When you look at fish imported from Fiji, you have to look at the New Zealand company Solander. It was one of the businesses Stuff Circuit approached in our survey of importers, and it was the first to respond.

Company owner Charles Hufflett rang almost straight away to explain Solander’s supply chain.

He describes tuna as the Nelson-based company’s signature line. Some is caught in New Zealand, but most is sales of yellowfin and bigeye caught in Fiji, processed into wholesale fillet sizes and flown to Auckland. Clients include top restaurants and resorts, looking to serve fresh, premium tuna.

Solander owns a subsidiary which operates about 10 vessels and a processing facility in Fiji. The boats are longliners, but they operate within Fiji waters, and are mostly crewed by locals. “It means we’re operating under Fiji laws, including labour laws,” says Hufflett.

This oversight, plus what he sees when he visits regularly, gives him confidence about the conditions for the people who work Solander boats.

That’s the case with most boats fishing in local waters - they’re not the deep-water vessels plying the high seas for months on end that concern campaigners and investigators.

Most of the other boats based in Fiji are Chinese-linked, though Fiji laws require businesses to be majority locally-owned. The move into the fishing industry has been part of China’s expansion in the Pacific over the past 20 years or so, says Hufflett.

Taiwan, too, has a considerable presence in Fiji.

A majority of the processing factories are linked to China and Taiwan. And it’s through these processing facilities that Fiji has a connection to the deep water fleet.

A giant Taiwanese company, FCF, is the buyer for the Fiji government cannery in Levuka. Hufflett says many Taiwanese and Chinese off-shore vessels off-load in Levuka. “They’re not Fiji-flagged, they are foreign vessels landing into that port.”

The fish off-loaded there is mostly albacore, most of it frozen.

Remember most of the fish that comes to New Zealand from Fiji is fresh or chilled (though there is that 450,000 kg of frozen, ground tuna meat imported since 2007).

Hufflett isn’t happy about imports of frozen tuna, partly because of the way some of it is treated, allowing it to keep its colour and be preserved for longer.

“I think it’s tasteless but they’re our competitors so I would say that.”

But the other issue with frozen tuna, of course, is it’s harder to know where it comes from.

Which is the point campaigners are concerned about - if we don’t know where it comes from, how do we know what the conditions were like onboard the boat that caught it?

So, we’ve established that Taiwan has connections to Fiji, the biggest source of tuna for New Zealand. But with most tuna from Fiji fresh or chilled yellowfin, unlikely to have come from the Taiwanese fleet or other deep water vessels, establishing evidence of slave-tainted tuna coming via Fiji is difficult, although there are still questions about that frozen, ground albacore.

Are there any direct Taiwanese connections to New Zealand? Companies Office records show that in 2008, a British Virgin Islands-registered subsidiary of Taiwanese giant FCF became a majority owner of a New Zealand company, Temuka Seafoods. The BVI company, Skymax International, owns 80 per cent of Temuka, which has two Taiwanese directors.

One has connections to FCF.

Temuka’s registered address is in Christchurch, but the MPI register of importers shows another address, in south Auckland, in a quiet industrial area. Refrigerated trucks go up and down the long driveway.

It certainly doesn’t look like the New Zealand landing base for one of the biggest tuna companies in the world.

The property is also the home of a fish importing business called Pendarves, which brings fresh and chilled tuna from Fiji.

A director of Pendarves, Ben Burney, is also a director of Temuka.

So what, if any, connection does FCF have with fish imports to New Zealand?

Burney, a businessman well-known and well-liked in the New Zealand tuna industry, is happy to speak to Stuff Circuit, keen to explain the division between the Taiwanese majority-owned company, Temuka, and Pendarves, which supplies tuna to supermarket chain Foodstuffs and fish wholesalers.

Burney is very firm, saying there is no connection. Pendarves is the company which imports tuna for consumption in New Zealand; Temuka is an international bait business.

Through Temuka, Burney says, he buys fish globally and sells it to boats around the world. The Taiwanese, he says, are simply investors.

Later, he rings back to emphasise the difference between the businesses, telling us he only deals with Fiji-based companies to buy the tuna for the New Zealand market - he even invites us to go to Fiji to have a look for ourselves.

Everything he buys is ethically sourced, he says, with workers protected by Fiji labour laws.

But what about through the bait business? Is he sure he’s not inadvertently supporting boats which don’t give their crew a fair deal? “Definitely.”

Burney says that New Zealand has a reputation to protect internationally.

Nevertheless, could slave-tainted fish be ending up on New Zealand plates? “Definitely not.

“In all the time that I’ve been doing this business I’ve never had fish like that offered to me.”

So, a New Zealander in the business, with connections to Taiwan, is adamant no slave-tainted fish are ending up in New Zealand.

And an independent fisheries expert with knowledge of the Pacific fisheries, Francisco Blaha, says that in the case of fish caught in the waters of island nations, he agrees.

“Most of the tuna [coming to New Zealand] will have come from Fiji or Tonga from vessels that are being operated by local crews and that are fishing under legal conditions.”

But things get tricky when you are dealing with frozen tuna with a murky supply chain.

Which makes Tim McKinnel adamant that slave-tainted fish is likely to be landing in New Zealand. “Oh I think it's a very genuine risk but it's so difficult to unwind supply chains and it's difficult to know for sure who's at risk and that damages the whole industry. And as you rightly pointed out there are some ethical, sustainable operators out there. We need to know who they are and we need to be able to find out who the baddies are.”

Glenn Simmons agrees: “I'd say it's close to a 100 percent chance. In some cases it's almost certain that we have eaten fish caught by crew under conditions of forced labour.”

The industry body representing the New Zealand industry, Seafood NZ, says consumers should be wary of fish coming into the country.

“All vessels and crew fishing in New Zealand must abide by New Zealand’s stringent labour laws. Other countries will have different labour requirements, and while this is outside our jurisdiction the consumer should be mindful.”

In Taiwan, the Fisheries Agency, which has responsibility for oversight of the tuna industry, says it is leading changes.

The agency insists it is “dedicated to enhancing the protection of rights and benefits of foreign crew members”.

While admitting that, historically, legal protections for those crews was inadequate, the agency says the passing of new legislation in 2017 has improved the situation.

The law required minimum wages, daily rest time of 10 hours with four days off per month, and insurance to cover costs in the event of death and injury.

“Meanwhile, starting from 2017, personnel have been assigned to interview foreign crew members in domestic and foreign ports using questionnaires,” says the agency. “In the event that any operator or employment agent is suspicious of violation, [an] investigation will be carried out accordingly.”

It also says it wants to invite NGOs for discussions to help improve regulations.

At Greenpeace’s Taiwan headquarters, Jodie Yi Chiao Lee remains sceptical. “I think human rights issues have been in the tuna industry for a long while, decades...it’s systemic,” she says. The industry and the regulators are entwined.

She has more faith in the power of consumers to sort out the issues. “Consumers should be aware of where your fish comes - make sure the fish on your dinner table is not coming from [sources where there are] human rights abuses. There should be labels showing where the fish is from, where it’s being processed - and that is possible.”

Simmons agrees that consumers are the key.

“What it needs is increased transparency, it needs sunlight,” says Simmons. “You know sunlight has a way of curing a lot of problems. And that would go a long way to curing the problems that are rampant in the fishing industry.”

It’s too late for Supriyanto. And nothing can ever bring back the skipper of the Tunago Number 61, nor free the men who killed him. But as consumers are we prepared to stand by and allow the carnage on the high seas to continue?