WASHINGTON — President Bush called for a halt to destructive fishing on the high seas Tuesday and said the United States will work to eliminate or better regulate practices such as bottom trawling that devastate fish populations and the ocean floor.

Bush directed the State and Commerce departments to promote "sustainable" fisheries and to oppose any fishing practices that destroy the long-term natural productivity of fish stocks or habitats such as seamounts, corals and sponge fields for short-term gain.

He said the United States would work with other nations and international groups to change fishing practices and create international-fishery regulatory groups if needed.

The memo was issued a day before United Nations negotiations open in New York on an effort to ban bottom fishing anywhere it's unregulated. While Brazil, Chile, Germany, the Netherlands, South Africa and, now, the United States have expressed support for regulating bottom trawling on the high seas, Spain, Russia and Iceland are among those that oppose it.

The high seas — which extend beyond nations' 200-mile offshore exclusive economic zones — cover nearly two-thirds of the planet, yet only about a fourth of it is subject to international treaties.

The United States allows but regulates bottom fishing in its waters. The practice involves boats dragging huge nets along the sea floor scooping up fish while bulldozing nearly everything else in their path.

"It's like clear-cutting the forest to catch a squirrel," said Joshua Reichert, head of the private Pew Charitable Trusts' environment program, which has been leading an international coalition against the practice.

"The White House ... has once again come out strongly in support of ocean conservation, proving that there is bipartisan support for ending the destruction of the world's oceans," Reichert said.

Bush created a national monument in June to protect the Northwestern Hawaiian Islands and surrounding waters, an archipelago 1,400 miles long and 100 miles wide in the Pacific Ocean.

His position represents a last-minute shift going into an election, in part because of mounting pressure from conservation groups and key GOP senators such as Ted Stevens of Alaska.

"The United Nations must put an end to unregulated fishing practices on the high seas ... " Stevens said Tuesday.