When is a tuna not a tuna? Unfortunately too often in the Pacific where widely-used industrial tuna fishing methods catch far more species than just tuna.

Out on the water everything becomes tuna. That is until it’s been hauled on board tuna boats using large purse seine nets set around fish aggregation devices (FADs). However, by that time it’s usually too late and anything which is not tuna, collectively known as bycatch, is thrown back into the sea, often injured, dead or dying.

According to statistics circulated by Sealord, bycatch of other species is five to 10 times higher when purse seiners use FADs. This wasteful method also has serious impact on tuna stocks, as juvenile and undersized tunas make up 15-20 per cent of the catch.

New Zealand brands of canned tuna don’t catch their own tuna but instead buy it from fishing fleets – many of which are using this indiscriminate fishing method. That means it's up to canned tuna companies to adopt policies and ensure they aren't trading in unsustainably-caught tuna. But some companies are neglecting to do so.

To highlight this shameless waste of ocean life we’ve started an ad campaign calling on Sealord, New Zealand’s largest tuna brand, to change to more sustainably caught tuna.

Remember the fish species poster that used to be in every fish and chip shop? That’s the concept we’ve modeled our ad on except with one obvious difference. We feature 18 marine species, from sharks to tropical fish, but each and everyone is labelled as tuna. The tagline reads; Sealord tuna. What’s the catch?

We used this artwork for a poster, back in June, in central Wellington to coincide with World Oceans Day and the annual conference of the Seafood Industry. And now it’s appearing as a full page in New Idea magazine. No guessing where it might appear next.

It’s now been three months since we launched our campaign calling on New Zealand’s main brands of canned tuna to change to more sustainably caught tuna.

In response, Foodstuffs promptly announced it will be changing most of its Pams range of canned tuna to FAD-free by the end of the year.

They left Sealord, the other local company and New Zealand's biggest canned tuna brand, in their wake. Sealord continues to sell tuna caught using purse seine nets set around FADs. Already 13,000 emails have been sent to Sealord by concerned customers, urging the company to change their tuna.

Overseas John West has just committed to phase out its use of FAD-caught tuna, joining the rest of the UK's main canned tuna brands which have shifted, or committed to shift, to more sustainably caught tuna.

An updated ranking of the main tuna brands in Australia, released by Greenpeace today, shows two companies have committed to stop selling FAD-caught tuna and two others have improved on sustainability since last year.

Shame on you, Sealord – if all those companies can do the right thing by our oceans, so can you!