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Scientists investigating bizarre deep-sea communities living around methane "seeps" off New Zealand's east coast say many have been damaged by bottom trawling.
"Every single one of the seep sites that we went to had evidence of trawling damage," said an American researcher, Amy Baco-Taylor, of Woods Hole Oceanographic Institution in the US, co-leader of the expedition with New Zealander Ashley Rowden.
New Zealand has been identified by an international census of marine life as a high-priority region for research into "chemosynthetic" ecosystems, such as hot hydrothermal vents and cold methane seeps, where organisms take energy from methane or sulphide chemicals instead of sunlight.
The researchers, who visited eight seeps along the continental shelf to the east of the North Island, said their expedition showed the extent to which the bottom-dwelling creatures face "serious threats from human activities".
"We saw trawl marks going right through the seeps, we found lost fishing gear on the seeps, and one of the seep sites had a large area of coral rubble nearby that had obviously been damaged by trawling," said Dr Baco-Taylor.
"This is significant, because if we find that these sites have a unique fauna, and they're being destroyed by trawl damage, it could be a whole community of organisms that is going to be affected".
The 21 scientists on the New Zealand research vessel Tangaroa took extensive video footage of the sites in an effort to gather information without further damaging the organisms.
The Tangaroa docked back in Wellington this week as a proposal for a global ban on bottom trawling on the high seas entered its final days of debate at the United Nations in New York, where many nations have argued the technique causes damage to extremely slow-growing ecosystems.
The UN debate - where Australia and New Zealand are calling on the UN to adopt an immediate and binding moratorium - will finish next week.
Any agreement will likely go to the UN General Assembly for a decision on December 7.
Bottom trawling is a fishing method in which a big net weighed down by massive steel gates is dragged along the ocean floor to scoop up fish, a practice environmentalists say causes irreversible damage to sensitive deep-sea ecosystems.
Fishing-industry advocates say trawling affects only a small percentage of the ocean floor, but critics of the method say fishers target the richest part of the sea floor, particularly coral reefs and sea mounts.
Dr Baco-Taylor said one question that interested the researchers was the extent to which the rich ecological systems on the seep sites attracted the deep-ocean fish targeted by fishers.
Dr Rowden, from the National Institute of Water and Atmospheric Research (Niwa), which operates the Tangaroa, said he believed people would be surprised by how much life was present in and around the seeps.
"The damage demonstrates that seeps are vulnerable to disturbance."
Most seep sites were quite small, but the scientists saw evidence of fishing practices on the seabed in the vicinity of the seeps.
"The photographs reveal trawl marks or lost wire or nets, and on two locations we actually had fishing boats around us as we were doing our own sampling," Dr Rowden said.
There was enough evidence to justify protecting the sites of methane seeps "at least until we find out more about distribution of these sites, and more properly assess what the extent of their vulnerability is".
- NZPA
