently. ISAB member Kate Myers, from the University of Washington, an ocean researcher herself, explained the draft recommendations to reprioritize ocean research strategies.

Myers said the first priority is "to understand and isolate effects of ocean conditions on anadromous fish survival and growth to increase the power of analyses to detect the effects of restoration actions in the Basin."

The second priority is "to determine limits to restoration potential or the effectiveness of actions taken in the Basin given the variability of ocean conditions that affect anadromous fishes."

The third priority "is to predict future ocean conditions with a view to adjusting actions in the basin to achieve greater benefits and/or efficiencies."

"In essence, the ocean conditions are the big wheel that's driving the survival and growth, and ultimately, the restoration actions in the basin," she said.

"Sometimes," Meyers said, "ocean conditions are going to be such an overwhelmingly important driver of productivity that no matter how much work you do on habitat restoration or how many hatchery fish you release into the ocean, you're still not going to get any improvements."

She pointed out that extensive research has shown that "salmonids in pristine populations where there's never been any damage to the habitat at all, and even under perfect, pristine habitat conditions during periods of poor climate and ocean conditions, the abundance and productivity of the populations is going to be low."

Myers called for the coordination of ocean strategies across all ecosystems.

"Ocean research, as we know, is very expensive, and there's also going to be a need to coordinate with entities outside of the Columbia River Basin who are already conducting ocean research, both international and national entities, and perhaps foundations as well," she said.

Antonio Baptista, director of the Science & Technology Center for Coastal Margin Observation & Prediction at Oregon Health & Science University, said enough data has been collected about the freshwater plume and estuary to predict future conditions. River discharge is the most important factor governing the size of the plume, with prevailing winds second, he said. The region now has the potential to manage the river discharges, to make in-season and long-term adjustments in how we manage fish and the ecosystem at large to affect the success of recovery efforts.

NOAA Fisheries scientist Richard Brodeur described predator-prey interactions with juvenile salmonids in the river plume, noting that different juvenile salmon populations, rearing types, and species overlap in distribution and diet at sea. He said there is evidence that large releases of hatchery salmon may compete with wild salmon, especially when ocean conditions are poor.

Though juvenile salmon are only minor constituents of the shelf communities in the California Current, Brodeur said food web interactions must be considered to understand variation in salmon production and survival. When jellyfish are abundant, he said, young salmon feed less. When other forage fish are abundant like smelt, sardines, herring, or anchovies, schools of predatory fish like hake and mackerel eat fewer juvenile salmon. He said predation rates on salmon are difficult to quantify, but are likely important to survival and may be related to availability of alternative prey.

Brodeur also pointed out evidence that Chinook are competing with other salmon species. In a 2004 study of Puget Sound Chinook, he noted that the Sound's Chinook survival was 62 percent lower when migrating in even-numbered years when juvenile pink numbers are high. Such survival differences are not found off the Washington coast, however, since there are few to no pinks.

Brian Beckman, a NOAA Fisheries scientist from Seattle, reported on recent results from his group's work on marine survival of hatchery fish. Beckman said the agency is trying to determine if density dependence is occurring in the estuary and ocean plume. If it is, then increased competition for food could mean slower growth for juveniles, and ultimately lower survival.

Since growth is different from year to year, Beckman said there is competition for food, but he also noted that "not all hatchery fish are equivalent." Hatchery spring Chinook are released at different times throughout the basin, he said. Some, like those from the Willamette, are released as early as February. The young fish reach the ocean at different times and are of different sizes, but by June most have headed north; there is a three-fold decrease in spring Chinook smolt abundance from May.

Beckman said Willamette hatchery spring Chinook smolts are actually twice the size of smolts from the Snake, and make up most of the smolt biomass in May trawl surveys. Their size and abundance means the food requirements for the Willamette fish are double those of any other group of smolts.

He said little data is available on wild smolts, but some management options are available that might improve survival. Food demands for some stocks could be lowered by changing abundance and mean size of hatchery releases by stock; or the spatial and temporal overlap of different stocks might be reduced by changing release timing; and river management options for spill, barging, and spillway weirs could be considered to increase or decrease the spatial and temporal overlap of different stocks.

NOAA scientist Rich Zabel reported on some management implications of his agency's research as it develops a life-cycle survival model for different ESA-listed stocks. This work has shown the best time to transport smolts out of the Snake, and they have been modeling smolt-to-adult return rates for upper Columbia Chinook under various river scenarios being studied by groups involved in the review process of the Columbia River Treaty with Canada.

Use of the growing data sets of biological and climatic observations collected by ocean researchers in recent years was discussed by NOAA researcher Brian Burke. He said it was important to develop a mechanistic understanding of the factors that really matter.

Burke presented a rather humbling slide that mapped the relative correlation of different factors, including PDO, upwelling, ocean temperatures, forage fish, and river flows to fish survival, clear back to the early 1960's, which showed no single factor was important in every decade, and some, like river flows, didn't seem important at all. But Burke's comments were cautionary: "Correlation is not causation."

He also noted that many stocks are in different places at different times, so they are likely most affected by different factors, which also fluctuate throughout the year. For instance, his preliminary findings showed that survival of A-run steelhead, fish that return after only one year at sea, is mostly correlated with levels of wintertime fish eggs and larvae in the near ocean and PDO, but least with river flows, while B-run steelhead returns were highly correlated with the Jan.-June Oceanic Niño Index and river flows.

Differences were also evident when he compared preliminary findings from hatchery spring Chinook from the Imnaha River and wild John Day spring Chinook. The Imnaha stock's survival seemed mostly correlated with the Jan.-June Oceanic Niño Index, and various indicators of available food, while survival of wild John Day fish mostly correlated with different feed indicators, and early spring transition. But the survival of each stock, one which travels to the ocean all the way from the lower Snake, and the other, which passes only two dams before it reaches the estuary, correlated not at all with Columbia River flows.

Burke said future preseason forecasts based on his group's work might eventually help managers make decisions over harvest, egg-take, escapement, and run-timing diversity.

Some regional fish managers in attendance were appreciative of the recent findings, but expressed doubts about the ability to time hatchery releases for improved survival. One said holding hatchery fish back might actually reduce their survival. Others said the lack of correlation between river flows and adult survival did not reflect results from their own analyses.

A recent peer-reviewed paper that explained the NOAA fish forecasting tool said that indicators representing the Columbia River environment ranked near the bottom in relative importance of the 31 different factors they used to generate their spring Chinook predictions. -Bill Rudolph

The following links were mentioned in this story:

workshop

recent peer-reviewed paper

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