green and sustainable business

The ocean ghost in the machine

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There’s the Eastern Garbage Dump, an assemblage of trash the size of Texas floating in the Pacific Ocean and there’s “ghost fishing” yet another assault on the our water planet’s oceans.ghostfishing2

Large amounts of fishing gear lost at sea or abandoned by fishers are damaging the marine environment, impacting fish stocks through what is known as ghost fishing and posing a hazard to ships, according to a report from the UN Food and Agriculture Organization (FAO) and UN Environment Program (UNEP).

“There are many ‘ghosts in the marine environment machine’ from over-fishing 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,” says Achim Steiner, UN Under-Secretary General and UNEP Executive Director. “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.”

This problem is getting worse because of the increased scale of global fishing operations and the introduction of highly durable fishing gear made of long-lasting synthetic materials.

The 139-page report estimates that abandoned, lost or discarded fishing gear in the oceans makes up around 10 percent (640,000 tons) 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, the report says, 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 – or 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 vessels.

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

In the past, poorly operated drift nets were the prime ghost fishing 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, 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.

The total input of marine litter into the oceans per year has been estimated at approximately 6.4 million tons annually, of which nearly 5.6 million tons, or 88 percent, comes from merchant shipping.

About 8 million items of marine litter are thought to enter the oceans and seas every day, with about 5 million (63 percent) comprising solid waste thrown overboard or lost from ships.

It’s been estimated that  more than 13,000 pieces of plastic litter are floating on every square kilometer of ocean. In 2002, 6 kg of plastic was found for every kilogram of plankton near the surface of a gyre point in the central Pacific, the Eastern Garbage Dump, where debris collects.

Mass concentrations of marine debris in high seas accumulation areas, such as the equatorial convergence zone, are of particular concern, the UN says. In some such areas, rafts of assorted debris, including various plastics; ropes; fishing nets; and cargo-associated wastes such as dunnage, pallets, wires and plastic covers, drums and shipping containers, along with accumulated slicks of various oils, often extend for many kilometers.

“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,” says Ichiro Nomura, FAO Assistant Director-General for Fisheries and Aquaculture. “Strategies for addressing the problem must occur on multiple fronts, including prevention, mitigation, and curative measures.”

Solving this problem seems difficult to impossible. It’s tough to monitor and regulate what happens in the middle of the ocean, but the report takes a stab by recommending:

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. 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.

Also, 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.

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.

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. 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 not to punish but to improve awareness of potential hazards and increase the opportunity for gear recovery.

The FAO/UNEP report is a likely topic as nations prepare to gather in for the World Oceans Conference in Manado, Indonesia next week (May 11-15).

The ocean is big and a little trash and debris, or even a lot, won’t hurt much because it’s a self-cleaning system, right? Guess again, slappy.


Written by William DiBenedetto

6 May, 2009 at 10:19 am

Posted in environment, fishing, ocean, ports

Tagged with , ,

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