DENVER – Upside-down rivers of warming ocean water are a threat to the stability of floating ice shelves in Antarctica, according to a new report from the University of Colorado's National Snow and Ice Data Center.

Ice shelves are thick, floating plates of ice that have drifted away from the continent and spread out onto the ocean.

Karen Alley, a doctoral student who led the study, says knowing how shelves work will become more important as the planet gets warmer.

"They run into islands and peninsulas and pieces of the bedrock that help hold back the ice on the continent,” she explains. “And so if you lose an ice shelf, suddenly the ice behind it can flow much more quickly into the ocean. So they're really important for regulating sea-level rise."

The University of Colorado research found upside-down rivers, or basal channels, all around the Antarctic continent.

Alley says in many cases, the channels were making the ice shelves more vulnerable to collapse. She notes that while shelves take thousands of years to grow, they can disintegrate in a matter of weeks.

Both NASA and the National Oceanic and Atmospheric Administration have confirmed that February 2016 was the planet's warmest February since record keeping began in 1880.

Alley notes that ice shelves are especially vulnerable because climate change hits them from the air above and water below. She says although more research is needed to find all factors that can destabilize shelves, the basal channels are a key discovery.

"This is one potential factor,” she states. “If we're going to predict how sea level rise will work in the future, how fast things will change, we have to understand ice shelves."

When a channel is carved into the underside of an ice shelf, the top sags, leaving a visible wrinkle on the smooth surface. Alley's team used satellite photos to map wrinkles across the continent, and radar imaging to locate the rivers flowing beneath the ice.







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A working group convened by the California Department of Fish and Wildlife meets today to consider a partial closure of the commercial Dungeness crab fishing season, amid concerns too many whales and sea turtles are getting tangled up in the crab gear.

The ropes, which run from crab traps on the seafloor up to a buoy on the surface can become twisted around an animal's body. Last year, the gear entangled at least five humpback whales and killed a critically endangered Pacific leatherback sea turtle.

Andrea Treece, senior attorney for Earthjustice, a nonprofit public-interest environmental law organization, detailed the concerns.

"We leave too much gear on the water too late in the season, we wait until the risk is elevated," Treece pointed out. "Too often, it's too late to protect those whales. And so we need to really learn our lesson from the past."

The danger is greatest in the spring, summer and fall, when humpback whales migrate to California from Mexico and South America. The Department of Fish and Wildlife's risk assessment team is recommending the commercial fishery close April 5 south of the Sonoma/Mendocino County line, and would restrict the depth at which the crab traps can be set in northern California waters.

Treece thinks the department should announce a statewide closure as soon as possible, as it will take weeks to retrieve the gear and whales can quickly move north into areas with a lot of gear still in the water. She added a new type of ropeless gear is being tested, which could make a big difference once it is approved for use.

"We could be looking at a future where this fishery has to operate between January and March," Treece noted. "With a thoughtful transition to ropeless gear, we could be looking at a future where the fishery is operating for its full season."

A new public service announcement from the nonprofit Oceana includes video of a humpback whale filmed in 2022, entangled in ropes. The whale swam more than 1,000 miles, dragging the discarded crab gear for a year before it was discovered.


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A new bill aims to reduce the number of sea lions, sharks, rays, skates and giant sea bass dying off the coast of Southern California in huge set gillnets the size of 20 football fields, weighted to the sea floor.

Right now, set gillnets are banned in most state waters and Assembly Bill 2220 would extend the ban to a 3-mile radius around the Channel Islands.

Caitlynn Birch, Pacific marine scientist for Oceana, said the bill also stops crews profiting from certain species accidentally caught in the nets.

"It will remove the exemption that allows set gill net fisheries to incidentally catch and sell great white sharks and giant sea bass, which are both protected species and not allowed to take commercially or recreationally for any other fisheries in California," Birch pointed out.

Opponents cited concerns about the effect on fishing crews' bottom line. About 30 fishermen still have active set gillnet permits in Southern California. The state has stopped issuing new permits and the bill would make existing permits nontransferable.

The bill would also give the California Department of Fish and Wildlife the authority to require independent monitors on fishing boats but would not make them mandatory. Right now it is up to fishing crews to self-report when they accidentally catch a protected species.

"Having the authority to place third-party observers on vessels would allow for the collection of unbiased data on specifically bycatch, which is being thrown overboard at sea and isn't otherwise able to be tracked," Birch explained.

Supporters contended more selective hook and line fishing methods have significantly less bycatch and typically yield higher prices for fish considered better quality seafood.

Good news for fishing crews and marine conservationists: Large fishing grounds are reopening, while other areas receive new protections.

Some 4,500 miles of ocean fishing grounds off Southern California are now open to recreational and commercial fishing for bottom-dwelling species, and 428 miles of coral and sponge habitat are closed.

Geoff Shester, California campaign director and senior scientist for the nonprofit Oceana, said his organization has spent years mapping the seafloor, discovering colorful coral beds he said are "right out of a Dr. Seuss book."

"These areas have some of the richest gardens of underwater deep-sea corals and sponges anywhere," Shester reported. "We wanted to make sure that these areas had special protection, so that no bottom-contact fishing can damage some of these really sensitive 'redwoods of the deep sea.'"

The fishing grounds in question had been closed for 20 years to protect a species known as the cowcod rockfish, which has recovered from previous overfishing. The entire area is still closed to bottom trawling but the hook-and-line method and groundfish bottom longlines and traps are now permitted.

The areas now reopening include prime fishing grounds off San Diego. The eight areas to be newly protected are near the Channel Islands and far offshore seamounts, 100 miles from the coast.

Shester pointed out Oceana collaborated with commercial fishing groups and the State Department of Fish and Wildlife to determine the areas most worthy of extra protection.

"They went into place without opposition, because it was done in a thoughtful way where there were compromises made and we brought data and science forward," Shester recounted. "It's an example of how fishing and conservation groups can work together to support the shared goals of healthy fishing, as well as protecting seafloor habitats."

Deep-sea corals and sponges are a crucial part of the marine ecosystem, sheltering many species from predators and serving as feeding areas and nurseries. They are among the most long-lived creatures in the ocean.