The Greenpeace flagship Rainbow Warrior has spent the past few days hosting all the key players in one of the Indian Ocean's prime tuna hubs – Port Louis in Mauritius.

This is a welcome turnaround.

Just a few days ago it didn’t look like we would be able to welcome these important contacts at all. Initial reluctance by the authorities to allow the Rainbow Warrior melted away once we had a chance to explain that we are visiting the Indian Ocean simply to listen, learn and understand this region that is so central to the global tuna trade.

Over the past few days we’ve talked to artisanal fishermen, NGOs, government ministers, government officials, representatives of the international bodies that help manage these waters and representatives from the Chagossian community.

The story we hear from the local fishermen and NGOs is a familiar one.

All around the world local fishermen’s livelihoods, and the prosperity of their families and communities, are being threatened by industrial overfishing. It’s no different in Mauritius, where the destructive and sometimes illegal fishing practices both of the FAD-obsessed purse seine fleets and the longline fleets are depleting these waters.

Local fishermen complain of hardly seeing skipjack tuna anymore, normally an amazingly abundant fish. They worry that their children will not be able to make a living from the sea if nothing changes.

To address these issues we've had progressive talks with industry and government to explore what’s required to develop sustainable tuna fisheries that can support the international tuna industry and local fishermen.

This is just the start of our conversation for Mauritius to secure long-term jobs and protect the oceans and tuna stocks for future generations of all fishermen.

Scratching further beneath the surface we found that Mauritius is home to both extremes of the sustainability spectrum.

Princes, the major UK tuna brand that has a cannery on Mauritius, has committed to dump FADs with purse seine nets, the marine minefields that attract massive volumes of bycatch – switching instead to pole & line and FAD-free purse seine fishing.

Thon des Mascareignes owns the other cannery on the island, but that company takes its fish from the French and Spanish purse seine fleets operating in the Indian Ocean. These fleets are FAD-addicts, destroying juvenile tuna, sharks, rays and even turtles.

Thon des Mascareignes has a lot of ground to make up on its island competitors and our dialogue with the company has now started. As a marine Lorax might have said, ‘we speak for the oceans’.

Mauritius has the opportunity to look beyond the narrow, short-term model of simply licensing its waters to foreign fleets and allowing these vessels to be serviced in its port, a policy that generates some government and private income, but depletes local catches and encourages the destructive status quo of industrial fishing.

Instead it can take ownership of its waters, becoming a leader in developing a sustainable Indian Ocean fishing model that underpins long-term economic health for all players, big and small, ensures food security and protects marine resources.

Economic bottom lines are now bumping up against environmental limits. Change and leadership are both essential to bring us, and the tuna, back.

Simon Clydesdale is a Greenpeace UK oceans campaigner on the Rainbow Warrior