OREGON STATE UNIVERSITY

How do hatchery and wild salmon and steelhead interact?

05/14/2012

CORVALLIS, Ore. – Genetic differences between hatchery-raised salmon and steelhead and fish born in the wild have sparked controversy and raised questions about future policies, overshadowing ecological interactions that may ultimately be of greater importance.

How hatchery and wild fish deal with competition, predation, disease and ecosystem effects will dictate fish runs of the future, yet the science on salmon has lagged behind management decisions.

That may be changing. The professional journal Environmental Biology of Fishes is publishing a special edition this May called “Ecological Interactions of Hatchery and Wild Salmon” that provides some of the latest findings on the topic. Edited by David Noakes of Oregon State University, the journal will include results from 22 studies conducted by scientists around the world.

The papers were presented at a conference organized by the Wild Salmon Center in Portland.

“Before we address whether we can have both wild fish and hatchery fish,” Noakes said, “we need to design a platform of scientifically based research to answer a series of questions. And we need to carefully define just what those questions are. People are always looking for simple solutions, and they are usually driven by short-term needs.

“But managing salmon, which live in both fresh and salt water, and may migrate through waters of multiple jurisdictions, is quite complex,” Noakes added. “When you add in variables such as habitat loss and ocean conditions, you also have to look at long-term trends.”

Noakes is an internationally known fish biologist who came to OSU in 2005 as professor and senior scientist with the Oregon Hatchery Research Center, a facility in the Alsea River basin jointly operated by the Department of Fisheries and Wildlife at OSU and the Oregon Department of Fish and Wildlife. Here scientists study fish ecology and behavior in artificial streams as well as in Fall Creek and Alsea River.

If hatcheries are part of the solution for stable fish runs of the future, some of the changes they will need to make may emerge out of research at the facility. But, Noakes cautions, seemingly simple changes can have multiple impacts – not all of them positive.

“You often hear people say that we should create more fish,” Noakes said. “But if our hatcheries produce more smolts, do we know that more fish will come back as adults? When we push fish out of the hatcheries at certain times of the year, we create a big flush of food for hawks, cormorants, seals, fox and numerous other predators. If you drop a bunch of candy in the street, kids will show up to eat it.

“The wild fish may get hammered along with the hatchery fish,” Noakes added. “We may actually be doing more harm than good.”

Such reasoning is why Noakes said a thoughtful, well-designed research agenda is so critical. Hatcheries produce a staggering 5 billion salmon and steelhead each year, and both Alaska and Russia are planning to increase that number. While the ocean is a vast area, salmon tend to congregate in certain areas and thus may compete for food and habitat.

Before churning out more and more hatchery fish each year, scientists need to better understand foraging and breeding competition with wild fish; influence of disease and parasites; constraints by habitat in fresh water and marine environments; growth and survival rates; influence of predation; and freshwater and saltwater life cycles and the timing of migration.

“Many of the studies illuminate our understanding of hatcheries as a potential and growing risk factor to wild salmon throughout the North Pacific,” said Pete Rand, senior conservation biologist with the Wild Salmon Center. “Much of the research and media attention has focused on hatchery impacts of ‘stream type’ salmon and steelhead; some of the new studies more fully explore potential effects of hatcheries on ‘ocean type’ salmon, such as chum and pink.”

Some important studies are beginning to emerge that will answer some of the questions and help define the future research agenda, Noakes said. The forthcoming special edition of Environmental Biology of Fishes includes a range of studies. They include:

  • Barry Berejikian, of NOAA’s Northwest Fisheries Science Center in Washington, and colleagues found that rearing hatchery steelhead for two years, instead of breeding them to grow quickly and releasing them as yearlings, more closely mimics behavior of wild steelhead and could improve survival rates of hatchery fish;
  • A literature review by Seth Naman, of the National Marine Fisheries Service, found that predation of wild juvenile salmonids by hatchery fish overall was low, but increased greatly if the timing of the hatchery release coincided with large numbers of wild fish still in the river;
  • An article by W. Stewart Grant, of the Alaska Department of Fish and Game, outlines the case for preserving in wild fish populations their “adaptive potential” to environmental conditions as a buffer against disease and climate variability – and suggests considering adaptation  in planning hatchery production levels and release timing and locations;
  • A study led by Gregory Ruggerone, Natural Resources Consultants, Inc., suggests that the release of hatchery chum salmon from Asia resulted in a dramatic decline of a small wild chum salmon population in western Alaska.

“The impacts of hatchery fish are just one of many risk factors fisheries managers must account for in ensuring wild fish are conserved and recovered for present and future generations of Oregonians,” said Bruce McIntosh, ODFW’s deputy administrator for inland fisheries.

McIntosh said ODFW actively supports research addressing the underlying mechanisms that cause the differences between hatchery and wild fish, and management solutions to minimize the risks of hatchery fish.  “That fundamental question is why the department worked with OSU to develop and fund the Oregon Hatchery Research Center,” he pointed out.

The articles are available at: http://www.stateofthesalmon.org/hatcheries/abstracts.html