It's a small victory for a politician used to much bigger tussles: but Shane Jones has won the first fight of his new job by helping to save the humble Tongan sea cucumber.

Remember Shane Jones? The fiery Labour politician who quit Parliament in April to take up a newly-created role roaming the Pacific as New Zealand's fishing envoy/ambassador to several small nations? The headlines may have gone, but Jones hasn't been quiet. The Tongans are now banning the harvesting, processing and exporting of sea cucumbers, or beche-de-mer, for the next five years. And next up he will wade into decisions about how the Pacific Islands carve up the $8 billion a year Pacific tuna stock without decimating it. These debates are the sort in which Jones could play a vital role, says Glenn Hurry, a senior Pacific fishing official. "He is quite effective. He's the type of person the region needs."

With 60 per cent of New Zealand's $600 million a year aid budget going to the Pacific and around $70 million to fisheries, Jones has some weight. "I want to be a friendly but firm face," he says. "It's not an amount to be sneezed at, and it's not unreasonable for us to be firm."

So first came the tasteless sea cucumber, believed by Asians to be good for sexual health, tendinitis and arthritis.

Now tuna. Jones, who once knocked iwi and hapu heads together in the early days of the Maori Fisheries Commission, has to do the same with Pacific nations over the lucrative migratory tide of skipjack tuna, which ranges from Papua New Guinea past French Polynesia and back toward New Zealand.

"As well as being our ambassador to Mauritius and the Seychelles and and now high commissioner to the bankrupted Pacific republic of Nauru, Jones is New Zealand's representative on several fishing agencies that effectively control the industry in the Pacific. These bodies, he says, are "a reminder of human nature".

"It is a reminder that when you have rivalry, the only way forward is to find common ground, or you are condemned to pitting forces against each other."

Big-eye tuna is down to 20 per cent of its original spawning biomass, or, thinks Jones, below 16 per cent - in layman's terms, nearing collapse.

Pacific bluefin is worse while yellowfin is around 37 per cent. Skipjack looks healthy at 50 per cent.

Hurry, who until earlier this year headed the Pacific fishing commission and before that ran Australia's fisheries agency, says tuna is a big problem looming".

He wants Jones to become a bigger player.

"A guy with Shane's skills and abilities as an orator might make a difference. He is someone who can open political doors."

Jones faces balancing conservation issues against pressure from bigger nations and industry on the smaller island countries - some of whom only make money by selling off their fishing rights - to ignore ecological issues and chase the dollar.

"There is so much pressure on the Pacific islands that the resource will disappear in a nanosecond," says Jones, who has to get everyone to play by the rules.

"The world will not take the Pacific seriously if there is evidence that the resource rules are being broken here."

But he has faith in the fishing industry is not in a race to the bottom.

"Any industry is always going to have outliers, any industry is going to have shenanigans, whether it is cutting trees, milking cows, extracting minerals, or harvesting fish.

"There will always be egregious elements.

"The investment in fishing is too vast now to see it "turn to fiscal dust" by wiping out the resource they depend on.

"I don't believe they are dedicated to catching the last fish."