What is ghost fishing?

Ghost fishing occurs when nets, ropes, lines and other fishing equipment, including crab pots and lobster traps, is discarded in the ocean, either intentionally or accidentally. Ghost nets are made from synthetic materials, including nylon, polyester and plastic compounds, and can drift thousands of kilometres away from their entry point in the ocean.

The increase in commercial and recreational fishing, use of synthetic materials and other marine debris trapped in nets and lines has exacerbated the problem. Abandoned fishing gear drifts in the water and becomes snagged on submerged rocks, coral reefs or the seabed, where it continues to trap sentient marine life, including fish, cetaceans, turtles and other marine animals. Whales and dolphins may become entangled in the nets and die from exhaustion and suffocation in their struggle to get to the surface to breathe.

How many ghost nets are there in the ocean?

Between 500,000 and 1,000,000 million tonnes of fishing gear are lost or abandoned in the ocean every year. Discarded ghost nets, lines and ropes comprise nearly 46% of the plastic in the Great Pacific Garbage Patch. Only 10% of plastic waste in the ocean is from fishing gear (WWF 2020). Most plastic waste in the ocean comes from the land.

Entanglements in marine debris and other non-fishing-related plastic waste pose a threat to marine organisms, as do climate change, overfishing and ocean acidification. The issue is complex, with no easy answer.

Ghost nets and sea turtles

Seven species of sea turtle can be found swimming in our beautiful blue global ocean, with their IUCN Red List status ranging from ‘Data Deficient’ to ‘Critically Endangered’.

Two species – Eretmochelys imbricata (Hawksbill Sea Turtle) and Lepidochelys kempii (Kemp’s Ridley Sea Turtle) are ‘Critically Endangered’.

One species – Chelonia mydas (Green Sea Turtle) is ‘Endangered’

Three species – Dermochelys coriacea (Leatherback Sea Turtle), Caretta caretta (Loggerhead Sea Turtle) and Lepidochelys olivacea (Olive Ridley Sea Turtle) are ‘Vulnerable’

One species – Natator depressus (Flatback Sea Turtle) is ‘Data Deficient’.

While cetaceans are at risk of entanglement in ‘active’ and ‘passive’ fishing gear (see Bycatch & Incidental Capture of Cetaceans under Impacts), sea turtles are the marine animals most often caught in discarded fishing gear. All 7 species of sea turtle are affected by entanglement, compared to 31% of whale species and 25% of seabird species (Kuhn et al. 2015).

Documented reports of sea turtle entanglement

Sea turtles are air-breathing marine animals and must come to the surface to breathe. When trapped in abandoned fishing gear drifting aimlessly through the ocean, the sea turtles are dragged along with the net, rope or line, cannot get to the surface, and drown.

In August 2018, about 300 Lepidochelys olivacea (Olive Ridley Sea Turtle) individuals were found dead off the southern coast of Mexico, trapped in an abandoned illegal fishing net. The turtles were attempting to embark onto land for their annual egg-laying season.

Weeks earlier, 102 Lepidochelys olivacea (Olive Ridley Sea Turtle), 6 Eretmochelys imbricata (Hawksbill Sea Turtle) and 5 Chelonia mydas (Green Sea Turtle) individuals were found entangled in ghost nets, although it is unknown if the animals were already deceased.

Are sea turtles at risk of extinction from ghost nets?

Although there are many documented instances of sea turtles getting trapped in ‘active’ and ‘passive’ fishing gear, this is not the reason some species of sea turtle are threatened with extinction. Historically, sea turtle populations have decreased dramatically from poaching and over-harvesting of eggs. Ghost nets and bycatch mortality are hampering sea turtle recovery, but is not the cause of their historical decline, or the only threat they face today.

REFERENCES:

Global Ghost Gear Initiative (GGGI), https://www.ghostgear.org/, accessed 28.07.2021

IUCN Red List. https://www.iucnredlist.org/, accessed 28.07.2021

Kühn, S., Rebolledo, E. L. B., & van Franeker, J. A. (2015). Deleterious effects of litter on marine life. In Marine anthropogenic litter (pp. 75-116). Springer, Cham. https://doi.org/10.1007/978-3-319-16510-3_4

World Animal Protection (2014), Fishing’s phantom menace – how ghost fishing gear is endangering our sea life, published by World Animal Protection International, https://www.worldanimalprotection.org/sites/default/files/media/int_files/sea-change-campaign-tackling-ghost-fishing-gear_0.pdf

WWF International (2020), Stop ghost gear the most deadly form of marine plastic debris, published by WWF – World Wide Fund for Nature, https://europe.nxtbook.com/nxteu/wwfintl/ghost_gear_report/index.php