Mackerel, Tuna and Other Slowly Unfolding Problems

By Jared Diamond / Special to The Yomiuri Shimbun

11:00 JST, September 19, 2025

I grew up in the American seaport city of Boston on the U.S. Atlantic coast, where I was born in 1937. The fish that was most available then in Boston fish stores, and that my mother most often cooked for us, was Atlantic mackerel. I loved it! It’s an oily fish with lots of brown fat, and with a strong taste — much more interesting than tasteless boring white fish like cod and haddock.

My fondness for mackerel was shared by thousands of Bostonians. It was so abundant in the ocean nearby that it was caught in huge quantities, shipped in big barrels and was a major contributor to the local economy throughout much of Boston’s history.

In 1966 I moved across the U.S. to Los Angeles on the Pacific coast, where different species of seafood were available. I didn’t ask myself why Atlantic mackerel weren’t being shipped to Los Angeles. Not until 2002 did my wife and I begin returning to the Boston area every year for our summer vacation. I was eagerly looking forward to reconnecting with the beloved oily mackerel of my childhood. But whenever I ask for mackerel now in Boston fish stores, I’m told that they don’t have any, and that fishermen rarely catch them.

What had happened to those superabundant mackerel? Alas, they were overfished, year after year, until the mackerel fishery collapsed, never recovered, and other boring fish species took over. The decline was slow and irregular. Catches fluctuated up and down. A low year was likely to be followed by a better year. Fishermen and mackerel-lovers didn’t notice that the long-term trend was downwards — unless they moved away from Boston for 36 years, then came back as I did, and were shocked to notice the difference in mackerel availability.

The decline of Boston mackerel isn’t an isolated, one-of-a-kind story. It illustrates a general phenomenon: the difficulty of recognizing slowly unfolding disasters. In contrast, it’s easy for us to recognize sudden disasters that happen overnight. Here in Los Angeles, we were forced to notice the fires that broke out on Jan. 7 of this year, destroyed 20,000 homes and drove my wife and me to evacuate our house. In Japan you notice and respond immediately to tsunami like those in Fukushima in 2011, earthquakes like Great Kanto in 1923, and volcanic eruptions like Sakurajima in 1914. All of us fear such disasters, because they quickly kill many people and cause economic damage in spectacularly visible ways.

But slowly unfolding disasters damage the lives of far more people and cause far more economic damage. Because they aren’t spectacularly visible, we don’t notice them. They don’t get the attention that they deserve. They creep up on us. We do nothing to halt them, until it’s too late.

Exposure to slow declines of resources, like mackerel, is a problem especially for Japan. That’s because Japan is in many respects a resource-poor country. While it has high rainfall, large areas of mountain forest and some fertile soils, in other respects Japan depends on imports. For instance, Japan imports virtually all of its oil, natural gas and metals, and most of its timber.

For animal protein, Japanese people depend more on seafood than do Americans and Europeans. Why is that? The answer is clear: Japan doesn’t devote huge areas to feeding cows and sheep, as do we Americans and Europeans. In the Tokugawa era, when Japan had minimal trade with other countries, Japan was completely self-sufficient in seafood, caught in Japanese waters. Today, because of modern Japan’s much larger population, higher standard of living and increased consumption of animal protein, Japanese fishermen have to catch much fish overseas. Japan imports nearly one-half of its seafood, and its own large fishing fleet accounts for the rest. That’s a big problem, because other countries are also increasing their seafood consumption, China and the European Union also have large competing fishing fleets and modern methods of catching fish are increasingly efficient.

The good news is that depletion of fish stocks by overfishing, as happened to Atlantic mackerel, isn’t inevitable. Unlike metals and oil, fish reproduce. Adult fish produce baby fish; adult coal doesn’t produce baby coal. As long as we catch adult fish at a rate lower than the rate at which the remaining adult fish produce baby fish, fishing is sustainable: It can continue indefinitely.

The bad news: Unfortunately, most of the world’s major fisheries are overfished, declining, yielding fewer fish, are in imminent danger of collapsing or have already collapsed. Even what used to be the world’s largest fishery — the Peruvian anchovy fishery, which at its peak yielded 13 million tons of fish per year — collapsed and hasn’t recovered. In Peru as elsewhere, when fisheries scientists recommended limits on fish catches, fishermen objected to such limits, reasoning: If I don’t catch those fish myself, some other fisherman will catch them.

The many fisheries important to Japanese people include Mediterranean bluefin tuna prized for sushi and sashimi. Because those tuna spawn in large concentrations within small areas of the Western Mediterranean, they are vulnerable to overfishing. Proposals to protect the fishery by limiting the catch were fiercely debated. By 2009, their stock had declined by 72% in the previous four decades. But the future of this fishery, as prized in Japan as was the mackerel fishery in Boston, remains uncertain.

Overfishing isn’t the only slowly unfolding threat to us fish-lovers around the world, including in Japan. Another such threat is global climate change. As the ocean grows warmer, some North Pacific fish species are shifting their ranges further northward, in order to keep living in water at the temperature to which they are adapted. In Japan that means that fish species formerly commonest in waters off Honshu are now shifting their ranges towards Hokkaido. Yes, the waters around Hokkaido are Japanese waters, and Japanese fishing boats can still fish there. But with more climate change, fish now common around Hokkaido will shift still further north — to waters off the Kuril Islands, Sakhalin and Kamchatka. Those are Russian waters, where Japanese fishing vessels may face limitations on access.

Of course, seafood isn’t the only imported resource that poses a slowly developing crisis for Japan. Timber imports from overseas are another potential big crisis. The list continues on from there. How will Japan cope with these threats?

Japan’s recent history suggests an answer. Around the year 1639, the Tokugawa shogun isolated Japan for two centuries, by cutting off most contact with the outside world. That isolation was ended in 1853 by an unwelcome visit from an American fleet under Commodore Matthew Perry. During the Meiji Restoration that began in 1868, Japan’s new leaders had the foresight to realize that maintaining Japanese independence would require quickly adopting Western sources of strength, so as to be able to resist the West and avoid China’s fate. The resulting changes in Japan from 1868 to 1914 constitute the world’s outstanding example of selective change in modern times: acquiring new Western sources of strength, while retaining traditional Japanese sources of strength.

In the last 80 years, Japan has adopted further massive selective changes. No other country in the world has matched that success of Japan. Thus, Japan’s history gives reason for cautious optimism that the Japanese people can once again resolve difficult problems and maintain a prosperous future.

Jared Diamond

Jared Diamond is the Pulitzer Prize-winning author of “Guns, Germs, and Steel,” “Collapse,” “Upheaval,” and other international best-selling books. He was formerly a professor of geography at the University of California, Los Angeles.

The Japanese translation of this article appeared in The Yomiuri Shimbun’s Sept. 7 issue.