Want More Crab and Lobster? Go Fish for Lost Gear
Posted by Richard Conniff on January 29, 2016
Chesapeake Bay watermen took it hard in 2008, when their blue crab industry was officially declared a commercial failure. The blue crabs are to the Chesapeake what lobsters are to Maine, not just a major contributor to the economy but also the object of a venerable waterman culture, based on crab pots in warmer weather and dredging in winter.
Faced with decline of this iconic industry, Virginia opted to shut down the winter crab harvest in its waters. Scientific studies had shown that it dredged up a disproportionately large number of reproductive females, meaning fewer crabs to catch in future years. The crabbers were skeptical, at best, when the state offered to put them back to work during the winter retrieving derelict and abandoned crab pots. Pulling up empty crab pots in winter is nobody’s idea of a good time.
But the pots weren’t empty, “and that’s the headline,” said Kirk Havens, a biologist at William & Mary’s Virginia Institute of Marine Science (VIMS). In the middle of winter, the pots were loaded with bycatch, almost all of it dead—not just crabs, but striped bass, perch, catfish, even drowned muskrats and diving ducks.
That started to get the watermen, who had previously considered lost pots irrelevant to the fishery, thinking differently. It also led to a new study in the online journal Scientific Reports arguing that a program to recover as little as 10 percent of derelict crab and lobster pots worldwide could increase crustacean landings by almost 300,000 metric tons, worth $831 million annually, in addition to the benefit to nontarget wildlife.
The idea for the program arose when Havens and co-author Donna Bilkovic, a VIMS marine ecologist, were mapping the bay bottom with the help of side-scan sonar. “We kept seeing these weird rectangular shapes,” said Havens. They turned out, on closer inspection, to be abandoned crabs pots. A lot of them. Chesapeake Bay watermen put out up to 800,000 pots every year, and routinely lose 20 percent of them to storms, boat propellers, and other causes. Because the pots are metal, they can last and continue “ghost fishing” for years afterward, with the bodies of their victims serving as a form of continual “self-baiting” for other victims.
Federal disaster-relief funding for the fishery meant a chance to see if stopping or at least reducing this bycatch could make a difference, said Havens. Beginning in 2008, the recovery program put 70 watermen to work, searching along a systematic grid for lost pots. Havens and his academics had toyed with some sort of grappling device to recover the pots. “But the watermen looked at that and said, ‘Hmm, we’ll just do something else,’” said Havens. Instead, they put bent nails through rope at one-foot intervals, and snagged a total of 34,408 derelict crab pots to the surface over six years.
Removing the traps cost $4.2 million in total. But according to the study in Scientific Reports, it resulted in a 27 percent increase in catch—roughly one extra crab in every working pot–for an economic benefit of $21.3 million over what would have happened had the abandoned pots remained in place.
“People will argue about the amount,” said Chris Moore, Virginia senior scientist for the Chesapeake Bay Foundation, who was not involved in the study. But “one of the great things about this study is that it attempts to commoditize what our losses are from this derelict fishing gear. We generally talk about these kinds of programs as doing good work, but we seldom get to quantify how they contribute dollars to the economy. This study starts to put the question in cost-benefit terms.”
At the moment, the recovery program has ended in Virginia because disaster-relief funding ran out. But this study obliges Virginia to ask whether “we should start putting money toward these programs so we will reap the benefit of a greater fishery later on,” said Moore. The same question ought to be debated in other fisheries, from lobsters in Maine to crabs in Southeast India, according to Havens and his co-authors.
Both the local and global benefit estimates in the study are based on the goal of recovering 10 percent of derelict pots. But what about the 90 percent of lost pots that would remain on the bottom? Researchers at VIMS have also tested a biodegradable escape hatch suitable for any pot in current use. It costs about $1 per pot and uses PHAs, (Polyhydroxyalkanoates), a family of naturally occurring biopolyesters, which marine bacteria break down over the course of a year. After that, any crab or lobster pot still on the bottom would be harmless.
Will watermen take up the escape hatch idea? It’s too soon to say, according to Havens, but he says he is already seeing changes in attitude about derelict pots.
This past summer, “I saw a crabber with a load of derelict traps in his truck, and I asked him about it. He said, ‘Oh some of my buddies were throwing them in the water. But I’m taking them to the dump.’ That wouldn’t have happened in the past.”