Tuna ranch hormone cocktail could save bluefin

They’re about four months old, a foot long, and might represent the salvation — albeit an uncertain, ambiguous salvation — of that magnificent, desperately threatened creature.

 

The fish belong to Clean Seas Tuna, an Australian company that for the last decade has pursued the elusive task of spawning bluefin in captivity. Researchers from Japan and Europe are but a few steps behind them. Though far from complete, their work has made bluefin aquaculture, once nearly unthinkable, a possibility.

 

 “There’s still a lot of work to be done. I don’t want to give the impression that it’s complete. But if this species can be aquacultured, it will take pressure off from fishing,” said Abigail Elizur, an aquaculture biotechnologist at Australia’s University of the Sunshine Coast.

 

News of breeding success comes with the three bluefin species — Northern, Southern and Pacific — speeding towards extinction, the victim of something close to a marine version of the 19th century buffalo slaughter. In the last 30 years, bluefin populations around the world have collapsed. Fishing fleets with spotter planes have chased ever-smaller, ever-younger fish, catching them at sea and hauling them to shoreline pens to be fattened and killed before they’re even old enough to reproduce.

 

That’s left the seas nearly barren of breeding-age bluefin. In April, the World Wildlife Federation declared that current overfishing rates would cause an irreversible collapse of Northern bluefin within three years. The Southern is considered critically endangered, and it’s thought that any increase in fishing pressure will put the Pacific on a track to oblivion.

 

Despite alarm among scientists, however, overfishing has continued. Two years ago, researchers from the International Commission for the Conservation of Atlantic Tunas, or ICCAT — the regulators of Northern bluefin fishing — recommended a global quota of 15,000 tons. ICCAT officials ignored them, setting the limit at twice that number. They’ve since dropped it to 22,500 tons, but their scientists now say just 7,500 tons is sustainable. The fishing industry has ignored all those numbers, hauling in some 60,000 tons of Northern bluefin yearly. An independent review panel called ICCAT an “international disgrace,” a phrase that could just as easily apply to the management of Southern and Pacific stocks.

 

Ending the disgrace, however, is far easier said than done. Prized for their tender, fat-laced meat, bluefin tuna are a $7.2 billion global industry. In January, a 440-pound bluefin sold for $173,000 at a Tokyo market. It was the highest price ever paid for a single fish, and an object lesson in how, in the absence of sane regulation, impending extinction increases incentives for further exploitation. (It’s not for nothing that the Italian mafia is now linked to the bluefin trade; one conservation-minded ICCAT official famously found a white lily at her seat before a 2006 meeting.) Companies from Japan, which consumes three-quarters of all bluefin and effectively controls the global trade, have put an estimated 30,000 tons of the fish, worth between $10 billion and $20 billion, in frozen storage. Overfishing will only raise their price.

 

Compared with such profits, objections by conservationists, or even pledged bluefin boycotts by France and Spain and the United Kingdom, are relatively meaningless. The most realistic possibility for bluefin survival may be fish farms: If they can be raised in captivity, at-sea fishing should become less important, and wild bluefin might finally be protected.

 

But people have long known more about cooking bluefin than keeping them alive. The fish roam for thousands of miles at sea, die if they stop swimming, and have proven unsuitable for the sort of farms used in salmon aquaculture. Even when researchers figured out how to design pens in which the bluefin wouldn’t thrash themselves to death, they still refused to spawn. That might finally be changing.

 

“It’s now a technology question, not a biology question,” said fish physiologist Christopher Bridges of Heinrich Heine University in Dusseldorf. “How long will this take in terms of development and experimentation? That’s the bottleneck. And I have no doubt this bottleneck will be solved.”

 

Bridges is one of dozens of European scientists involved with the Allotuna and the Selfdott Northern bluefin-breeding programs. They’ve developed hormone treatments that coax tuna into spawning while they’re held in coastal pens. That seemingly simple feat hadn’t yet been done in the Northern bluefin, whose reproductive habits are in many ways still a mystery.

 

“Everyone in the tuna community was celebrating with them and for them,” said Alizur.

 

In late June, the researchers collected nearly 200 million eggs, or the output of about 20 females. The eggs were sent to hatcheries around the Mediterranean, where biologists will commence raising them from egg to larva to fingerling. That tricky progression is considered a benchmark in tuna aquaculture.

 

Having adjusted the Northern bluefin hormone treatments to fit their Pacific stock, they keep their fish in an onshore aquarium where water temperature, lighting and current are controlled. About 50 million eggs were fertilized in this artificial tuna love nest in March, ultimately producing the 60 foot-long fish now swimming in the company’s Port Lincoln aquarium.

 

The numbers seem humble, but the ability to conduct the spawning in a completely controlled environment heralds “the start of a commercial operation,” said Alizur. Clean Seas intends to have 250,000 bluefin at their hatchery by 2015.

 

For all their successes, however, that timetable may be optimistic. Researchers in Japan have tried to breed Southern bluefin in captivity for more than 30 years, but though they’ve learned to keep the fish alive, year-to-year egg harvests have been inconsistent. The European and Australian teams seem to have solved that problem, but there’s still more to do.

 

“We still need to optimize the conditions of larval rearing, what to feed them, the best conditions, what they need for space and special food,” said Alizur. “We all get excited, and rightfully so, but this is only the first step. It’s a bit like giving birth. It’s a huge thing, but once the baby is born, you focus on the feeding and growing, and end up having a short memory about the birth itself. We’re at that stage.”

 

Other dynamics may yet affect the nascent industry. Some researchers suspect that Japanese bluefin aquaculture has been constrained by pressure from the nation’s fishing industry, much like American automobile companies squashed innovation.

 

Even if farmed bluefin flourish, feeding them could be a problem. Though the Japanese researchers are trying to develop a grain-based diet, it’s possible — perhaps probable — that bluefin will insist on natural fare. “Presumably that will require vast amounts of bait fish to feed them,” said Richard Ellis, author of Tuna: A Love Story. “From the perspective of catching fish to feed fish, this is a step backwards.”

 

Unless drastic conservation measures are taken soon, bluefin aquaculture won’t mature in time to reduce fishing pressure, said Ellis. In the interim, companies — including Clean Seas — will still catch bluefin at sea.

 

Aquaculture, “together with quota cuts, is the way forward,” said Bridges.

 

For Ellis, who refuses to eat bluefin, the ideal solution is to “not treat this great creature solely as a food item,” he said. “But I don’t have any hope that people will stop eating it.”