10/02/2016 5:09 AM AEDT | Updated 15/07/2016 12:51 PM AEST

Swimming Upstream In The Fight Against Overfishing

Challenging the tuna industry is the front-line of a global struggle for the future of our oceans. It's about taking back control of the ecosystems that give us life.

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'A daily catch of Tuna lined up ready for inspection and sale at an indoor Tuna market at Natchi-katsura, Japan.A simlar image:'

It was, famously, the fish that John West rejected that made John West the best -- or so went the ad campaign I knew as a kid. Back then, I think they were talking about the taste of their salmon rather than anything to with sustainability. But the tuna John West has rejected with the launch of their new policy last week is actually something good for the ocean.

Australia's biggest tuna brand -- they account for 40 percent of the local grocery market -- announced its complete transition to FAD-free tuna sourced from the Pacific.

FADs are fish aggregating devices -- they act like fish magnets, drawing in tuna and other marine life, making them easier to find and scoop up in giant 'purse seine' nets. But what makes them so efficient at catching tuna also results in an almost seven-fold increase in bycatch of juvenile tuna and other marine life such as sharks.

By rejecting FADs, John West has met the commitment they made to Greenpeace and our supporters way back in 2012. But the breakup wasn't easy for them. For a long time, the tuna industry told us our demands to stop using FADs amounted to an impossible ask. They've come a long way.

When we launched the Greenpeace consumer tuna guide in 2010, some companies couldn't tell us what ocean their tuna came from or even, scarily, what species it was. That meant they had no idea whether the tuna they were selling was overfished, or from waters where unacceptable practices like shark-finning were still permitted (it's banned in the Western Pacific now).

The biggest sustainability issue is overcapacity. It's a boring topic to talk about, and doesn't make for watchable YouTube videos, but it basically means too many boats chasing too few fish. As well as their wasteful bycatch rate, FADs multiply the overcapacity problem by making each boat more efficient. Global seafood mega corporations are addicted to FADs -- and to building more boats -- because the dwindling tuna are harder to find each year. Their business model is about a constant supply of cheap products -- whatever the cost to the oceans. And in spite of the warnings from scientists, that fishing is out of control.

In 2014, the industry caught a record 4.8 million tonnes of tuna, most of it skipjack for the canning industry, and most of that caught using FADs. This is an industry that needs an intervention.

So, three years and three months ago, I stood outside John West's headquarters in Melbourne as Greenpeace activists in shark suits occupied their roof, fake blood spurting from a giant fake tuna can. We'd been spoofing TV ads, putting up billboards, turning up at corporate events, and this was the finale. It wasn't subtle, but big and loud worked on this occasion, and we got the breakthrough agreement.

These wins are important for the example they set. Soon after John West committed to banning FADs in 2012, all the other Australian brands followed suit. But, at just under 50,000 tonnes a year, Australia is still a relatively small market by global standards.

This year, Greenpeace launched a global campaign targeting the biggest tuna company in the world, Thai Union (its flagship brand in the UK is coincidentally called John West, though there's no actual connection between the UK and Australian companies).

Thai Union is a behemoth, with the capacity to produce over 600,000 tonnes of tuna a year for the global market. Like the mainstream of the industry, Thai Union is wedded to destructive fishing practices, including FADs and unregulated longlining. Worse, across its seafood business it has been implicated time and again in serious cases of human rights and labour abuse.

Challenging the tuna industry is the front-line of a global struggle for the future of our oceans. It's about taking back control of the ecosystems that give us life. Healthy oceans are vital -- they help to regulate our climate and provide us with the air we breathe; they feed us and give livelihood to millions.

John West's decision to ban destructive practices is a big chapter in an even bigger story. For the sake of our oceans and the future of tuna sandwiches, let's hope John West Australia is a trendsetter rather than a lonely dancer.