WELLINGTON, New Zealand (AP) — Antarctica's Ross Sea is often described as the most isolated and pristine ocean on Earth, a place where seals and penguins still rule the waves and humans are about as far away as they could be. But even there it has proven difficult, and maybe impossible, for nations to agree on how strongly to protect the environment.

The United States and New Zealand have spent two years trying to agree on an Alaska-sized marine sanctuary where fishing would be banned and scientists could study climate change. U.S. Secretary of State Hillary Rodham Clinton took a strong interest in the outcome, regularly prodding diplomats, and New Zealand recently sent a delegation to Washington to reach a tentative deal.

That compromise, over a region that accounts for less than 2 percent of New Zealand's fishing industry, flopped this month when senior New Zealand politicians rejected it behind closed doors.

The U.S. and New Zealand have now sent competing plans to the 25 countries that meet annually each October to decide the fate of Antarctica's waters. Their inability to agree greatly increases the chances that nothing will get done.

Evan Bloom, director of the U.S. State Department's Office of Ocean and Polar Affairs, said the U.S. put a great deal of effort into its reserve proposal because it believes the Ross Sea is the best place on Earth for scientists to carry out studies away from the influence of mankind.

"If you can't do it in Antarctica, where can you do it?" said Bloom.

Both countries advocated for marine sanctuaries. The differences between the two plans seem small on a map, but they center on the areas of the sea where marine life is most abundant.

The U.S. does not have fishing interests in the Ross Sea, though fish caught there often end up in high-end American restaurants, marketed as Chilean sea bass.

The species is actually an ugly creature called the Antarctic toothfish. Fishermen from New Zealand, South Korea, Russia and other nations have been catching them in the Ross Sea since the 1990s. They use lines that can stretch more than a mile to catch about 100,000 of them a year.

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The U.S. aimed to reach an agreement with a nation that fishes the Ross Sea in hopes it would lead to a broader deal to protect marine habitats there.

New Zealand wanted to minimize disruption to its fisheries, but also wanted to burnish its conservation credentials. The country not only prides itself as an environmental leader, but it also makes money by marketing its clean, green image to trading partners and tourists. And it has criticized other nations' environmental records at sea, particularly nations that allow whaling.

Clinton urged diplomats to craft a deal. When she visited the Cook Islands last month, she described the Ross Sea as "one of the last great marine wilderness areas on the planet" and said the U.S. was working with other countries, "in particular New Zealand," to establish protected areas. Murray McCully, New Zealand's foreign affairs minister, echoed her comments.

Late last month, senior New Zealand diplomat Gerard van Bohemen led a team to Washington that spent four days grinding out the details of a compromise. After he brought the proposal back to New Zealand's ruling National Party, its senior Cabinet of lawmakers met in a closed session and rejected it.

Exactly why, they're not saying. Van Bohemen and Cabinet minister Steven Joyce declined to give interviews.

McCully also declined to discuss what happened, although he said in an email that New Zealand will keep working closely with the Americans.

The Ross Sea fishery is small on a global scale, worth about $60 million per year. The New Zealand Seafood Industry Council says New Zealand's Ross Sea catch accounts for just $16 million of a national industry worth over $1 billion.

But council spokesman Don Carson said New Zealand relies on dozens of species being fished in dozens of places. "None of them are huge, but they are very diverse, and we are keen not to lose any of them," he said.

Carson said the Ross Sea is being fished conservatively and sustainably, so further restrictions are unnecessary.

"We fish in a very limited area for a very limited season," he said. "We don't want to be buffeted by the winds of popular sentiment when that sentiment is based on a misapprehension of what's going on."

Antarctic fishing is regulated by the Commission for the Conservation of Antarctic Marine Living Resources, the 25-nation group scheduled to meet next month. Its executive secretary, Andrew Wright, said fishing in the Ross Sea is carefully regulated with quota limits set each year, and that available science points to the fishery being sustainable.

Peter Young, a New Zealander who recently directed an environmental advocacy documentary on the sea titled "The Last Ocean," said an international agreement that protects Antarctic land from exploitation should be extended to its seas.

"Almost every other ocean on earth has been impacted and affected by humanity," he said. "We're down to the last few places, and we've got to protect it and have something to hand on to future generations."

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