To Catch More Crabs, Catch Lost Crab Traps

Every year, vast quantities of fishing gear is lost at sea - from nets to lines, pots and traps. The traps lay derelict on the seafloor, catching wandering crustaceans, which, once caught, may not escape and could die imprisoned in the discarded trap. This can have a huge impact on populations - for the species the trap was intended for, and for others.

The traps are primarily lost during storms, during which they can be ripped from their tether or can loose their surface marker, rendering them incredibly difficult to find. When baited, these traps can attract piles of crabs that flock from afar to catch a free meal. But even when empty, the structure these pots provide in an otherwise barren landscape attracts inhabitants.The number of animals caught in a trap varies hugely with trap design and with species interactions, as some defend their territory, reducing the number of successful newcomers. Despite this, they remain effective and are responsible for huge losses from crustacean populations and from fisheries.

Just how huge, has been demonstrated by scientists from William & Mary's Virginia Institute of Marine Science. In a six-year program to remove lost pots in Chesapeake Bay, commercial crabbers were employed to find and recover derelict gear over the winter - outside of their fishing season. Together, they removed some 34,000 derelict crab pots and - at the same time - harvests increased dramatically.

"We estimate that crabbers harvested about 60 million more crabs due to the ghost-pot removals," says study co-author Donna Bilkovic. "That's one extra blue crab each time a pot is retrieved - crabs that would have otherwise been captured or attracted to the now absent derelict gear."

But was it worth the cost of employing crabbers to catch lost traps? The project cost $4.2 million to run, and generated over $21 million in harvest value. It's a no-brainer. "The benefits far outweighed the program's total cost," says Andrew Scheld, another of the study's authors.

Ghost gear is most likely to accumulate in areas that are heavily fished. The study showed that by focusing recovery efforts on these areas, the return on investment could be even greater.

Chesapeake Bay is the largest estuary in the US and one of the world's major shellfish fisheries, but it's not the only area affected by derelict gear. Wherever fishing takes place, lost pots and traps are a problem.

Ghost gear is a global phenomenon, but it needn't stay that way. Removing even 10% of derelict pots and traps from major crustacean fisheries around the world could increase landings by nearly 300,000 tonnes, which would boost profits by $800 million a year. With that kind of financial incentive, ghost gear should soon be a thing of the past.