A bounty program to capture American Iguanas has been launched in Fiji.

American Iguanas, which can grow up to two metres and weigh nine kilograms, aren't native to the region and cause damage to indigenous ecosystems.

Islanders will receive a reward of $US5 dollars for every adult iguana handed in over the next four months.

The Biosecurity Authority of Fiji and Nature Fiji-MareqetiViti are hoping the program will eradicate the pest.

Director of Nature Fiji-MareqetiViti, Dr Richard Watling, has told Radio Australia's Pacific Beat the iguanas are posing a major problem in Fiji.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Listen Duration: 4 minutes 18 seconds 4 m 18 s Dr Richard Watling speaks to Pacific Beat ( Pacific Beat ) Download 2 MB

"This iguana has arrived and become established on one small island in Fiji," he said.

"This is the first island in the Pacific where...it is expanding very rapidly.

"This is the bridgehead to some of the most vulnerable and isolated floras in Oceania."

Dr Watling says the program is a trial and not necessarily the solution.

"Bounty programs in general don't have a very good reputation for being sustainable," he said.

"This is going to be one which is purely for the next four months over the breeding season when these animals are most conspicuous."

Dr Watling says the iguana's breeding season will make them easier to spot as they move around more when looking for a mate and laying eggs.

He says there are limited resources available in Fiji for tackling the issue.

"If this species was gaining a foothold in Australia or New Zealand there would be very major resources immediately but we just don't have those sorts of resources here," he said.

"We would like to see to what degree the villagers and the landowners can get involved and benefit from doing some control work."