Wellington, Nov 26 NZPA - There should be a halt to commercial catching of the threatened longfin eel, says a group concerned about the species' future.

A coalition of environmental groups, Maori groups and Massey University researchers are gathering signatures for a petition asking for a moratorium on commercial harvesting of the eel.

The eel had the same risk classification as the great spotted kiwi but could still be caught by commercial fishers under the Quota Management System, managed by the Ministry of Fisheries, the group said in a statement.

Massey University freshwater ecologist and senior lecturer Dr Mike Joy said the earnings from the eels export industry were negligible to the economy and were not worth the damage.

"The commercial fishery is responsible for depleting a threatened native species, Dr Joy said.

Forest & Bird advocacy manager Kevin Hackwell said eels migrated to sea and swam thousands of kilometres to undertake a mass spawning event, after which they died.

"It takes many decades -- up to 100 years -- for female longfins to mature to breeding age. They are at constant risk of capture all that time, every eel caught is one less which will breed," he said.

The larvae drift on ocean currents, changing into glass eels once they reach New Zealand's rivers. They turn into darker elvers as they swim upstream.

"It is not acceptable any more to harvest native birds or marine mammals for food," Mr Hackwell said.

"Yet they are commercially harvesting a native fish species to the point of collapse."

The eels were already struggling because of a decline in water quality.

The groups backing the petition included the newly formed Manaaki Tuna (the Massey University Tuna Research and Restoration Group), Forest & Bird, Greenpeace, the Environment and Conservation Organizations of NZ (ECO), and several iwi groups.

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