"(Ghost gear) is like a zombie in the water," Greenpeace marine biologist and oceans expert Thilo Maack told AFP. "Nobody takes out the catch, but it's still catching."

The report found that there is an alarming amount of this deadly plastic gear in the oceans. Around 640,000 tonnes of it enter the world's oceans every year, around the same weight as more than 50 thousand double decker buses.

While fishing gear represents 10 percent of ocean plastic overall, it makes up a much larger proportion of large plastic pollution. In some areas, it contributes the "vast majority of plastic rubbish."

• It makes up around 70 percent of plastics more than 20 centimeters (approximately 8 inches) large floating on the ocean's surface; buoys alone account for 58 percent.
• Fishing nets make up 86 percent of the large plastics in the Great Pacific Garbage Patch.
• Fishing equipment makes up more than 85 percent of the plastic pollution on sea mounts, ocean ridges and the sea floor.
• Fishing industry debris comprised 60 percent of six tonnes of garbage collected from the remote Henderson Island in the Pacific Ocean.

This is a major problem for marine life. A single ghost fishing net killed around 300 sea turtles in Mexican waters in 2018. And every year, ghost gear kills more than 100,000 whales, dolphins, seals and turtles, UK-based charity World Animal Protection told AFP.

"It's a huge problem because as they are initially set to trap and kill marine wildlife, they will do that for as long as they are in the oceans," Greenpeace Africa's campaigner Bukelwa Nzimande, 29, told AFP.

Ghost gear spreads for a variety of reasons, but mostly because of overcrowded fisheries, overfishing, and illegal or unregulated fishing, the report found. There is also no legal framework currently in operation to protect marine life in international waters.

Greenpeace UK oceans campaigner Louisa Casson spoke to the scope of the problem, according to The Guardian:

"Ghost gear is a major source of ocean plastic pollution and it affects marine life in the UK as much as anywhere else.

"The UK's waters do not exist in a vacuum as oceans have no borders. The world's governments must take action to protect our global oceans, and hold the under-regulated fishing industry to account for its dangerous waste. This should start with a strong global ocean treaty being agreed at the United Nations next year."

The ocean treaty is one of three recommendations Greenpeace issued to address the problem.

The Global Ocean Treaty, which is supposed to be agreed upon by 2020, would allow governments to create ocean sanctuaries in at least 30 percent of international waters by 2030.

Greenpeace also called for following the best practices suggested by the Global Ghost Gear Initiative and fighting marine pollution through global and regional organizations.