Fifteen river otters from southern Alaska are being released in Daggett County to help rebuild Utah's population of the sleek mammals.

One pair was released Wednesday in the Green River about five miles below Flaming Gorge Dam. Another 13 are expected later this fall. All will be fitted with radio transmitters to allow biologists to track their movements and monitor habitat preferences.Ken McDonald, fur-bearer biologist for the Utah Division of Wildlife Resources, said nine river otters were released in the Green River last year near Little Hole. All appear to have survived and are now popular attractions for people fishing the river.

Little Hole was selected for the first releases because of repeated otter sightings in that section of the river during the last decade, McDonald said. Biologists hope to bolster the native population with their Alaskan cousins.

A five-year plan calls for river otters to be released at several locations between Flaming Gorge and the Green River's confluence with the Colorado River in Canyonlands National Park. The next release spot is Browns Park.

McDonald said it costs about $350 to capture, transport and release each otter. Money for the reintroduction program has been supplied by the non-game tax checkoff on Utah income tax forms, the U.S. Forest Service, a group of Utah trappers, and private contributions.

Students at Kearns High School raised $900 for the otter program.

McDonald said river otters have three basic requirements: clean water, a healthy riverside community of plants, and a good prey base. All of these conditions are met in the Green River below Flaming Gorge.

Russ Findlay, a Brigham Young University graduate student who will be monitoring the animals, said river otters may improve the nationally famous trout fishery in the Green River because they prefer to eat slow-moving types of fish, such as suckers and chub, which compete with trout.

McDonald said the river otters released this week - a male and a female - each weighed about 18.5 pounds, normal for a male but large for a female.

He said river otters prefer deep pools in the river where they can catch fish. They also move up tributary streams to chase fish in beaver ponds.

Otters are active year-round but use burrows for resting. They don't dig their own burrows, preferring instead to use such things as old beaver lodges, rock piles and fallen logs.