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CORVALLIS, Ore. - Steelhead are spawning in the new artificial stream channels at the Oregon Hatchery Research Center in the Alsea River basin, and researchers have begun studying how the fish choose mates and where they prefer to spawn - key factors in preserving fish runs.

But it is the future of scientific inquiry that has fish researchers excited about this new facility, which is jointly operated by the Oregon Department of Fish and Wildlife and Oregon State University's Department of Fisheries and Wildlife.

And part of that excitement is focused on a single word: isotopes.

Fish have a bony structure within their ears called an otolith, which accretes calcium carbonate. By examining the isotopes within the otolith, they can amass critical new data about the age of fish, where they have lived and what they have eaten, said David L.G. Noakes, a professor of fisheries in OSU's College of Agricultural Sciences and senior scientist at the Oregon Hatchery Research Center.

"These otoliths are like flight recorders," Noakes said. "They're swimming recorders in fish."

Noakes said that a high ratio of strontium-to-calcium isotopes, for example, indicates that a fish has been living in the ocean, while a lower ratio suggests a recent freshwater history. These isotopic signatures may eventually be refined enough to pinpoint how long fish have been in freshwater, at what depth in the ocean they swam, and what types of prey they ate while at sea - all critical to gaining a better understanding for how to protect different species.

"It's even more precise on smaller fish," Noakes pointed out. "We should literally be able to examine a fish and say that it is 112 days old, it left the hatchery on day 37, it entered the Alsea River on this certain day, and stayed in freshwater for this period of time."

Noakes said the isotope research can be extended to predators of salmon and steelhead, or to scavengers that eat the fish that die after spawning, or are dumped back in the water by fishermen or biologists seeking to return nutrients to the river.

"In theory," he said, "we should be able to use the feather of a bird or the hair of a bear to pinpoint the different isotopic signature that will tell us what they ate and when they ate it."

The isotope research is just one of many fascinating areas of inquiry envisioned by researchers at the new $8 million center, which opened in October. Noakes, who has forged a reputation as one of the world's premier fish biologists and ecologists, came to OSU from the University of Guelph in Ontario.

Upon Noakes' arrival, then ODFW Director Lindsay Ball said that he would "be an effective leader putting Oregon back on the front line of fishery science and research."

That research agenda hasn't fully been set yet and may depend on funding from state and federal agencies, foundations, the fishing industry and related businesses, and private gifts. Yet Noakes said the potential of the new facility is vast.

"One of the areas we want to explore stems from an eastern controversy about Atlantic salmon," Noakes said. "And that is to look at the question: 'Are hatchery fish competent?' Some folks say they are pellet hogs that do nothing but eat and when you put them in the wild, they roll over and play dead. Others say that hatchery fish are the source of all evil, that they take over and crowd out wild fish. And many others see hatcheries as the only realistic option for supplementing and conserving fish species.

"We can use the facility, with its artificial streams, to look at these issues," he added. "We can see if hatchery fish will spawn with wild fish, or if they will crowd them out of spawning beds. We can compare juvenile growth rates and survival. We can see how wild fish and hatchery fish compete."

Noakes said the research center has received 5,000 juvenile steelhead, about three to four inches in length, and they will use the facility's tanks to conduct a number of tests - raising them in different "family" groups, in large and small tanks, and in different numbers in an attempt to discover optimum rearing conditions. The fish also will be fed different diets and raised in different water temperatures.

The researchers also are looking for new ways to control disease. Young salmon and steelhead, particularly those raised in hatcheries, are susceptible to a variety of bacterial and fungal infections. Traditional ways of treating the water in rearing ponds have used diluted forms of formaldehyde, which has environmental drawbacks. Noakes said the researchers will use ultraviolet light to sterilize the water.

"We know it works in theory," Noakes said, "but we have to be able to show that we can turn out healthy fish using that method."

Also on tap is a plan to experiment with the fish diets - not just for purposes of creating healthier fish, but for marking them with a chemical tag. A diet rich in sulphur, for example, provides an isotopic signature that lasts forever, Noakes said. Otolith examination of fish returning from the ocean three years later will carry that signature, lessening the need for other, more invasive tags.

As the science agenda develops, Noakes said he wants to make sure that the process is interdisciplinary and far-ranging. He recently invited to the center a dozen scientists whose background does not include fish - forest engineers, stream ecologists, hydrologists and entomologists - to brainstorm ways to make the Oregon Hatchery Research Center as productive and far-reaching as possible.

"This is a unique facility and these are complex issues," Noakes said. "It pays to listen to everyone."