A team of leading marine scientists from around the world is recommending an end to most commercial fishing in the deep sea. Instead, they recommend fishing in more productive waters nearer to consumers.

In a comprehensive analysis published online this week in the journal Marine Policy, marine ecologists, fisheries biologists, economists, mathematicians and international policy experts show that, with rare exceptions, deep-sea fisheries are unsustainable. The “Sustainability of deep-sea fisheries” study, funded mainly by the Lenfest Ocean Program, comes just before the UN decides whether to continue allowing deep-sea fishing in international waters, which the UN calls “high seas.”

According to the Marine Conservation Institute, food is scarce in the Deep Sea and life processes happen at a slower pace than near the sea surface. Some deep-sea fishes live more than a century; some deep-sea corals can live more than 4,000 years. When bottom trawlers rip life from the depths, animals adapted to life in deep-sea time can’t repopulate on human time scales. Powerful fishing technologies are overwhelming them.

The deep sea provides less than 1% of the world’s seafood. But fishing there, especially bottom trawling, causes profound, lasting damage to fishes and life on the seafloor, such as deep-sea corals, experts say.

Since the 1970s, when coastal fisheries were overexploited, commercial fishing fleets have moved further offshore and into deeper waters. Some now fish more than a mile deep.

“Because these fish grow slowly and live a long time, they can only sustain a very low rate of fishing,” says author Dr. Selina Heppell, a marine fisheries ecologist at Oregon State University. “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.”

The authors document the collapse of many deep-sea fishes around the world, including sharks and orange roughy. Other commercially caught deep-sea fishes include grenadiers (rattails) and blue ling.

“Fifty years ago no one ate orange roughy,” said author Dr. Daniel Pauly, a fisheries biologist with the University of British Columbia (UBC). “In fact, it used to be called slimehead, indicating no one ever thought we would eat it. But as we’ve overfished our coastal species, that changed and so did the name.”

Orange roughy take 30 years to reach sexual maturity and can live 125 years. Compared with most coastal fishes, they live in slow-motion. Unfortunately for them and the deep-sea corals they live among, they can no longer hide from industrial fishing.

There are very few exceptions to unsustainable deep-sea fisheries around the world. One is the Azores fishery for black scabbardfish. There the Portuguese government has banned bottom trawling, which overfished black scabbardfish elsewhere. Azores fish are caught sustainably with hook and line gear from small boats. In most deep sea-fisheries, however, trawlers fish outside of nations’ 200-mile Exclusive Economic Zones, outside of effective government control.

High seas trawlers receive some $162 million each year in government handouts, which amounts to 25% the value of the fleet’s catch, according to Dr. Rashid Sumaila, an author and fisheries economist at UBC.

The authors of this Marine Policy paper say that the best policy would be to end economically wasteful deep-sea fisheries, redirect subsidies to help displaced fishermen and rebuild fish populations in productive waters closer to ports and markets, places far more conducive to sustainable fisheries.

“Instead of overfishing the Earth’s biggest but most vulnerable ecosystem, nations should recover fish populations and fish in more productive coastal waters,” says Dr. Norse. “Deep-sea fishes are in deep trouble almost everywhere we look. Governments shouldn’t be wasting taxpayers’ money by keeping unsustainable fisheries afloat.”

Further Reading:
Marine Conservation Institute: Are Deep Sea Fisheries Sustainable