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Stalking—and Saving—the Wild Eel: An Interview with Marine Biologist Tsukamoto Katsumi

Tsukamoto Katsumi has devoted most of his long career to the study of the Japanese eel and its spawning behavior. Now, with overfishing and other pressures threatening populations of freshwater eel worldwide, Tsukamoto has joined forces with colleagues from China, South Korea, and Taiwan in a race to unlock the secrets of these mysterious—and famously tasty—migratory fish and rescue them from extinction.

Tsukamoto Katsumi

Tsukamoto KatsumiProfessor of marine biology, College of Bioresource Sciences, Nihon University. Professor emeritus, University of Tokyo. Has spent more than 40 years studying the migratory and reproductive behavior of the Japanese eel (Anguilla japonica), known to lovers of Japanese cuisine as unagi. After locating the eels’ spawning area in 1991, his team continued its research expeditions and in 2009 made history by collecting Japanese eel eggs from the wild and identifying a specific spawning site. Tsukamoto continues his studies in the field and the laboratory with the aim of unlocking the secrets of the eels’ reproductive behavior and supporting sustainable resource management.

INTERVIEWER In November last year, you founded the East Asia Eel Society with the participation of experts from China, South Korea, and Taiwan, as well as Japan. How did that come about? What are the organization’s aims, and how does it plan to achieve them?

TSUKAMOTO KATSUMI The East Asia Eel Resource Consortium, which was the forerunner of the East Asia Eel Society, has been active for almost twenty years, ever since 1998. But it was more in the nature of a private group organized and run by my research team. We decided we needed a full-fledged international society open to a wide range of participants to facilitate the exchange of scientific information on the eel. We started out with about a hundred members—primarily scientists, but also people in the fishing and seafood industries, amateur eel enthusiasts, and so forth. Having an academic platform makes it easier to share information that can provide a scientific basis for resource management and conservation policies. That was another benefit we had in mind.

One of our goals is to establish “eel science” as an academic field in its own right. We also want to educate the public about it. The issues surrounding resource management are closely tied up with the way we function as a society. If we want to keep unagi as part of our diet, we need to study the issue from a cultural angle as well as a scientific standpoint. I’d like to see eel science develop into a multidisciplinary field that integrates natural science, social science, and the humanities.

Inching Toward Conservation

INTERVIEWER The Japanese eel is officially an endangered species. Still, we hear that unagi is increasingly popular among diners in Taiwan and China. Glass eels [transparent juveniles] continue to be harvested in great numbers from estuaries around East Asia, raised to maturity on eel farms, and consumed. To what degree are people around the region conscious of the need to protect the species?

TSUKAMOTO Japan is the most acutely aware of the problem. That’s why our Fisheries Agency has taken the lead in the four-way talks [with China, South Korea, and Taiwan] on eel conservation and resource management launched in 2012. The Taiwanese also have a fairly high level of awareness. The Chinese, not so much. South Korea probably falls about midway between Taiwan and China.

Larvae (leptocephali) of Japanese eel. (Photo courtesy of Tsukamoto Katsumi.)

Glass eels (transparent juveniles), also known as elvers. (Photo courtesy of Tsukamoto Katsumi.)

Japanese researchers have been working to develop full-cycle eel aquaculture ever since the 1960s. Even then, people in fisheries management and industry were concerned about stock levels. That’s because the number of glass eels arriving on our shores fluctuates widely from year to year. But the average number of landings used to be much higher. Since the 1970s, there’s been a sharp downward trend, and now their numbers fluctuate at a much lower level. Unfortunately, no one has been able to develop a commercially viable method of breeding eels in captivity. In the wild, they spawn far out in the open sea, so no one yet has been able to pin down the exact conditions for reproduction. All the farm-raised unagi we eat today is grown from wild-caught glass eels.

A Call for Restraint

INTERVIEWER In 2013, when the glass eel catch fell to just five tons, there was a widespread feeling of panic in Japan. People were afraid that unagi was going to disappear from the menu forever. In 2014, the International Union for Conservation of Nature designated the Japanese eel an endangered species, and after that, the Japanese government took a few steps to protect stocks, such as requiring eel farmers to be licensed and imposing limits on glass-eel procurement. So, where do things stand now, three or four years later?

TSUKAMOTO I would say consumers are getting used to thinking of unagi as a scarce and expensive item. Around 2000, the Japanese were consuming more than 100,000 tons of eel annually, much of it imported from China. In the prepared-food section of Japanese department stores, the counters were laden with grilled unagi at throwaway prices. Then international trade in European eels was banned, imports from China [where European eels were being farmed] plummeted, and prices went up.(*1)

Over the past four years, scientists like myself have been warning that we’re in danger of depleting our stocks of Japanese eel if we don’t consume them more sparingly, and I think consumers are beginning to get the message.

To conserve and replenish our eel fisheries, the main thing we need to do is protect the adult eels and make sure that as many as possible return to the ocean to spawn. These eels are an international resource; all four East Asian countries have to work together to protect it. As a major producer, China is a big piece of the puzzle. I’m hopeful the Chinese will do their part to save the eels by addressing environmental issues in their waterways and limiting catches of glass eels. I’d like to see catches dialed back to where they were forty or fifty years ago.

INTERVIEWER What’s your advice to Japanese consumers who love their unagi?

TSUKAMOTO The Japanese really should cut back a bit on their consumption of eel. But this is also an admonition to retailers, who continue to do everything possible to encourage mass consumption. Granted, there are a few responsible ones out there who are saying, Yes, unagi is a shining example of Japanese food culture, but we need to consume responsibly if we want to preserve it for generations to come. But the vast majority of retailers take the attitude that, if it’s profitable, then of course they’re going to sell as much as they can.

In terms of consumer behavior, we advocate limiting one’s consumption of unagi to a few special days out of the year. I would like consumers to understand the situation facing the Japanese eel and treat unagi as a somewhat extravagant indulgence for special occasions.

(*1) ^ Annual consumption is now around 50,000 tons. —Ed.

  • [2017.07.25]
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