ANCHORAGE, Alaska — Large areas of the Bering Sea off Alaska's coast will soon be off-limits to bottom trawling, a practice involving fishing vessels that drag huge, weighted nets across the ocean floor.

Come Monday, nearly 180,000 square miles of the Bering Sea will be closed to bottom trawling, bringing the total in the Pacific Ocean to 830,000 square miles — an area more than five times the size of California.

Other newly restricted areas are off Washington, Oregon and California.

Conservation groups have long fought the practice of bottom trawling, calling it an outdated form of fishing that pulverizes delicate corals and sponges living on the sea floor. Scientists say it can take centuries for the slow-growing corals and sponges to recover, if they ever do, after bottom trawlers move through an area.

"It basically is taking a net and raking it on the bottom, and anything that sticks up from the bottom gets bulldozed over. It is similar to forest clear-cutting," Chris Krenz, Oceana's arctic project manager, said Friday.

In the northern Bering Sea, many animals rely on the crabs and clams that grow on the ocean floor for food, Krenz said.

The North Pacific Fishery Management Council, which advises the federal government on fisheries, unanimously voted in favor of the northern Bering Sea regulation in June.

In Alaska, bottom trawlers will be allowed to work about 150,000 square miles, mostly around the Aleutian and Pribilof islands.

The industry favored a temporary restriction to assess what areas needed protection, leaving nonsensitive sections open to bottom trawling.

Jim Ayers, vice president of Oceana, said the regulation essentially puts the northern Bering Sea off-limits to bottom trawlers. The fishing vessels had not been consistently venturing into the area but were starting to, he said.

Ayers said the effects of climate change in the Bering Sea, combined with bottom trawling, could have devastated essential fish habitat. According to Oceana, the Bering Sea has 26 species of marine mammals, including the North Pacific right whale, believed to be the most critically endangered whale in the world.

Blue, humpback, gray and bowhead whales also travel each year through the Bering Sea, which is a magnet for millions of seabirds who migrate each spring and summer to breed.

Bottom trawling "would really cause even more stress of the ecosystem," Krenz said.

The Groundfish Forum, a trade association of six trawl companies that fish in the Bering Sea and the Gulf of Alaska, said the regulation, while OK for now, could end up harming the industry.

"Should the concentrations of fish move to the north, it actually could be harmful to keep us from going where the fish are," said Lori Swanson, the forum's executive director.

It could mean fishing longer, keeping the nets on the bottom more, using more fuel and potentially increasing the number of bycatch, the non-targeted fish that are caught in the nets, Swanson said.