the film
Commentaries and editorials

Biologists Wonder Why
Wild Salmon Numbers are Down

by Staff
The Idaho Statesman, August 23, 2003

Birds do it. Bees do it.

Now, a group of scientists wants to find out why Pacific salmon don´t do it — at least, as well as they could — leaving some on the brink of extinction.

The Cooperative Institute for Salmon Research and Science — recently formed among scientists from the University of Idaho, Washington State University and the National Marine Fisheries Service — will look at basic biological problems that could be causing dwindling populations of wild salmon.

“Hopefully, within five years, we will have identified the problem and suggested a potential solution,” said Michael Skinner, director of the WSU Center for Reproductive Biology who heads the salmon institute.

The bulk of salmon research has involved improving habitat and hatcheries, Skinner contends. Less attention has been paid to the basic biology and environmental effects on the fishes´ genetics and ability to successfully reproduce.

Skinner compares the situation with salmon to that of the bald eagle.

In the 1960s, large tracts of land were restricted to help the bald eagle before the discovery that a commonly used agricultural chemical, DDT, caused thinning of the birds´ eggs and poor reproduction, Skinner said. When the chemical´s use was restricted, the birds made a comeback.

Studies of salmon biology may find a similar environmental toxin, Skinner said.

For instance, the puzzling issue of salmon born genetically male that become egg-laying females may be linked to estrogen from human birth control pills that makes its way through sewage treatment plants, Skinner contends.

“We think it is probably in the very early embryonic stage … possibly environmental toxins,” Skinner said.

Scientists have found sex-reversal in some salmon populations on the Columbia and Yakima rivers in Washington state, as well as some in northern California, Skinner said.

“This is about the biology of salmon and how they relate to risks posed by the environment,” said John Stein, director of the Northwest Fisheries Science Center of the National Marine Fisheries Service in Seattle.

“We´ve been doing a lot of work about habitat and climate change, but biology needs to be part of the continued efforts,” he said. “This is all about how fish respond to the changes.”

Among the 15 research projects the institute will conduct are molecular and genetic comparisons of hatchery-raised and wild fish; an assessment of the effects of genetic damage on reproduction; and development of a “gene bank” where genetic materials from threatened salmon populations would be cryogenically frozen.

In recent decades, fisheries managers worried that hatchery successes may have come at the expense of wild stocks.

They have stressed the need for a better balance between wild salmon that spawn in the headwaters of mountain streams and lakes and those produced in plastic buckets at hatcheries.

Bill Bakke, president of the Native Fish Society of Portland, Ore., a critic of hatchery programs and policies, said the institute´s research is driven by hatcheries.

“Domestication selection fouls up the works. When they interbreed with wild salmon, it lowers wild production,” he said.

Skinner agreed, saying the rationale for pushing hatchery-reared salmon was that numbers of returning salmon dropped to historic lows in the mid-1990s, and there were too few wild salmon to study.

Subsequently, large numbers of fish have returned, including about 20 percent wild stocks, allowing more study of the wild fish, he said.

Biologists Wonder Why Wild Salmon Numbers are Down
The Idaho Statesman, August 23, 2003

See what you can learn

learn more on topics covered in the film
see the video
read the script
learn the songs
discussion forum
salmon animation