'Ghost fishing' threat

Lost or discarded fishing nets can continue to catch fish for years and are a growing threat to the planet's marine ecosystem, according to a United Nations report released last Wednesday.

"The report estimates that abandoned, lost or discarded fishing gear in the oceans makes up around 10 per cent of all marine litter," said a statement from the UN Environment Programme.

The study, co-authored by the UN's Food and Agriculture Organisation (FAO), said the problem was getting worse due to the growing scale of global fishing and the use of fishing gear made of increasingly durable materials.

Among the main culprits are bottom set gill nets, which are anchored to the sea floor and fitted with floats, forming an undersea wall of netting that can stretch several thousand metres.

"If a gill net is abandoned or lost, it can continue to fish on its own for months - and sometimes years - indiscriminately killing fish and other animals," the UNEP statement said.

The report also cited the case of devices such as crab traps, which in some regions are lost by hundreds of thousands with each hurricane season.

The UN study listed a number of measures to curb the trend such as financial incentives for fishermen to report lost gear, marking technology, improved disposal schemes and the use of bio-degradable elements in fishing gear.