A 40-feet-wide by 40-feet-deep ghost net was discovered off of Grand Cayman Island last month. Full of more than 30 dead sharks, fish, and other marine animals that had decomposed beyond recognition, the net was so heavy it took days to capture and remove from the water.

Unfortunately, ghost gear like this is all too commonly spotted, and can keep “fishing” for up to 600 years.

Ghost gear is the term for any abandoned fishing gear which continues to trap, harm, and kill marine life as it travels through the ocean. As of 2009, an estimated 640,000 tons of ghost gear was added every year to the oceans. This number is now undoubtedly worse.

In a vicious, interminable cycle, ghost nets and fishing gear indiscriminately trap anything in their path, thereby attracting all types of marine life including birds, turtles, sharks, seals, sea lions, and fish; predators and prey alike. Gill nets, such as the one recently discovered, are the deadliest of all gear, and inexpensive to replace — so often they’re just abandoned. In their path of destruction they catch some of the most vulnerable species, like the endangered Olive Ridley turtle.

A recent international report by World Animal Protection (WAP) found that over 90% of pollution encountered by marine life is plastic. Ghost gear is a large part of this; in fact, 71% of marine animal entanglements involve plastic ghost gear. Some plastics can last for 600 years in water, causing danger and harm to animals through drowning, wounds, and ingestion. 79% of entanglement cases end with pain and/or death for the animals. A non-decomposing gill net attached to plastic is a horrible prospect for marine life.

45% of marine mammals on the International Union for the Conservation of Nature (IUCN) Red List of Threatened Species have been affected by ghost gear. Illegal fishing nets, unmonitored gear, and inoperative traps are an increasing threat to the marine ecosystem.  Illegal, unreported, and unregulated (IUU) fishing makes up between 20-32% of the US imports. 31% of fish stocks are overfished.

Initiating gear tracking and removal policies, mandating practical steps toward cleaning up the ocean, and using biodegradable materials are the bare minimum needed right now. But the fishing industry needs to commit to this. And biodegradable materials don’t remain in the water as long as other plastics, but they still can harm marine animals. The most certain way to make a lasting change would be to drastically reduce the amount of gear that enters the ocean overall, whether the material be biodegradable or not. Gill nets should be the first to go.