Net Losses Kill Sharks

September 26, 2005

Release from: Nature.com

Abandoned deep-sea fishing nets are killing large numbers of fish and sharks in the northeast Atlantic, report researchers after initial surveys of the area last month.

The warning comes from a joint project between Britain, Norway and Ireland that is examining the largely unregulated fishing in that area.

The researchers involved with the project, called DEEPNET, say the situation may warrant emergency measures that would close the fishery for six months while an improved management policy is put in place.

Up to 50 vessels have been operating in deep-water fisheries to the west and north of Great Britain and Ireland since the mid-1990s. These ships drop their nets into the deep waters of the Atlantic for three to ten days at a time. This efficiently picks up a large number of fish, but the process is wasteful: about half of the catch is unfit for human consumption by the time the nets are retrieved.

On top of this, the ships often lose or abandon their nets, which can be up to 250 kilometres long. This produces death traps on the bottom of the sea that continue to catch and kill fish and sharks.

Unwatched deeps

"There is no monitoring of what these vessels are fishing," says Dominic Rihan, one of DEEPNET's technical experts. "This has been going on since the 1990s and there are literally no data on this fishery; it is as if it doesn't exist."

The project was set up last March to collect data and draw international attention to the problem.

Scientists with the Centre for Environment Fisheries and Aquaculture Science (CEFAS), which works for the UK government, are starting a more extensive, 20-day survey this week. Their conclusions, to be released at the end of October, may help to prompt new regulations, say DEEPNET participants.

Long-term traps

Researchers from DEEPNET ran a net-retrieval operation last month. "Discardment is a big deal. We found huge amounts of gear basically abandoned," says Rihan. Some of the nets they found had been left there eight or nine months, he adds.

"Because there is little current the nets don't get tangled. Instead they fill, the fish degrade and the net empties and then fills up again," says Rihan.

The deep-water species targeted by these nets include the leafscale gulper shark (Centrophorus squamosus), which is particularly vulnerable to population loss because of its slow reproductive rate, and the Portuguese dogfish shark (Centroscymnus coelolepis). Other species of fish and shark are caught as by-catch, including rays, ling and deepwater red crab.

Changing the rules

Current European regulations focus on the size of the nets and the allowable catch. But there are no restrictions on how long the nets can soak in deep waters, or how many fish can be discarded from the nets.