In September, the TV personality known as Sakana-kun was appointed to the position of guest assistant professor by the Tokyo University of Marine Science and Technology.

Famous for his childish demeanor and blowfish-shaped headgear, Sakana-kun certainly knows his fish, and his lack of a college degree doesn’t detract from his reliability as a marine expert. Having turned a childhood obsession with octopi into a lifelong study of sea life and all it entails, he first gained attention on the TV Tokyo contest show “TV Champion” when he beat out other piscine otaku with the depth and breadth of his knowledge: the contestants also had to have an understanding of fish cuisine, which is more important on TV than the zoology stuff.

Sakana-kun’s motto is “Take a look, take a bite (Mite miyo, tabete miyo),” which makes him the perfect fish expert for TV even beyond his big smile and ingratiating manner. His entertaining lectures on the habits and physiology of fish on variety and travel programs only add to viewers’ pleasure in consuming them. Sakana-kun’s thoroughness extends to his being an accomplished sushi preparer.

This dual expertise makes sense on TV but it places Sakana-kun in an awkward position with regards to the increasing global concern over dwindling fish stocks in the world’s oceans. Though he has written books for children on ecological matters, Sakana-kun has yet to weigh in publicly on the crisis. And whereas he’s the go-to guy for media quotes about anything related to fish, no one has asked him about the bombshell article published in the journal Science earlier this month that said the world’s commercial fish stocks will collapse by the year 2048 if consumption trends don’t change.

It may be too much to expect the preternaturally cheerful ichthyologist to comment on something so dire, but he certainly must have an opinion.

The Japanese media have given the Science article only cursory attention even though Japan consumes more seafood than any other large country in the world — according to the U.N. about 67 kg per capita per year. The next biggest consumer is Malaysia at about 59 kg.

Controlling fish harvests depends on monitoring, but monitoring fishing activities isn’t the same as counting heads of cattle. Once fish are caught, it is too late. The aim, then, is to prevent fishermen from catching too much, but since the oceans are vast and fish stocks move around, it is very difficult to keep track of who is catching what and where.

The effectiveness of catch quotas has yet to be proven, even when governments pledge to observe them.

In a series of Asahi Shimbun articles published earlier this month explaining new quotas that were recently approved by various international tuna conservation organizations, it became clear that Mediterranean tuna is now in danger of being wiped out because of overfishing whose purpose is to provide Japan with toro, the fatty tuna flesh so valued by sushi aficionados. Much of this tuna comes from the Mediterranean, and most of it was farm-raised.

European fishermen catch young tuna and place them in enclosures in the ocean, where they fatten the tuna by feeding them other fish. When they are big enough they are sold at high prices. Australia also practices this kind of tuna cultivation, and the bulk of the product goes to the Japanese market.

Starting next year, Japan’s own catch quota for southern bluefin tuna will be cut in half. The Asahi says that the international Commission for the Conservation of Southern Bluefin Tuna is “punishing” Japan because it “suspects” it is catching too much tuna.

As it happens, even Japan’s own Fishery Agency suspects overfishing on the part of domestic producers, saying that in 2005 the Japanese catch for southern bluefin “appears to have exceeded” the quota by 1,800 tons. But what can they do about it? Once they discover the excess the fish have already entered the market.

The same goes for tuna from other regions, including the Mediterranean. The International Commission for the Conservation of Atlantic Tunas has told Japan not to buy fish from countries and regions that violate quotas. In 2005, Japan imported 27,000 tons of tuna from the Mediterranean, 93 percent of which was raised. Are cultivated fish subject to the quota since they aren’t, strictly speaking, caught? The ICCAT estimates that Mediterranean fishermen caught anywhere from 44,000 to 60,000 tons of tuna in 2005, amounts that greatly exceed the region’s 32,000-ton quota. Most of this tuna eventually makes its way to Japan.

Quotas are based on country of origin and where fish are caught, but fishing boats can easily lie about where their catch came from and even about their country of registry. The only way to prevent overfishing is at the source, before the fish are dumped into the hold, and the only way to do that is to have an observer on every fishing boat in the world with the authority to tell fishermen to stop fishing.

But the only real solution to the tuna crisis is to decrease demand. Japan consumes 40 percent of the world’s bluefin tuna catch and about a fourth (530,000 tons) of all species of tuna that are caught everywhere. Once upon a time, tuna sushi was limited to the well-to-do, but now it’s affordable to everyone at supermarkets and chain restaurants thanks mainly to cultivation methods like those used in the Atlantic and Australia.

The media is complicit in the tuna crisis because ubiquitous food shows constantly give viewers the impression that everybody can enjoy as much toro and maguro as they can stuff into their faces.

Producers who make such shows are not expected to bring up depressing things like collapsing fisheries, but Sa-kana-kun, who loves fish and not just because they’re delicious, might be expected to defend the future of his finny friends. After all, it’s his future, too.