Lela Nargi
THE WASHINGTON POST – If you’ve ever eaten a fish filet sandwich from a fast-food restaurant, you may have eaten pollock. Pollock is a species of groundfish that lives near the bottom of the ocean. The pollock nestled into that squishy sandwich bun came from the waters around Alaska with the promise that it was caught sustainably.
Sustainability can mean lots of things when it comes to fish. It means that there were and still are plenty of pollock in the place where your fish was caught. It means that the boat towing its net through the ocean didn’t hurt the ecosystem. And it means that the boat took in only a few “bycatch”.
Figuring out how to limit bycatch is tricky. It’s something the Marine Stewardship Council (MSC), which certifies sustainable fisheries, has been working to solve for 20 years.
WHAT IS BYCATCH?
Bycatch is any animal that you don’t intend to catch. Alaska’s pollock fishery used to take in a lot of salmon bycatch. Some Pacific Ocean salmon species are endangered, and many Indigenous people rely on them for food. Catching these salmon by accident was a serious problem.
So Alaska fishers use salmon excluders. These are escape hatches that let salmon out of pollock nets. Now “fishers are catching just what they’re trying to catch”, said Fishery Manager at MSC Dan Averill Salmon bycatch is down to less than one per cent of the total catch.
But this is only a tiny piece of the bycatch puzzle.
LED LIGHTS AND EULACHON
The state of Oregon has a pink-shrimp fishery. About 41,000 pounds of these three-inch crustaceans are caught there each year.
But the fine-mesh nets that catch shrimp also catch eulachon. This is a silver-coloured smelt that is important food for lots of other fish and seabirds.
“Anything that’s not smaller than the shrimp is not getting out” of the net, said Scott Groth. He’s a shellfish project leader for the Oregon Department of Fish and Wildlife.
Eulachon were listed as threatened and given protections under the Endangered Species Act more than a decade ago.
That meant researchers needed to step up their efforts to keep eulachon out of shrimp nets, which are dragged in the ocean about 16 inches above its floor.
“We thought, what if we could show these fish, ‘Hey, there’s freedom down there?'” said Groth about the space beneath the nets.
They came up with the idea to use LED lights to guide fish toward that area. The idea worked, especially when researchers used green lights.
Fishers started by placing as many as 40 of them at the bottom of their nets. Now Groth has found that five is the ideal number.
Researchers aren’t sure why, but the lights can reduce the amount of eulachon bycatch “dramatically”, he said.
TORI LINES AND BANANA PINGERS
Bycatch doesn’t only refer to the fish we eat. It can also mean marine mammals such as dolphins and seabirds such as albatrosses. These animals can get caught in nets when they try to eat fishing boats’ catch.
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 head of science at Fishtek Marine Rob Enever.
Fishtek invented the banana pinger. This yellow device is also attached to fishing nets; its banana-like curve keeps it from getting snagged on machines onboard fishing boats. “When the nets are submersed in water, the banana pingers automatically turn on and make a high-pitched sound that dolphins and porpoises are able to hear,” Enever said. They swim away to avoid that sound.
The pingers have been successful in keeping threatened river dolphins out of fishers’ nets in Indonesia. They also help the fishers’ businesses: Fewer dolphins eating caught fish means more for the fishers to sell.
No sound is needed to scare off seabirds with a device called a tori line. This is a filament that hangs off the back of a fishing boat. It is strung with streamers that flap in the wind, shooing birds away. They have reduced the number of petrels caught in fishing lines in the hake fishery in South Africa, for example. In some cases, tori lines have reduced the bycatch of seabirds by as much as 98 per cent.
This and other bycatch solutions that scientists have devised are “a real success story”, Averill said. They all help our oceans become more sustainable.
