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Ghost nets hurting marine environment

Abandoned, lost or otherwise discarded fishing gear is impacting fish stocks and poses a hazard to boats

Photo: U.S. National Oceanic and Atmospheric Administration
A sea turtle tangled in an abandoned or lost fishing net.
6 May 2009, Rome - Large amounts of fishing gear lost at sea or abandoned by fishers are hurting the marine environment, impacting fish stocks through "ghost fishing" and posing a hazard to ships, according to a new report jointly produced by the UN Food and Agriculture Organization (FAO) and UN Environment Programme (UNEP).

According to the study, the problem of abandoned, lost or otherwise discarded fishing gear (ALDFG) is getting worse due to the increased scale of global fishing operations and the introduction of highly durable fishing gear made of long-lasting synthetic materials.

The report estimates that abandoned, lost or discarded fishing gear in the oceans makes up around 10 percent (640 000 tonnes) of all marine litter. Merchant shipping is the primary source on the open sea, land-based sources are the predominate cause of marine debris in coastal areas.

Most fishing gear is not deliberately discarded but is lost in storms or strong currents or results from "gear conflicts," for example, fishing with nets in areas where bottom-traps that can entangle them are already deployed.

The main impacts of abandoned or lost fishing gear are:

  • continued catches of fish -- known as "ghost fishing" -- and other animals such as turtles, seabirds, and marine mammals, who are trapped and die;
  • alterations of the sea-floor environment; and
  • the creation of navigation hazards that can cause accidents at sea and damage boats.

Gill nets, fishing pots and traps are most likely to "ghost fish," while longlines, are more likely to ensnare other marine organisms and trawls most likely to damage sub-sea habitats.

Ghost fishing

In the past, poorly operated drift nets were the prime culprits, but a 1992 ban on their use in many areas has reduced their contribution to ghost fishing.

Today, bottom set gill nets are more often-cited as a problem. The bottom edge of these nets is anchored to the sea floor and floats are attached to their top, so that they form a vertical undersea wall of netting that can run anywhere from 600 to 10 000 meters in length. If a gillnet is abandoned or lost, it can continue to fish on its own for months - and sometimes years - indiscriminately killing fish and other animals.

Traps and pots are another major ghost fisher. In the Chesapeake Bay of the United States, an estimated 150 000 crab traps are lost each year out of an estimated 500 000 total deployed. On just the single Caribbean island of Guadeloupe, about 20 000 of all traps set each year are lost each hurricane season - a loss rate of 50 percent. Like gill nets, these traps can continue to fish on their own for long periods of time.

Solutions

"The amount of fishing gear remaining in the marine environment will continue to accumulate and the impacts on marine ecosystems will continue to get worse if the international community doesn't take effective steps to deal with the problem of marine debris as a whole. Strategies for addressing the problem must occur on multiple fronts, including prevention, mitigation, and curative measures," said Ichiro Nomura, FAO Assistant Director-General for Fisheries and Aquaculture. He also noted that FAO is working closely with the International Maritime Organization (IMO) in its ongoing review of Annex V of the International Convention for the Prevention of Pollution from Ships (MARPOL) as regards fishing gear and shore side reception facilities.

Achim Steiner, UN Under-Secretary General and UNEP Executive Director, said:" There are many ‘ghosts in the marine environment machine' from overfishing and acidification linked with greenhouse gases to the rise in de-oxygenated ‘dead zones' as a result of run off and land-based source of pollution. Abandoned and lost fishing is part of this suite of challenges that must be urgently addressed collectively if the productivity of our oceans and seas is to be maintained for this and future generations, not least for achievement of the UN Millennium Development Goals".

The FAO/UNEP report makes a number of recommendations for tackling the problem of ghost nets:

Financial incentives.  Economic incentives could encourage fishers to report lost gear or bring to port old and damaged gear, as well as any ghost nets they might recover accidentally while fishing.

Marking gear. Not all trash gear is deliberately dumped, so marking should not be used to "identify offenders" but rather better understand the reasons for gear loss and identify appropriate, fishery-specific preventative measures.

New technologies.  New technologies offer new possibilities for reducing the probability of ghost fishing. Sea-bed imaging can be used to avoid undersea snags and obstacles. Fishing equipment can be expensive, and many fishers often go to great lengths to retrieve lost gear. Technology that makes doing so easier can help. Using GPS, vessels can mark locations where gear has been lost, facilitating retrieval, and transponders can be fitted to gear in order to do the same. Similarly, improvements in weather monitoring technology can be used to help skippers avoid deploying nets when very bad weather is imminent.

Just as new synthetic and other materials used in fishing gears have contributed to the ADLFG problem, they can also help solve it. Work is underway to speed up the commercial adoption of durable gear components that incorporate bio-degradable elements. For example, in some countries fish traps and pots are constructed with a biodegradable "escape hatch" that disintegrates when left under water too long, rendering the trap harmless. As this would not necessarily reduce the levels of debris, a reporting and retrieval system should also be adopted.

Improving collection, disposal and recycling schemes.  It is necessary to facilitate proper disposal of all old, damaged and retrieved fishing gears, according to the report. Most ports do not have facilities on site that allow for this. Putting disposal bins on docks and providing boats with oversized, high-strength disposal bags for old fishing gear or parts thereof can help remedy this.

Better reporting of lost gear.  A key recommendation of the report is that vessels should be required to log gear losses as a matter of course. However a "no-blame" approach should be followed with respect to liability for losses, their impacts, and any recovery efforts, it says. The goal should be to improve awareness of potential hazards and increase the opportunity for gear recovery.

The report discusses a number of other measures that could help, as well.

"Clearly solutions to this problem do exist, and our hope is that this report will prompt industry and governments to take action to significantly reduce the amount of lost or abandoned fishing gear in the marine environment," said Nomura.

The new report comes as nations are set to gather in for the World Oceans Conference in Manado, Indonesia (11-15 May 2009), where the issue of realizing healthy marine environments will figure high on the agenda.