WASHINGTON 4/9/02 -- The U.S. Fish and Wildlife Service is wrestling with a sexy little question. Should it protect a fish when it may be mating itself out of existence?

The westslope cutthroat trout, which was plentiful in western waters when Lewis and Clark made their expedition, has been interbreeding with rainbow trout that are stocked in its native lakes, rivers and streams.

The result is that the fish has harmed its chances for survival, and the Endangered Species Act isn't clear about how to handle this type of situation.

'A head-scratcher'

In deciding a suit filed by five environmental groups and a sport fisherman, a U.S. district judge in Washington last week told the government to rethink its 2000 decision not to protect the cutthroat under the Endangered Species Act.

Judge Emmet Sullivan said the agency should have better weighed the risks created when the native cutthroat breed with nonnative fish.

In a ruling that touches on genetic purity and species protections, Sullivan was particularly troubled by the government's decision to count the hybrid fish when it tallied the westslope cutthroat population, and still conclude that interbreeding threatens the fish.

Within one year, he wants the government to finish a new review about whether to protect the fish.

Lynn Kaeding, Fish and Wildlife's supervisory fishery biologist in Bozeman, Mont., said he doesn't know what the agency will do next, though it is considering an appeal.

"This is a head-scratcher," he said. "I have a hard time personally and professionally coming to the conclusion that the (hybrid) fish isn't important."

Kaeding thinks the ruling may mean the agency has to improve the criteria used when it decides whether a fish is close enough to a cutthroat to be counted as one.

That may require more biochemical testing, which means the fish have to be killed to study them. This is less than desirable and costly, Kaeding said.

Sensitive species

Westslope cutts live in parts of Montana, Idaho, northwest Wyoming, eastern Washington and the John Day River Basin in Oregon.

In 1997, American Wildlands and other environmental groups petitioned the Fish and Wildlife Service to have the fish protected as threatened under the Endangered Species Act.

Cutthroats are highly dependent on clean, cold streams. But logging, mining and other development in wild lands are making it more difficult for the trout to find suitable habitat.

Other trout that have been introduced in the westslope cutthroat's waters -- including rainbow and brook trout -- are also out-competing the cutthroat.

Cutthroat trout can be distinguished from rainbows most easily by the bright red-orange slashes of color under their lower jaws.

Unlike rainbows, they have teeth in their throats between the gill arches and typically have longer heads and jaws.

Colorations vary, but the dark spots on the cutthroats' sides are generally larger than those on rainbows. Anglers know them as the most aggressive biters of the trout species, making them easier to hook than rainbows, brook trout or German browns.

Place in history

Rob Ament, executive director of American Wildlands, and other environmentalists see the case as the first major suit to question interbreeding and hybrid fish.

If the cutthroat disappear, Ament believes the country is in danger of losing a piece of its heritage. Lewis and Clark described the cutthroat in 1805 during their expedition west, and the fish's scientific name is Oncorhynchus clarki lewisi.