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09/09/2011 11:59 am ET | Updated Nov 09, 2011

Deep-Sea Fishing: Marine Scientists Call For Sustainable Alternatives

There are plenty of fish in the sea ... or are there?

An international group of marine scientists are calling for an end to most deep-sea fishing and supportive government subsidies after finding that most deep-sea fisheries are unsustainable.

"The deep sea is by far the largest but least productive part of the ocean," according to a recent study published in the journal Marine Policy.

"We're doing some of the world's most destructive fishing in the world's worst place to fish," Elliott Norse, president of the Marine Conservation Institute in Bellevue, Wash., and the lead author of the study, told The Huffington Post. He added, "If it continues, fish that were once abundant become rare or extinct. Damage is caused that can take decades, centuries or longer to recover."

Unfortunately, Norse said, "It is economically rational for trawlers to seek out a concentration of deep-sea fish -- like an oasis in the desert -- and fish them down to a point where it is no longer economically viable and move on."

Trawling, a method of deep-sea fishing that involves scraping huge metal plates across the ocean floor, kills fish, sharks and coral that people do not eat. The unwanted dead are just thrown back into the sea, the study says.

"We're talking about the frigid black depths of the ocean where fishes are very slow to mature and can't recover quickly from fishing pressure. They didn't evolve in situations where giant trawlers scoop them up," Norse said.

Some species of deep-sea fish can live for more than a century and some corals can live for 4,000 years, according to a statement released by the Marine Conservation Institute. The poster child for slow-maturing deep-sea fish being wiped out by bottom trawling is the orange roughy. The fish takes 30 years to reach sexual maturity and can live to more than 125 years.

Norse said that to stop fishing for orange roughy would not reduce the world's food supply. "Orange roughy are only eaten by affluent people in places like Japan, Korea, the U.S. and Europe. We're not talking about feeding the poor here, we're talking about feeding the rich."

Another author of the study, New Zealand-based fisheries biologist Malcolm Clark, noted that fishing for orange roughy in New Zealand grew rapidly during the 1980s and 1990s. "Most of the fisheries were overexploited, and catch levels have either been dramatically reduced or the fisheries closed all together," he said in the institute's statement.

Ray Hilborn, professor of aquatic and fishery sciences at the University of Washington, said the study was correct that deep-sea fishing is not managed, but added that the study did not say what should be done.

"They're basically saying we shouldn't do it without saying what we should do," Hilborn told HuffPost. "Long-lived species can be sustainably managed. They can be managed if they are harvested at a low rate and have a science program set up that regulates their abundance."

Coastal-water fisheries are much more productive, Norse said, but have also collapsed because of overfishing. There is no "magic way" to help overfished areas to recover, he said, and the only thing to be done is to stop killing the fish and "control our appetites."

But trawlers continue to fish the high seas, said Norse, "because the governments subsidize them heavily." According to study author Rashid Sumaila, a fisheries economist at the University of British Columbia, high-seas trawlers receive $162 million in government handouts each year.

"They don't have an incentive to fish sustainably," Norse said. That's why he urges the United Nations and individual countries to stop deep-sea fishing "unless you can prove that you're fishing sustainably."

The overfishing of coastal fisheries has slowly pushed commercial fishing fleets into waters that are more than a mile deep, according to Selina Heppel, a marine fisheries ecologist at Oregon State University and an author of the study. She said, “On the high seas, it is impossible to control or even monitor the amount of fishing that is occurring. The effects on local populations can be devastating.”

Hilborn told the Washington Post, “From a conservation perspective, maybe we shouldn’t fish at all, and the ocean should be left pristine." But then he wondered, "Where is the food going to come from?”

The call to close most deep-sea fisheries comes as the United Nations considers whether to continue to allow fishing in the high seas.