Pacific Ocean Lingcod Stocks May Benefit From New Gear

By on May 27, 2016
Pacific Ocean lingcod fish. (Credit: Flickr User Eva Funderburgh via Creative Commons 2.0)

Pacific Ocean lingcod used to be overfished, to the point where managers created protected areas for the fish and other depleted groundfish species, such as yelloweye and canary rockfish.

Some lingcod have since recovered well with commercial and recreational fishing restrictions and closures, called rockfish conservation areas. These safe zones have given them space to run from predators, as well as the nets of fishermen. But other rockfish species also designated as overfished haven’t yet recovered, even with vast fishing closures.

While fishing closures have helped to rebuild some species, others still flounder due to lower reproduction and growth rates. Robust species like lingcod also eat the juvenile fish of these slower-growing species, further defeating their chances of recovery.

Scientists at the University of Washington together with The Nature Conservancy and West Coast fishermen are hoping to find a win-win solution to this imbalance. Specifically, scientists are looking at whether fishing for lingcod in closed areas using an innovative approach could still allow sensitive species to continue recovering.

The idea is to better manage the conservation areas that already exist and hopefully benefit both the fish and fishing communities. The crux of it is to allow fishing for Pacific Ocean lingcod in rockfish conservation areas that could take some of the pressure off juveniles so they can grow bigger and stronger to rival other lingcod.

An example of the new lingcod fishing gear. The two “wings” guide fish into tunnels that lead into the main chamber. A grid resembling a tic-tac-toe board keeps large flat fish (like halibut) out, while letting Pacific Ocean lingcod in. If other fish do get inside the chamber, the trap is designed to let smaller fish swim out through the sides and top and flat fish shimmy out the bottom. (Credit: The Nature Conservancy)

An example of the new lingcod fishing gear. The two “wings” guide fish into tunnels that lead into the main chamber. A grid resembling a tic-tac-toe board keeps large flat fish (like halibut) out, while letting Pacific Ocean lingcod in. If other fish do get inside the chamber, the trap is designed to let smaller fish swim out through the sides and top and flat fish shimmy out the bottom. (Credit: The Nature Conservancy)

The UW scientists examined this predator-prey relationship between lingcod and rockfish to see if allowing lingcod fishing in rockfish conservation areas could take some of the pressure off of rockfish and let small juveniles grow bigger and stronger to rival lingcod. Their models showed that modestly fishing for lingcod in these areas using different, more selective gear could avoid harming rockfish. It would also benefit fishermen and could bring more tasty fish to the market.

The idea to use a different method to catch lingcod without bothering other fish came from fishermen in Ilwaco, Washington, who approached The Nature Conservancy with the proposal. Together with input from fishermen in the area, ecologists from organization have developed a lingcod trap that looks much like a crab pot, but with some added measures to allow lingcod in and push out other species that swim in.

Pending permits, ecologists hope to test the new gear in lingcod-heavy waters along Washington and Oregon next year. They currently can’t test the new gear in conservation areas that are closed to use of pot gear, where concentrations of lingcod are higher.

The UW researchers caution this is a pilot study to explore a different approach to ecosystem management, and more information must be collected before the conservation areas could support fishing. It’s critical to understand lingcod diets, including how much rockfish they eat and what size is palatable.

Since 2002, large swaths of the Pacific Ocean from Baja to Vancouver Island have been closed to trawl fishing, a method that pulls nets along the seafloor and scoops up a lot of unintended marine plants and fish species. Trawling, while effective in catching an abundance of fish quickly, has had negative impacts on some groundfish populations, including rockfish species and Pacific Ocean lingcod.

Full results of the effort are published in the ICES Journal of Marine Science.

Top image: Pacific Ocean lingcod fish. (Credit: Flickr User Eva Funderburgh via Creative Commons 2.0)

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