Long after commercial fishers have pulled into dock, their lost and abandoned gear continues fishing – threatening marine wildlife and habitats around the world.
Some call it “ghost fishing.”
A recent NOAA study found that abandoned and lost fishing gear has “persistent and pervasive” impacts on U.S. waters. It also found that these impacts are largely reversible.
A good case study is the recovery of derelict crab pots on the Washington coast, a comprehensive effort involving Tribal and non-tribal commercial fishers, scientists, agencies and organizations like The Nature Conservancy.
The bottom line: collaborating on crab pot removal benefits both fish and fishers.
The Ghosts of Crab Pots
The Dungeness crab is one of the most important fisheries in Washington, with an average of 14 million pounds of the crustaceans harvested annually.
The crabs are captured in wire traps, called crab pots. About 90,000 to 100,000 of these pots are set in Washington waters annually.
Crab pots are not inexpensive; each one costs about $225. Still, heavy winds and other harsh conditions mean that about 10 percent of the pots are lost each year.
That’s a lot of pots in the water. Still fishing.
There are the direct impacts: crabs and other wildlife continue to be caught. As they die, the traps become what NOAA calls “self-baiting” – continually attracting new predators until the trap is buried.
The trap is attached to a buoy by polyethylene line that poses threats to both whales and boats.
Derelict crab pots are truly ghosts that continue to haunt the seas.
The challenge is obvious: You’re looking for ghosts. In the ocean.
Prevention & Recovery
The old cliché about an ounce of prevention is true here. Crab pots will be lost. But their impacts can be prevented in part by trap design.
Traps can be assembled using a biodegradable binding that breaks down over time. This shortens the crab pot’s “ghost fishing” capabilities.
Despite this, sediment can sometimes build up and keep the pots open and operating even if the binding material degrades.
As such, recovering the pots is the only real way to ensure the crab pots aren’t having negative impacts. The State of Washington allows fishers to go out and retrieve pots – even those that don’t belong to them – after the fishing season ends.
“That policy has been very effective in cleaning up pots,” says Eric Delvin, community conservation coordinator for The Nature Conservancy in Washington.
But the policy does not apply to Tribal waters. The Quinault Indian Nation manages a significant Dungeness crab fishery, with about 40,000 pots in the water annually.
The Conservancy and Quinault Nation partnered to remove derelict pots, seeking every possible way to get them out of the water.
The Tribal fishing waters cover 155 square miles. And crab pot removal faces some notable logistical challenges.
“We have a very short window of opportunity to do the removal,” says Delvin. “The currents are so strong on the coast. It can pull buoys under the water. It takes four hours to get a boat to the removal project. So we have to be as efficient as possible.”
How to accomplish that, especially when crab pots are spread over a large area? Here’s a look at what has worked in Quinault-Conservancy partnership.
Take to the Air. Crab pot buoys can be seen from a boat. But it’s even more effective to find and map them by airplane.
“We fly the area and estimate how many crab pots are out there, and estimate where the greatest accumulations are,” says Delvin. “Due to sea currents, the pots tend to accumulate in certain areas. The air enables us to focus our time on places we’ll have the most impact.”
Divers Manual. The most low-tech approach is to remove the traps manually, by sending divers down and retrieving them.
It’s effective, but it’s also expensive. Conditions also have to be relatively calm to ensure safety – not a given in rough Pacific waters. Even in the best of conditions, visibility is low.
Sand Blasters. One of the biggest challenges is that the pots can be buried by sand, making manual recovery seemingly impossible.
Enter a hydraulic pump. It liquefies sand around the pot, allowing the team to easily remove pots buried up to four feet.
Cutting the Line. Some pots are buried below four feet, so even the hydraulic pump won’t work. In this case, the trap will remain. But there is still the risk from the polyethylene line. Even a small amount of line can harm wildlife.
In the past, a diver would have had to go all the way to the sea bottom to cut the line. But an innovative line cutter – developed by Crayton Fenn of Fenn Enterprises and Kyle Antonelis of Nature Resources Consultants – travels down the line to the bottom.
Researchers then snip it off at the ocean floor so that no line remains suspended in the water column.
“Our goal is to recover every pot,” says Delvin. “We know we can get pots buried up to four feet. After that, we get the line out as quickly as possible. Then it’s on to the next pot.”
Initial results are promising with more than 150 traps removed in just four days in 2014; Delvin says an even more concerted effort will begin in 2015. And the Conservancy is looking with other partners and opportunities to remove gill nets and other derelict gear.
“Pacific fisheries are well managed and in relatively good shape,” says Delvin. “Our goal here is to work with fishers to make their industry even more sustainable.”