'It's not fishing, it's extinction'

This ancient piece of coral was tangled in a fishing net and dumped by the boat who dragged it up.

Bottom-trawling destroys the ocean floor, says Greenpeace, which has released a striking photograph to illustrate the damage wrought by the practice.

The photo, taken in 2003 in the Tasman Sea off the North Island, shows fishermen trying to untangle a huge piece of "gorgonian" coral the environmental organisation says is more than 500 years old.

Greenpeace oceans campaigner Shirley Atatagi-Coutts said: "This isn't fishing, this is extinction."

Spokesman Dean Baigent-Mercer asked why the practice was legal when it was illegal to clearfell native forests on land.

The organisation heard of the photo's existence and obtained it under the Official Information Act from the Ministry of Fisheries.

The boat was New Zealand-registered but Greenpeace was not told its name or who operated it.

Mr Baigent-Mercer said Greenpeace wanted an end to bottom-trawling in international waters and the Government to listen to scientists about its impact on domestic waters.

The photo was one of the best images globally showing the practice's impact, and it was being released as a UN meeting on ocean issues began in New York.

Mr Baigent-Mercer said bottom-trawling involved large underwater nets up to 40m wide that were dragged along the sea floor.

Huge chains or rollers attached to the front of the nets destroyed everything in their path, including coral forests, sponges, sharks, giant crabs, boulder fields and rocky reefs.

The method is the most common way of fishing in New Zealand's exclusive economic zone and internationally.