A federal judge in Alaska refused on Monday to allow state officials to launch an aerial wolf hunt on a federal wildlife refuge in the Aleutian Islands, an emergency effort to save a herd of caribou that is on the verge of collapse.

The ruling is the latest chapter in a legal battle between the state and the U.S. Fish and Wildlife Service that erupted after federal wildlife officials threatened to charge state game hunters with trespassing if they entered the refuge and began gunning down wolves.

While federal officials have engaged in a variety of predator control measures, no aerial wolf control program has ever been authorized on a federal wildlife refuge in Alaska.

U.S. District Judge H. Russel Holland in Anchorage declined the state’s request for a preliminary injunction, ruling that federal wildlife officials are allowed by law to complete their studies to determine the cause of the caribou decline and how to deal with the predator wolves before any emergency action.

The state Department of Fish and Game has warned that the caribou population on Unimak Island — the easternmost island in the Aleutians that is home to fewer than 100 mainly Alaska Native residents — is so precariously low that it could disappear if wolves are allowed to attack this summer’s newborn calves.

Residents have said the wolves are hungry, increasingly desperate and a potential threat to children. “The wolves don’t have enough caribou to eat, so they have to search for something else.… Where the wolves are camping out now are houses that have little 7- and 10-year-old children,” said Cindy Beamer, general manager of the Isanotski Corp., which represents Alaska Natives on the 1,571-square-mile island.

State officials have said they are obligated by law to maintain a healthy enough caribou herd to provide subsistence hunting of the animal for Unimak residents, who also depend on fishing.

While there were 1,200 caribou on the island in 2002, there were fewer than 300 during the official count in 2009. State officials in court Monday presented the results of a survey conducted Sunday that showed only an estimated 250 caribou surviving.

“They only actually counted 178, and they counted seven bulls,” said Bill McAllister, spokesman for the state Department of Law. Federal officials continue to believe there are at least 400 caribou remaining.

In any case, the extremely low number of bulls means it could be difficult or impossible for the herd to survive with further predation. The state went to court last week for an emergency order to hunt as many as seven of the island’s estimated 20 to 30 wolves by air.

Larry Bell, assistant regional director for the U.S. Fish and Wildlife Service in Alaska, said federal wildlife biologists agree that something must be done about the declining caribou population but need more time to determine the best course of action.

Over the years, the number of caribou on the island has ranged from several thousand to none, and federal officials have tried to allow predators and prey to maintain their own equilibrium.

“While we see there is urgency to this matter, we don’t believe it’s such a dire situation that we can’t take time to conduct a thorough analysis prior to acting,” Bell said.

He said federal officials expect to complete their analysis by December. They also expect to grant a permit on Wednesday to allow state officials to import additional caribou bulls onto the island, and they will launch a collaring program for caribou and wolves to allow both wildlife agencies to better understand what is happening.

kim.murphy@latimes.com