Taiwan Today

The crowd at the Bluefin Tuna Cultural Festival in Tungkang (also spelled Donggang), Pingtung County, southern Taiwan always cheers when the season’s first bluefin tuna is auctioned off to kick-start the event, which usually occurs in May and June each year. The fish typically weighs around 200 kilograms and can sell for as much as NT$1.7 million (US$56,700), as bluefin flesh makes for a pricey delicacy when cut into thin slices for sashimi or sushi.

But the situation is not as rosy as the Pingtung festival would make it seem, as demand—mostly from Japan—for the ever-popular, deliciously creamy taste of bluefin tuna has held steady even as the fish has become harder to find. The July 2013 plenary session of the International Scientific Committee (ISC) for Tuna and Tuna-like Species in the North Pacific Ocean, for example, stated that “bluefin tuna are overfished and experiencing overfishing.” Meanwhile, the Commission for the Conservation and Management of Highly Migratory Fish Stocks in the Western and Central Pacific Ocean, of which Taiwan is a member, agreed in September 2013 that this year’s catch of juvenile bluefin tuna in the Pacific should be at least 15 percent below the 2002–2004 average.

Bluefin are far from the only kind of tuna to face such pressure, as another recent ISC report found that decades of overfishing had led to a colossal 96.4 percent decline in all tuna species worldwide. That undersea crisis has inevitably impacted Taiwan’s fishing industry, which started focusing on tuna in the 1970s and saw annual total tuna catches peak in the late 1990s. Once the world’s sixth-largest provider of tuna and a dominant exporter to Japan, Taiwan has seen its catches decrease rapidly in recent years due to depleted tuna stocks and the imposition of quotas by various international deep-sea fisheries management commissions. The latest statistics of the Fisheries Agency under the Republic of China Council of Agriculture (COA) show that in 2012, the nation’s tuna catch had declined from the level recorded a decade earlier to reach 358,000 metric tons, a 16 percent decrease. The 2012 catch had a total market value of NT$35.2 billion (US$1.19 billion) and comprised tuna varieties including skipjack (50.8 percent), bigeye (18 percent), yellowfin (17 percent), longfin albacore (13.6 percent) and bluefin (0.2 percent).

In Tungkang, the catch of premium bluefin tuna, which is sometimes referred to by scientists as the tiger of the sea due to its highly predatory behavior, plummeted from 1,349 metric tons valued at NT$534 million (US$15.8 million) in 2001 to 190 metric tons valued at NT$167 million (US$5.6 million) in 2013, data from the Tungkang Fishermen’s Association shows.

The sharp decline in the local catch provides further evidence of the worldwide decline in tuna stocks. One factor behind that drop is the continued use of deep water purse seining, in which a large net is towed into place around a school of fish, then closed and hoisted aboard. Environmentalists have long opposed purse seining because it leads to the bycatch of non-target species, but the technique continues to be used by the fishing vessels of many nations, including Taiwan. “Major fishing countries still allow the operation of purse seine fishing vessels, which invariably catch and endanger juvenile bluefin tuna,” says Lin Han-chou (林漢丑), executive secretary of the association. The shrinking catch and persistent demand have driven prices higher, Lin adds.

To conserve wild bluefin stocks, Japan, which is the world’s largest tuna consumer as well as supplier, has artificially bred and farmed the fish for four decades. Taiwan lies well south of Japan, however, and the temperature of the seawater around Taiwan has proven too warm to farm the species.

Instead, Taiwan is attempting to breed and rear yellowfin tuna, which is an abundant species in local waters, according to Wu Long-jing (吳龍靜), chief of the Coastal and Offshore Resources Research Center under the COA’s Fisheries Research Institute. “Our ultimate goal is to facilitate self-sustained aquaculture and domestication of yellowfin tuna,” Wu says.

Wu’s center began its initial assessment of yellowfin tuna populations in 1997 by installing 42 fish aggregation devices, or artificial structures deployed to attract fish, in waters frequented by the species. In 2004, the center collaborated with Pingtung County to launch a yellowfin aquaculture scheme that was one of the first initiatives of its kind in Asia. That effort involved catching wild young yellowfin weighing less than 1 kilogram and raising them in a net cage measuring 16 meters in diameter in the waters near Xiaoliuqiu, an island off the west coast of Pingtung County.

So far, the survival rate for the yellowfin raised in the net cage has remained low, Wu says. Tuna move effortlessly in the water and even continue gliding forward while sleeping to keep oxygenated water flowing through their gills. Some tuna species are capable of swimming as fast as 80 kilometers per hour. Such speed, however, can be a problem in small net cages, where collisions between fast-moving fish can result in death. It is also challenging for the researchers to separate and move farmed yellowfin, as the fish are quite delicate and contact with a researcher’s hand can cause bruising.

In addition, yellowfin tuna are very sensitive to environmental conditions, as murky water can clog their gills and too much light can blind them. “Our biggest challenges come from extreme weather or typhoons, which often lead to rapid fluctuations in the coastal seawater’s temperature and pH value. Changes to those factors are detrimental to the health of the fish in the cage,” Wu says.

To counter such environmental problems, Wu says the center is studying the possibility of relocating the net cage further offshore, where it could be sunk in deeper waters. That would be especially helpful in typhoon season, as a deeper cage would protect the fish from stormy surface conditions and polluted runoff. Moving the cage, however, would make management more costly, difficult and time consuming, and those issues need to be addressed first, he adds.

In spite of such trials, the center’s cage-raised, 1-year-old yellowfin have grown to weigh as much as 10 kilograms, the project’s latest milestone. Wu acknowledges that there is still a long way to go, however, as wild yellowfin tuna can weigh up to 70 kilograms at 3 to 5 years of age.

Wu explains that tuna are voracious eaters with a very fast metabolism. Japanese bluefin breeders, for example, have reported captive tuna gaining only 1 kilogram in weight after being fed an average of 20 kilograms of smaller fish, he says.

Such a ravenous appetite means aquaculture operations that catch wild fish to feed farmed tuna can have a serious impact on local ecosystems. Wu’s center, however, takes a unique, eco-friendly approach by feeding its yellowfin mostly juvenile farmed milkfish, a silvery, bony food fish. Milkfish used as feed average about 10 centimeters in length, although they can grow to as long as 1 meter in the wild. Milkfish have been farmed in Taiwan for hundreds of years, and local land-based fish farms have developed the ability to produce milkfish larvae, so they do not have to take milkfish fry from the sea. Thus, the center’s approach to feeding yellowfin helps minimize the exploitation of marine resources, Wu says.

The center takes the unusual step of raising its milkfish on rice bran, prompting Wu to joke that “Our milkfish are vegetarian, so to speak.” Feeding the milkfish rice bran also conserves resources, as the bran is a byproduct of the rice milling process.

Premium Flavor

Market demand is generally greater for tuna with a higher percentage of fat, which enhances the flavor of the meat. The fat composition in the back and abdomen of the center’s farm-raised yellowfin is five to 10 times that of wild tuna. The fat is also distributed in other parts of the fish, giving the flesh a bright pink color and a texture comparable to that of premium bluefin tuna, which should help farmed yellowfin capture a share of the market, Wu says.

In terms of cost feasibility, the center is now able to raise tuna at an average cost of NT$30 (US$1) per kilogram, higher than the market price of NT$20 (US$0.66) per kilogram for wild tuna. Wu is confident that the cost of farmed tuna can be reduced by achieving an economy of scale.

Those who make a living catching wild tuna are less sanguine about the farmed variety. “Farm-raised tuna may be able to provide an alternative supply, but it’s unlikely to replace wild tuna,” says Edward Huang (黃昭欽), secretary-general of the Taiwan Tuna Association.

Lin of the Tungkang Fishermen’s Association also expresses doubt, saying that farmed tuna does not taste as good as wild tuna. That view, however, is not shared by Japanese cuisine restaurant owner and chef David Huang (黃重賢), who says that farmed fish can taste as good as wild fish, as the flavor is largely determined by the feed and whether the cage is big enough to allow them to swim at their normal speed.

That is not to say that all consumers would be ready to embrace farmed yellowfin. “Foodies are concerned about whether the flesh contains chemicals or even artificial hormones,” David Huang says.

Traditional fishermen are also fearful of the impact farmed yellowfin could have on the market. “We don’t look forward to seeing artificially bred tuna, which we believe will drive prices down,” Lin says. Pingtung County Magistrate Tsao Chih-hung (曹啟鴻), however, does not believe that raising yellowfin in captivity would depress prices if output were controlled sufficiently to avoid market saturation. Providing that production and pricing were stabilized, yellowfin aquaculture operations would boost the local economy, Tsao says. “The financial benefits could even extend to an industrial cluster that includes tuna fishermen, feed suppliers and net-cage manufacturers,” he adds.

The magistrate says his office plans to study tuna farming in Australia, which began raising captive southern bluefin tuna in the early 1990s. One objective of the study will be evaluating that country’s experience to develop the most appropriate business model for Taiwan. After accomplishing that step, the local government will seek private investors, as setting up a tuna farm requires considerable capital. One such investor, Hung Kuo-ching (洪國清), a doctor from Xiaoliuqiu who operates a family-owned cobia (aka black kingfish) farm there, supports the center’s tuna-rearing project. Between 2004 and 2011, Hung conducted his own yellowfin farming experiment by keeping the tuna in net cages suspended at sea. He invested millions of dollars in that effort, only to see it fail in the end. He has no regrets, however, as the endeavor showed him that wild tuna can be domesticated and their survival rate can be increased. In Hung’s view, the biggest benefit of farming tuna is its potential to reduce pressure on wild stocks. “Today’s tuna fishing activities may not be sustainable tomorrow,” he says. “We can’t keep on exploiting the ocean’s resources.”

With an eye toward achieving such sustainability, Wu says the COA has set the goal of developing all the technologies needed to breed and rear captive yellowfin. “That means we have to succeed in spawning the species artificially,” he says. “In the near future, we hope to gain the capacity to release our farmed yellowfin tuna back into the sea should the species’ population be threatened.”

Along with Wu’s Coastal and Offshore Resources Research Center, other units operating under the COA’s Fisheries Research Institute are involved in the effort to spawn yellowfin. For example, Lee Yen-horn (李彥宏), a lead researcher at the Tungkang Biotechnology Research Center, says his laboratory’s captive yellowfin have spawned twice, with the first success occurring in June 2012 and the second in March 2013.

However, none of the yellowfin larvae born of those efforts survived for more than 12 days, and the center’s researchers have not yet determined the cause of death. Shukei Masuma, a yellowfin tuna expert from Kinki University in Wakayama Prefecture, Japan says that plausible causes include improper water temperature, poor egg quality, nutritional factors such as feed lacking in appropriate rotifer content and “insufficient feeding under high temperature [that does not match] the basic metabolism of yellowfin larvae.”

As the factor responsible for the 100-percent mortality rate has yet to be identified, Lee says that the Tungkang center is moving forward by targeting several possible causes at once. “The pressure is on because we’ve been told we need to achieve spawning success by the end of 2019,” he says. The center is therefore working hard to develop healthier, more nutrient-rich feed as well as technologies that will maintain water salinity at less than 3.4 percent and the temperature at between 28 and 30 degrees Celsius.

Clearer and Cooler

Meanwhile, the Fisheries Research Institute’s Eastern Marine Biology Research Center in Taitung County, eastern Taiwan has been developing aquaculture applications for deep sea water that is pumped from an area located 5 kilometers offshore and 600 meters below the surface. Researchers believe that filling the pond with clearer and cooler deep sea water will be conducive for reproduction. In November 2012, the Taitung center began nurturing 30 yellowfin tuna and five bigeye tuna in a dedicated pond. While that effort experienced a setback when the center’s pumping facility was obstructed by debris stirred up by Typhoon Usagi in September 2013, the tuna will not reach sexual maturity for another year or two, which should allow enough time for the restoration of the station’s pumping capability.

The presence of the bigeye tuna in the Taitung center’s pond indicates that the COA has more in mind than just spawning yellowfin. “Another long-term goal of ours is to leverage our technology to breed other tuna species with greater commercial value such as bigeye tuna,” Wu says. “Sixty percent of our technology is relevant for farm-raising bigeye.”

Masuma, for one, is optimistic about the outcome of the COA’s effort to produce viable yellowfin larvae. “Taiwan has a high-level technique for rearing marine fish larvae. I think they’ll overcome some problems for early-stage [spawning] yellowfin tuna,” he says. The government’s three research centers continue to pursue that goal vigorously. If their efforts pay off, Taiwan will become the only other country in Asia besides Japan with the capacity to farm tuna, which promises major benefits not only for the aquaculture industry, but also for the marine environment.

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Joyce Huang is a contributing writer based in Taipei.

Copyright © 2014 by Joyce Huang