When fishing gear gets lost at sea in bad weather or is abandoned in the ocean when its useful life is over, it wreaks more havoc than most ocean plastic. This derelict gear continues to fish, or ghost fish. Nets have been getting lost since people first started fishing with them, but the problem is more serious than ever because the scale of fishing operations is enormous, and fishing gear is now made of durable, man-made materials that do not biodegrade. Plastic monofilament replaced hemp and cotton fibers in nets, and steel wire traps are now coated with vinyl. This gear lasts longer and kills longer regardless of whether they are under the control of a fisherman or not.
The worst ghost-fishing offenders are gill nets, lobster pots and crab traps. Gill nets are suspended vertically in the water with floats at the top and weights along the bottom edge. Gill nets can be up to two miles long and fifty feet tall. They can be set anywhere in the water column, from the surface to deep sea floor, and they are left in place (the “soak time”) from a few hours to a couple days. When nets are lost are abandoned in the water, they continue to fish. Fish caught in the net attract other fish looking for an easy meal and these also become entangled. Eventually, the weight of the catch sinks the net to the bottom. When the catch is eaten or decomposes, the net floats back up into the water column and resumes fishing.
During open fishing season lobster pots and crab traps sit on the bottom, connected to the surface by a rope attached to a float. When lost or abandoned, they continue to trap in open season as well as closed. These traps are self-baiting. Animals enter the trap to feed on what’s inside and become bait for the next crab, lobster or fish. Derelict traps and nets also damage the ocean bottom. They can smother bottom animals and plants, or, propelled by currents and dragged by boats they plow over reefs, snap off fragile coral and uproot seagrass.
Ghost gear kills indiscriminately. Sometimes they catch commercially valuable fish and can lead to overfishing. They often catch sea turtles, seals, birds and whales, endangered species included.
Fishermen don’t want to lose gear; lost gear is expensive to replace. But out in the deep sea with big nets in bad weather, the unexpected happens and fishing gear does get lost. Sometimes nets are intentionally left at sea. This is an easy, cheap way to dispose of fishing gear, and in some places carries no social stigma. It’s been illegal to dump fishing gear overboard since 1973 when the United Nations passed the International Convention for the Prevention of Pollution from Ships, or MARPOL. This doesn’t mean it never happens. An old sofa in an empty lot at the edge of town is visible; fishing gear thrown overboard out at sea isn’t.
There are huge gaps in our knowledge of ghost fishing because it happens beneath the sea’s surface: Where is the ghost gear? How much gear is out there? How many animals and what kind are they catching? The ghost fishing situation is further complicated because fishing regulations and gear vary from state to state and country to country.
Ghost fishing is a tough problem, but people are working hard to fix it as well as limit the bycatch, or unintended killing, of manned nets and traps. Pots and traps with escape panels fastened with “rot cords” or biodegradable twine allow animals to escape once the twine biodegrades. There are programs to retrieve lost pots and traps. In some ports fishermen can dispose of old nets for free so there is less incentive to leave them at sea. Financial incentives encourage fishermen to bring in derelict gear. Fishing gear can be located with GPS and transponders which makes losing it less likely. Tags can be attached to gear to identify the owner. Research is being done on using biodegradable fibers to make nets so if they are lost, they won’t be able to kill indefinitely. Pingers, which emit a high-pitched sound every few seconds can warn whales, dolphins and seals to stay away from nets. Organizations, like, with chapters around the world, work to detect nets, remove them, and raise awareness. Nets are found with sonar or reported by fishermen and divers. Skilled, technical divers or salvage companies remove the nets. It’s dangerous and expensive work.
It’s not simple removing ghost gear from the ocean, but occasionally derelict nets and traps wash ashore. Though dragging nets up and throwing them away isn’t always easy, it is doable. If you come across ghost gear on your shore, remove it. Enlist help from friends if you need it and stop the indiscriminate killing.
When you’re at the beach, remove the little stuff that has washed ashore too: the bottle caps, plastic forks, and broken pieces of mystery plastic. This is really easy to remove, especially if there is a BlueTube at your shore. Grab a bag from the BlueTube, fill it with plastic trash, throw it away. Don’t forget to add your extra clean, used plastic bags to the BlueTube so others can keep the shore clean and keep plastic out of the ocean too.