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NOAA Developing Tools to Match Ocean Conditions, Fish Runs
June 16, 2006

The near edge of that "black box" called the Pacific Ocean has been pried open by NOAA Fisheries scientists who say they can gauge how well juvenile salmon and steelhead survive during that crucial time when they move from Columbia River freshwater to saltwater.


Fish managers, Columbia River basin policymakers and others point to the dynamic Pacific Ocean as a cause of wide variations in salmon returns from year to year. But little is known about what causes those changes other than effects from shifting water temperature and availability of food resources for the salmon.


NOAA scientists have, however, since 1998 been trying to learn how each of numerous changing physical and biological indicators in the Northern California Current ecosystem affect juvenile salmon survival. They expect the work will soon provide an additional tool for predicting, based on those survival estimates, the size of the returns the following year or two.


The work attempts a "deconstruction of what people call the black box in the ocean," according to John Ferguson, director of the Fish Ecology Division at NOAA's Northwest Fisheries Science Center in Seattle. The ocean is hard to study, and impossible for man to manipulate. It remains largely a deep and mysterious place where conditions can change drastically, from day to day, and from decade to decade.


"The variability in freshwater is slight compared to the variability in saltwater," Ferguson said of the conditions salmon face throughout their life cycle.


The California Current is the flow that surges east from mid-ocean and hugs the southern British Columbia, Washington and Oregon coasts as it continues southward. Its temperature can change up and down. A pattern called the Pacific Decadal Oscillation shifts from positive to negative in terms of how it affects salmon production.


Changes occur too in ocean productivity -- the amount of animal and plant life it provides. That affects salmon maturation and survival. And it affects the survival of fish that prey on salmon.


NOAA's Northwest Science Center has been monitoring the coastal ocean environment off Washington and Oregon, including an assessment of the Columbia River plume, its interaction with the California Current and how it affects the abundance, distribution and growth of juvenile salmon as a means to assess their survival as they enter the marine landscape.


Physical and biological features have been assessed over time frames to evaluate how each might affect survival. The resulting indicators can be tabulated to estimate how the young fish might fare in any given year.


Marine survival is very important. NOAA estimates that an increase in survival of from 1 to 2 percent would double the size of the adult return to freshwater.


Current salmon return forecasts are based in large part on the number of "jacks" and other age-classes that return the previous year. Jacks are salmon that return prematurely, before they are old enough to spawn. Fisheries experts estimate what share of a brood year's output that the jacks represent. Their broodmates return in subsequent years to spawn.


NOAA's indicator assessments will in June and September be able to predict how many jacks might return the next year based on the conditions the smolts faced in the plume and near-ocean environment.


"By June we can have a pretty good idea of the physical condition of the ocean" and how salmon might respond to those conditions, Ferguson said. By September, biological conditions such as food availability and predator population status can be added in to the equation.


As an example, 2007 chinook salmon returns, and this year's coho run, are expected to be down from those of the recent past. Jack counts so far this year have been lower than those of recent years that foretold higher than average adult returns.


"Indicators predominately turn bad in 2005" and have stayed that way, Ferguson told the Northwest Power and Conservation Council during a Wednesday progress report on NOAA's findings. The PDO, ocean upwelling of nutrients and predator abundance and other indicators are less unfavorable for juvenile salmon growth and survival during the period following ocean entry -- the early summer and fall.


The Columbia River plume -- a freshwater/saltwater solution where the young fish can steady themselves before venturing off into the ocean -- can vary from day to day, growing or shrinking, drifting north or south, changing shape. The plume is whipped by the wind, and changed by the quantity of outflow from the Columbia. The latter can be manipulated to some degree by Columbia hydro operations.


NOAA had linked the size of the plume to the size of the steelhead return, generally larger the plume upon the juveniles entry, the larger the return of that brood class.


"It's very important for yearling fish," said Ed Casillas, manager of the center's Estuarine and Ocean Ecology Program.


NOAA's next step is to put the information in a format that will be readily available to management entities. The agency plans to evaluate the indicators annually and communicate the status of the Northern Californian Current Ecosystem annually through a technical report, as well as post the information in "real time" on the agency's web site for fishery managers to use.


The forecasts should help managers make decisions -- such as setting harvest targets, adjusting hatchery production during periods of poor ocean productivity and placing more or less emphasis on hydropower prescriptions and freshwater restoration activities depending on ocean productivity.


The assessments should help in "getting the right number of fish to the ocean at the right time," Ferguson said.


"Our scientists are about to complete important research on the huge influence that changing ocean conditions have on salmon from the time they migrate as juveniles through the estuary into the ocean to when they return as adults," NOAA's regional administrator, Bob Lohn said of the project.


"This ongoing research will help future salmon management decisions," he added.


In a press release issued Thursday, Lohn noted that the 2006 upriver spring chinook return was higher than the 10-year average.


"The long-term average continues to rise," Lohn said. "I'm convinced that efforts we've made to improve fish passage through the dams, significant investments to enhance fish habitat, and our current hatchery and harvest management reforms will help salmon recover for the long term."


Those improved in-river conditions do not always translate into larger runs because the ocean's large role.


"The poor ocean conditions we observed in 2004 and 2005 lead us to expect lower rates of return for spring Chinook in 2007," Lohn said. "The counts of jacks the early-returning fish from the juveniles that migrated to the ocean in 2004 and 2005 are about two-thirds of last year's number."




Page Updated: Thursday May 07, 2009 09:14 AM  Pacific

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