Sustainability can mean a lot when it comes to fish. This means that there was and is a lot of pollock in the place where your fish was caught. It means that the boat that dragged its net through the ocean didn’t harm the ecosystem. And it means that the boat only caught a few “by-catches”.
It is difficult to figure out how to limit bycatch. It’s something the Marine Stewardship Council (MSC), which certifies sustainable fishing, has been working on for 20 years.
Bycatch is any animal you don’t intend to catch. Alaska’s pollock fishery used to absorb a lot of salmon bycatch. Some Pacific salmon species are endangered and many indigenous people rely on them for food. Accidentally catching this salmon was a serious problem.
So Alaska fishermen use salmon lockouts. These are escape hatches that allow salmon to escape from pollock nets. Now, “fishermen are catching exactly what they are trying to catch,” said Dan Averill, fisheries manager at MSC. Salmon bycatch is less than 1 percent of the total catch.
But this is only one small piece of the bycatch puzzle.
The state of Oregon has a pink shrimp fishery. About 41,000 pounds of these three-inch crustaceans are caught there every year. But the fine-mesh nets used to catch shrimp also catch eulachon. This is a silvery smelt that is important food for many other fish and seabirds.
“Anything no smaller than the shrimp won’t come out of the net,” says Scott Groth. He is a shellfish project leader for the Oregon Department of Fish and Wildlife.
Eulachon was listed as endangered more than a decade ago and was given protection under the Endangered Species Act. That meant researchers had to ramp up their efforts to keep eulachon out of shrimp nets, which are dragged into the ocean about 16 inches above the bottom.
“We thought, what if we could show these fish, ‘Hey, there’s freedom?’ Groth says about the space under the nets. They came up with the idea of using LED lighting to direct fish to that area. The idea worked, especially when researchers used green light. Fishermen started placing as many as 40 of them on the bottom of their nets. Now Groth has found that the ideal number is 5. Researchers aren’t sure why, but the lights could “dramatically” reduce the amount of eulachon bycatch, he says.
Tori lines and banana pingers
Bycatch doesn’t just refer to the fish we eat. It can also mean marine mammals such as dolphins and sea birds such as albatrosses. These animals can become entangled in nets when they try to eat the catch from fishing boats. Dolphins and birds can drown as a result – one of the biggest threats to them and to whales, sharks and sea turtles around the world. This result is “unwanted by everyone,” said Rob Enever, chief of science at a company called Fishtek Marine.
Fishstek invented the banana pinger. This yellow device also attaches to fishing nets; its banana-like curvature keeps it from snagging on machines aboard fishing boats. “When the nets are submerged in water, the banana pingers automatically turn on and make a high-pitched sound that dolphins and porpoises can hear,” Enever says. They swim away to avoid that noise.
The pingers have managed to keep endangered river dolphins out of Indonesia’s fishing nets. They also help the fishing companies: fewer dolphins eating caught fish means more for the fishermen to sell.
No noise is needed to deter seabirds with a device called a tori line. This is a filament that hangs from the back of a fishing boat. It is strung with streamers that flutter in the wind and scare away birds. For example, they have reduced the number of petrels caught in fishing lines in the hake fishery in South Africa. In some cases, tori lines have reduced seabird bycatch by as much as 98 percent.
These and other bycatch solutions scientists have come up with are “a real success story,” Averill says. They all help make our oceans more sustainable.