The problem of abandoned fishing gear and its effects on marine life deserve greater attention.
Here’s a horror story for Halloween. Right now, in unlit waters across the world, fish, crabs and other marine life are being drawn into nets and traps by the dead and decomposing bodies of their comrades. There they will stick, struggle and tangle, until they, too, become unwitting bait and continue the circle of death. Old fishing nets, you see, never die. They just drift away.
The problem of ghost fishing, as it is known, goes largely unnoticed, but some of this dead gear catches and kills more sea life than it did when it was alive and in active use. Reliable data on the scale of the problem are scarce, but some estimates suggest that the nets can remove up to 30% of the landed catch of certain fish species.
It is said that we know more about the surface of the Moon than about the bed of the sea. Perhaps we are afraid of what we will find there if we look too hard: wrecks of gill nets, entangling nets, pelagic and demersal longlines, lobster and crab pots, seine nets, trawl-net fragments and the sinister-sounding fish aggregating devices — buoys or floats, tethered to concrete blocks, around which fish tend to congregate.
Some of this fishing gear is lost and some is abandoned in rough weather. Much is simply discarded by fishers with nowhere to stow it, who are fishing where they should not be, or who just want to avoid the expense and hassle of disposing of it properly. Most of this gear sinks to the bottom. It becomes a hazard, to boats and divers. And much of it continues to catch and kill, long after it has been forgotten.
Take the coastline of Louisiana, a US state that is home to its fair share of spooky tales. Each of the 1,800 or so professional crab fishers who work there loses about 250 traps every year. Each abandoned trap, a crude wire cage, is reckoned to catch and kill a blue crab (Callinectes sapidus) every two weeks. That is 12 million crabs a year, or 2 million kilograms of crab meat — about US$4-million worth — along a single stretch of coastline (J. A. Anderson and A. B. Alford Mar. Pollut. Bull. 79, 261–267; 2014). Ghost crab traps snare other creatures too: spotted sea trout, diamondback terrapins and river otters among them.
Although the world organizes regular conferences to address the threat of orbiting space junk, action on the danger of ghost fishing tends to be left to volunteers. Louisiana law allows a ten-day period each year when citizens can drag derelict fishing gear from the water. In two sessions — 2012 and 2013 — volunteers recovered a total of 3,607 ghost crab traps. More than 65% of them had caught something. The actions of such volunteers are admirable but they are not enough. The fishing industry and those who profit from it must take more responsibility.
Earlier this year, Eric Gilman, a fisheries scientist at Hawaii Pacific University in Honolulu, published a survey of international efforts to track and control ghost fishing (E. Gilman Mar. Policy 60, 225–239; 2015). Of the 19 global and regional bodies (from the International Whaling Commission down to the South East Atlantic Fisheries Organization) that he identified as being in a position to intervene, just 4 had an explicit mandate to monitor and reduce the problem. Almost half did not even collect data on lost gear. The 12 organizations that have introduced measures to help prevent and reduce ghost fishing have not used all the options available to them.
All ghost stories are more chilling in the dark. The problem of abandoned, lost and discarded fishing gear deserves more attention and more action. For unlike many gruesome stories you will hear this weekend, this one is true.
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Ghost story. Nature 526, 610 (2015). https://doi.org/10.1038/526610a