The Whale Shark is the biggest fish in the world, and has been assessed as 'Vulnerable'.
But each year many are lost when they get tangled in the nets set by Tuna fishers, targetting the fish which gather under them.
The commission's new rule means that can no longer be done, and it also requires fishing vessels to try and free any whale sharks accidentally caught.
Gerry Leape is the head of the Pew delegation which is attending the Commission's annual meeting underway in Manilla, and he explained the issue to Pacific Correspondent Campbell Cooney.
Presenter: Campbell Cooney
Speaker: Gerry Leape, Pew Environment Group
LEAPE: Fishermen noticed about 50 years ago that schools of tuna tend to swim beneath large objects. At first it was sticks and trash and plastic and other things, then they noticed they'd swim underneath dolphins and other cetaceans, and then in the region they noticed that oh gosh, they actually swim below whale sharks, and so what they do is they take these very large nets, they circle the whale sharks, and they pull it up, pull it closed like a purse and it catches the tuna that are swimming below the whale shark, but it also traps the whale shark, because these nets are sometimes hundreds of yards wide, and so as they draw the purse closed the whale sharks gets entangled in the nets. Our concern was we really shouldn't be allowing this sort of fishing method to be used and the Fisheries Commission needed to take action.
COONEY: Do we have any sort of figures about what sort of numbers of whale sharks might have been lost because of this over the years?
LEAPE: It's at least dozens probably, over ten years they don't sound like big numbers, but when you have an animal that's extremely vulnerable and is down to low population numbers, just taking a few animals can have a significant impact on the stock, and that's why the government of Australia took up this fight last year and made a real valiant effort to try and get the commission to agree last year to this measure, but they didn't succeed ultimately, but they worked hard over the interim and we've supported them and helped work with other countries to come to the point where we're able, they were able to agree to it. Not only they will ban the deliberate encirclement of whale sharks, but also if there's an incidental, if they actually circle, they brought up their net and say gosh, we didn't know there was a whale shark in it, then they will be forced to use best practices to release it alive.
COONEY: And that could include letting their catch go?
LEAPE: Right, right.
COONEY: Is there a concern that perhaps while the rules might be put in place that they could be hard to police? That you could still catch them, you could still kill them and you'd just would never find out about it?
LEAPE: Well our hope is that because in this region there's 100 per cent observer coverage, so there are independent observers on every boat, that that will help minimise the misuse or the lack of use of this new rule. And so we're hopeful that that will help expedite implementation.
COONEY: It's one of the issues that's certainly being discussed at the meeting, and you mentioned of course that the whale sharks are like a big living fish aggregation device. That has been a major issue of concern for the Fisheries Commission and for fisheries. Has there been any decisions or any sort of other things that you guys are encouraged about that's happened at that meeting, or I know it's not about to end, but it will hopefully happen before it finishes?
LEAPE: Yes we're hopeful that countries can come to agreement on a system that will begin to manage all FADs. They are working assiduously on it today and we're hopeful they can come to agreement that not only would require them to identify how many FADs are out there, but also begin to take actions to control the numbers of FADs that are there and assess their impacts and try and minimise the adverse impacts.
COONEY: What about conservation of other fish and animal species?
LEAPE: Those discussions have been difficult and they're still ongoing. But so far countries have been unwilling to make significant compromises in terms of catching other tunas. Well hopefully that will change today, but they need to wind it up pretty soon, because they need to get these catch limits in place for the other tropical tuna species. The Big Eye, which is the most vulnerable, but also Yellow Fin and Skipjack. The Big Eye is caught also in these purse seiners, juvenile Big Eye when they're trying to catch the Skipjack. And they can reduce not only the catch of juvenile Big Eye, but also the long-liners who are catching the adults.