The spill occurred off the sprawling Alaska Maritime National Wildlife Refuge in an area important for commercial fishing, seabirds and wildlife. Refuge Manager Greg Siekaniec said federal biologists are trying to estimate overall environment damages from the spill.

That estimate will be translated into a dollar figure to be used as a basis for a possible civil fine or settlement, he said.

There were more than 1,600 dead oiled birds collected in the wake of the spill, as well as a handful of oiled sea otters, he said. "We know if you pick up 1,600 birds, there's going to be more. The question is how much more," Siekaniec said.

Leslie Pearson, director of the department's prevention and emergency response program, said beach cleanup will resume next summer because not all the necessary work was completed in the past summer. The state is also working on a plan to have the owner remove the wrecked vessel, she said.

On-site work cannot be done in the winter, when daylight is scarce and fierce storms are common, she said. Over the winter, officials expect storms to move the vessel's severed halves and continue to leak some of the oil that has been clinging to the inside, she said.

"We know that there's residual oil left in the stern, and what we're going to see is that residual oil get released," she said.

Environmentalists this week said too little has been done to improve safety of the so-called "Great Circle" route between North America and Asia, a route that uses a narrow passage through the Aleutian Islands. About 3,000 large ships use the route each year, they said, and the number is expected to grow, they said.

Improvements promised after last year's wreck, such as an area-wide risk assessment, ship-tracking systems and dedicated, high-power rescue tugs, have yet to materialize, they said.

"If there was a vessel like the Selendang drifting on the ocean right now, there's a high likelihood that we would see the same thing happen again," Rick Steiner, a marine science professor at the University of Alaska and founder of a new group, the Shipping Safety Partnership, said at a news conference Wednesday.

The group recommends that the Selendang Ayu's owner settle state and federal natural resource claims for $200 million, and pay an additional $50 million for dedicated rescue tugs.

A spokesman for the Selendang Ayu's operator said the company and the shipping industry as a whole are working to improve cargo vessel safety.

"It's a constant, evolutionary effort," said Jim Lawrence, a spokesman for Singapore-based IMC Shipping.

One company change put into effect immediately was a policy mandating full survival suits for crew members instead of the small life vests worn by the drowned seamen, he noted.

The challenges of the Aleutian Islands are not unique, he added.