Writer Paul Greenberg has been eating fish caught in local waters since he was a kid growing up in Connecticut. Most of the fish he caught himself — but occasionally, he would visit the fishmonger in his hometown and purchase wild fish, fresh from the sea.
But when he visited fish markets as an adult, he realized that the types of fish for sale had changed. Instead of a variety of wild-caught fish, Greenberg saw four varieties of fish — salmon, sea bass, cod and tuna — that seemed to consistently be on fishmongers' shelves, despite having little to do with the waters adjacent to his local fish market.
In his new book, Four Fish: The Future of the Last Wild Food, Greenberg investigates how those four fish came to dominate the seafood market, and examines how the wild fish industry has changed in the past three decades as the business of fishing became more industrialized.
"Fish were different 35-odd years ago, when I was a kid, and I would often visit fish markets no matter where I was," he explains to Fresh Air's Terry Gross. "By and large, what we would see would be entirely wild fish. Forty-odd years ago, everything we ate from the sea was wild. Pretty much everything. Today almost half of what we eat is farmed. So it's a huge, huge shift."
On domesticating wild fish
"The way humans have used fish, we started inland and moved further and further offshore. Salmon represent that first step. Salmon spawn in freshwater rivers. They're nearby. And we have this very close interaction with them where we live. So they were one of the first fish that we really hit hard with industrialization. Dams and pollution and all of these different things caused wide-scale extirpation of salmon, particularly Atlantic salmon, throughout their range. And now what we've seen is, salmon was really the first large-scale domestication project for the fish that we eat. There are many more farmed salmon in the world than wild salmon, and it's a kind of replacement of a wild-food system with a domestic-food system that has started to kind of be kind of a model moving forward."
On the salmon's diet, and how it's changed
"What do salmon eat? Well, on the farm what they eat is other fish. And where do those fish come from? The wild. So the global catch right now in the world is 90 million tons, which is a lot. It's equivalent to the human weight of China removed from the sea every year. A third of that is what they call forage fish — herring, anchovies, little things like that. And incidentally, the weight of all of those taken out of the sea every year would be the equivalent of the human weight of the United States taken out every year. Those are harvested every year. They're made into feed pellets. And in the early days of aquatic agriculture, the feeding was extremely inefficient, there wasn't a great deal of care to make sure the salmon actually ate what they were fed. So there was a lot of waste, and I think in 2000, the journal Nature published a study that the fish-in, fish-out ratio ... could be as much as three pounds of wild fish to make one pound of salmon. ... That's a pretty screwy equation. Why are we coming up with a net marine protein loss?
"But to its credit, the salmon industry took this very seriously. ... It's also an economic factor for them — it's expensive buying all of that feed — and over the years, they've instituted a selective breeding program with salmon, mostly in Norway. They took the 40 original salmon strains in all of these different rivers in Norway, and they crossed them and they recrossed them, and they came up with eventually with a salmon that required half the original feed of the original wild variant. ... But the industry keeps growing. So while per-fish efficiency is better, the overall footprint of the salmon industry is just bigger and bigger."
On cod (and the fish stick)
"What cod represents is sort of this epic industrial move to the continental shelves, where, beginning around the Middle Ages, huge aggregations of cod were found, first off of Europe. But then people ... would posit that that's what brought the Vikings to the New World in the first place. There were these huge amounts of cod on the Grand Banks in Canada and then off of Massachusetts. They sort of represent the industrialization of fishing. If all of that cod hadn't been found, I don't think we'd have a fish stick today. And it's the sort of re-imagining of fish — not as this local, artisan product but as this mass-scale, industrial thing that fills up our supermarkets and our fast-food restaurants."
On tilapia vs. other fish (and beef)
"I think it's kind of a neutral fish. Tilapia — because they don't eat a lot of fish meal, they don't fit the omega-3 profile that so many nutritionists say we should be having. That said, as a form of protein, it's better — I think — to eat a low-fat fillet than a big chunk of beef or even pork or chicken. It's just leaner. ... Overall, I eat tilapia. In the profile of food we have to eat out there, I think it's certainly a better choice than beef."