Is it OK to eat farmed fish? Here’s what you need to know

Billingsgate Shellfish oyster beds off of Old Wharf Point. (Jesse Costa/WBUR)
Billingsgate Shellfish oyster beds off of Old Wharf Point. (Jesse Costa/WBUR)

Let’s face it: farmed fish has a bad rap. And, there are some good reasons for that.

Let’s take a quick look at shrimp, for instance. Shrimp makes up about a quarter of the seafood market in the U.S., and almost all of it (90%) is imported.

Farmed shrimp is poorly regulated or unregulated in much of the world. This has led to mangroves being clear-cut for shrimp production, and shrimp farms dumping their filth into local waters. Plus, farmed shrimp may be treated with antibiotics, insecticides and preservatives before ending up in your shrimp cocktail. And some farms use child labor. Wild shrimp isn't always a safe bet either; trawling for wild shrimp, done badly, can tear up the seafloor and harm ecosystems.

But there are more eco-friendly ways to grow shrimp. The Mexico-based Atarraya, for instance, makes a shipping-container-based shrimp farm called  “ShrimpBox” which sidesteps many of these issues. The company grows shrimp without antibiotics, often using renewable energy, and in cities close to the food's final destination.

But it can be hard for consumers to puzzle through the choices. What’s better for the planet? Wild caught fish or shrimp-in-a-shipping-container?

Well, no need to flounder, we’ll fish through this together! Here are answers to all your questions about farmed fish.

Are there fish farms in New England?

Yes. Mostly shellfish, but also seaweed, salmon and other seafood. (Like this salmon farm in Maine that got whacked by hungry seals.) A few stats:

What do fish farms look like?

It varies by fish. Salmon farms are usually huge circular net pens in the ocean, shrimp are often grown in coastal ponds. Monterey Bay Aquarium’s Seafood Watch has good descriptions of all these aquaculture methods.

I’ve heard that fish farms actually feed fish meal to other fish. Is that true? That seems gross.

Some of the most popular farmed fish — including Atlantic salmon and steelhead trout — are carnivores. In the wild, they eat stuff like krill, insects, other fish and even mice (!) on occasion. Replicating this diet on a farm means fish food is made with fish meal and fish oil.

Why does it matter what fish food is made from? 

Feed is a major climate and sustainability challenge for aquaculture.

“Seventy, 80, 90% of the carbon footprint of the salmon is typically associated with the feed,” says Robert Parker, senior coordinator for greenhouse gas emissions at the Aquaculture Stewardship Council. “If there’s Peruvian anchovy meal in the feed, how much fuel did those Peruvian anchovy fisheries burn in producing that?”

There's another issue, too, says Chris Golden, an associate professor of nutrition and planetary health at the Harvard T.H. Chan School of Public Health. He estimates 90% of fish meal and fish oil comes from food-grade fish, sometimes from developing nations, which can raise environmental justice concerns, he said.

Are there more eco-friendly ways to feed fish?


Todd English, VP of Sustainability for Riverence Provisions in Idaho, the largest rainbow and steelhead trout producer in the Americas, says most of the fish meal they use is made from fish heads, guts and other scraps. In general, consumers are not demanding to eat these. (Yet!) He said Riverence is constantly trying to develop more sustainable feed, using ingredients like fly larvae and algae-based omega-3 oil.

Fish farmers also swap out fish meal for vegetable proteins, like soy. But even that can be problematic, depending on the source. For instance, soy meal from Brazil can have a large deforestation impact; soy from the United States, not so much.

Some food for thought: oysters, clams and kelp don’t require any feed.

I’ve heard that salmon raised in ocean pens can cause a lot of water pollution. True?

Yes, sometimes.

Farmed salmon are often raised in large ocean pens, which look like huge cylindrical underwater nets. Opponents of ocean pens say the system leads to food waste and fish poop piling up on the ocean floor; fish parasites like sea lice escaping from the penned fish and infecting wild ones; and chemical additives and pollution escaping into the ocean. Excess nutrients from fish poo and uneaten food can also lead to an overgrowth of algae that can choke local ecosystems.

“Fish farming in the ocean is simply taking a factory farm on land and putting in the water,” says James Mitchell, legislative director with Don’t Cage Our Oceans, a coalition opposed to the spread of industrial-scale offshore fish farming. “It has all the same problems,” he added.

Are there more eco-friendly ways to raise fish in ocean pens?


Best practices for ocean pen farming include regular testing of the water and seabed for pathogens and pollution, avoiding the preemptive use of antibiotics, and not building farms in environmentally sensitive areas. In Norway — one of the world’s leading producers of Atlantic salmon — the area around a pen is allowed to recover after harvest.

Still, opponents like Mitchell argue allowing the pollution to wash away creates environmental justice issues. “That pollution becomes essentially somebody else’s problem.”

What about raising fish in ponds along the coast? Is that bad?

It can be.

Historically, people often built ponds for raising shrimp and other crustaceans along coastlines, sometimes destroying mangroves to do so. Discharging untreated water from the ponds can pollute the surrounding ecosystem and water supplies.

What about raising fish in tanks? Is that eco-friendly?

It can be.

Many experts say recirculating tanks are a better choice than ponds. These are land-based pools or tanks where —  ideally —  water is used for multiple production cycles before being treated and discharged or evaporated.

Some farmed fish can even be a food justice solution! The New Orleans-based nonprofit Recirculating Farms helps residents of urban neighborhoods establish small farms that grow fish and plants in one constantly-cycling loop of water. The fish poop feeds the plants; the plant roots clean the water and you end up with local, sustainable food.

On a commercial scale, Riverence Provisions raises rainbow and steelhead trout in long tanks called raceways. The poop and extra feed is vacuumed up, dried and given to local farmers to use for fertilizer.

Do farmed fish have lower greenhouse gas emissions than beef? What about pork and chicken?

Seafood is generally more climate-friendly than many land-based animal proteins, especially beef and lamb.

That’s partly because fish turn their food into biomass more efficiently. It takes 1-2 kg of feed to make 1 kg of fish, and more than 6 kg of feed to make a single kilogram of beef. (This is partly because fish spend less energy swimming than land animals do moving around.)

Farmed fish also tends to beat pork in this “feed conversion ratio” — and is comparable to chicken.

Do farmed fish have lower greenhouse gas emissions than wild-caught fish?

It depends.

Wild-caught fish have one big sustainability advantage over farmed fish: they don’t require any “inputs,” like feed or medicine. For wild-caught fish, the carbon footprint comes from the gas used to power the boat, and the fuel used to transport the fish.

But there’s a huge variation in carbon footprints among commercial fisheries, so wild-caught doesn’t always win the carbon footprint game. Take lobster, for instance.

Lobster boats burn a relatively high amount of fuel to catch relatively few crustaceans with little edible meat, said Parker. If you’re eating locally caught lobsters in New England, the carbon footprint is OK, he said, but flying them to China sends their emissions way up.

The U.S. exported more than 13 million pounds of lobster to China in 2021— mostly from Maine and Massachusetts — despite ongoing trade disputes.

What are some tips for eating farmed fish sustainably?

  • Eat local shellfish and locally-farmed seaweed.
  • If you gotta have that Atlantic salmon or other farmed fish, look for a label from a third-party certifier. The biggest and best is the Aquaculture Stewardship Council (look for their teal fish label).

What are some tips for eating wild fish sustainably?

  • Between 70-85% of the seafood eaten in the U.S. is imported. These food miles add to seafood’s carbon footprint, as I explained in my  “Cooked” newsletter on wild-caught fish. So eat local fish and learn to be creative about cooking less common options. You can search the Local Catch Network’s seafood finder for area suppliers.
  • Eat small, oily “pelagic” fish like herring, mackerel, sardines and anchovies. They’re plentiful, cheap and nutritious.

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Barbara Moran Correspondent, Climate and Environment
Barbara Moran is a correspondent on WBUR’s environmental team.



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