The Fish That Feed Your Fish: What Farmed Salmon Really Eat

Mowi is the largest farmed salmon company in the world. Its name comes from Thor Mowinckel, who co-founded the company in Norway in the late 1960s. Frederik W. Mowinckel, a relative from that same family, has become one of the industry’s sharpest critics. In 2018, members of the family voted against Marine Harvest renaming itself Mowi, saying they did not want their name tied to what they considered an unsustainable way of farming salmon.

In an interview with The Outlaw Ocean Project [VERIFY date], he asked how it can be sustainable to take fish from poor countries, grind them up, ship them halfway around the world, and feed them to salmon eaten by people who are far better off.

When someone whose family name is on the company asks that question, it deserves an answer. This week on How to Protect the Ocean, we’re following farmed fish from your plate back to the boat, and the answer starts with the numbers.

Most farmed seafood has to be fed

In 2022, fish farms produced 51% of the world’s aquatic animal food, overtaking wild capture for the first time, according to the UN Food and Agriculture Organization. About two-thirds of farmed fish, including salmon, shrimp, trout, sea bass and sea bream, are raised on pellets made partly from wild fish.

The result surprises most people. About a fifth of the global wild catch, roughly 18 million tonnes a year, goes to uses other than feeding people directly, mainly fishmeal and fish oil. When we picture overfishing, we picture fish on dinner plates. A large share of the catch goes to farms first.

When I studied at the University of Guelph in the late 1990s, my aquaculture professor told our class that fish farms would one day supply half the world’s seafood. I didn’t believe him. He was right. Nobody in that room talked much about what those farmed fish would eat, or who would pay the price.

What fishmeal is made of

Fishmeal is a dark yellow powder made by cooking and grinding small fish such as anchoveta, sardinella and herring. Fish oil is the liquid version. A 2017 study in the journal Fish and Fisheries found that roughly 90% of the fish turned into fishmeal are food-grade, meaning people could eat them directly. In many coastal communities, people did.

The Outlaw Ocean Project’s five-year investigation found that at least half of the species landed by the fishmeal vessels it assessed are classified by scientific studies as overexploited or worse. That list includes sardinella off Senegal, oil sardines in India and anchoveta in Chile. These small fish sit near the base of the food web, feeding tuna, seabirds, whales, sharks and people.

Forage fish are already under pressure

Forage fish declines are showing up in fisheries everywhere. In Atlantic Canada, the 2022 herring quota for the Bay of Fundy and southwest Nova Scotia was cut by a third, from 35,000 tonnes to 23,450, after the stock fell deeper into the critical zone. The same year, Canada closed its Atlantic mackerel fishery entirely.

These are the same kinds of small, oily fish that fishmeal boats chase around the world. Fishmeal demand adds one more mouth competing for them, and climate is adding pressure too. In 2023, El Niño forced Peru, which produces about a fifth of the world’s fishmeal and fish oil, to cancel a major anchoveta fishing season. The El Niño building in the Pacific this year is forecast to be very strong, and more frequent events leave less time for stocks to recover in between.

How many wild fish does one farmed salmon eat?

Scientists disagree on the exact figure. Some research argues the industry undercounts its wild fish use. Other researchers say critics rely on old data from when feeds contained far more fish. Everyone agrees on one point: fish farming depends on wild fish.

Why changing the feed is so hard

Alternatives exist, and they’ve struggled. French company Ynsect built what it called the world’s largest insect farm in Amiens, in northern France, to turn mealworm larvae into protein for animal feed. Investors put in more than half a billion dollars. The farm entered service at the end of 2022, the same year the company lost nearly 90 million euros. In 2023, Ynsect shifted its focus away from animal feed toward higher-margin pet food. By 2025, it was in liquidation and the Amiens plant was closing.

Scale is the core problem. Aquaculture uses close to 4 million tonnes of fishmeal every year, more than three-quarters of global supply. Even optimistic forecasts for insect protein reach only a few hundred thousand tonnes.

Norway shows feed can change

Norway proves progress is possible. In 1990, about 90% of Norwegian salmon feed came from marine ingredients. Over 30 years, researchers swapped most of it for plant ingredients, and by 2020 marine ingredients made up 22.4% of feed, according to the Norwegian research institute Nofima.

The catch is growth. The industry expanded enormously over the same period, and 91.7% of Norway’s salmon feed ingredients are now imported. Analysis from the FAIRR Initiative, an investor network, found that five of the world’s top seven salmon producers increased their total use of fishmeal or fish oil made from whole wild fish between 2020 and 2024, by as much as 39%. Each pellet contains less fish, and the industry now produces far more pellets, so total pressure on wild stocks keeps rising.

The fix at the seafood counter

Farmed seafood has a second family: mussels, oysters and clams. They eat plankton straight from the water, and nobody feeds them anything. University of Cambridge researchers, publishing in Nature Food, estimate that new advances in bivalve farming could meet the protein needs of nearly a billion people in the world’s most vulnerable regions.

Yet the share of aquaculture that needs no feed has been shrinking, from about 44% of farmed aquatic animals in the early 2000s to about 30% by 2018. Every bivalve meal helps push that share back up, and more demand for mussels, clams and oysters means less demand for fed fish and the forage fish ground into their pellets.

Picture a mussel hanging in cold water, filtering it clean as it grows. Nobody went hungry to feed it, and you still get a protein-rich meal. Some of the best seafood on Earth asks nothing of the ocean except to be left alone.

This week’s action: swap one farmed salmon or shrimp meal for farmed mussels, oysters or clams.

Takeaways

• In 2022, farms produced 51% of the world’s aquatic animal food, and about two-thirds of farmed fish depend on feed made partly from wild fish.
• About a fifth of the global wild catch is turned into fishmeal and fish oil, and roughly 90% of those fish are food-grade.
• Forage fish are already stressed by overfishing and climate events like El Niño.
• Insect protein and other alternatives can’t yet match the scale of fishmeal demand, and Europe’s flagship insect farm has gone into liquidation.
• Norway cut fish content in salmon feed from 90% to 22% over 30 years, yet major producers’ total wild fish use rose between 2020 and 2024.
• Farmed bivalves need no feed and are one of the most ocean-friendly seafood choices you can make.