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A Bountiful Harvest Still Depends On the Sea

While farmed fish and shellfish can supplement our seafood supply, they can't replace the variety and abundance of seafood from the wild. Some fish farms still depend on wild populations to supply eggs or juveniles that the farmers raise for market. Many fish farms also depend on wild fish, like sardines or anchovies, as food for the farmed species.

Some Fish Are Carnivores

Every year, millions of tons of wild fish, like sardines and anchovies, are caught and processed into fishmeal and fish oil, which is used to make feed for farm-raised species. Some of these species, like salmon—one of the most popular farmed fish in the world—require over a pound of wild fish for every pound of weight they gain. Tuna requires over 15 pounds of feed for every pound it gains.

Developing Alternative Diets

There's good news: not all fish are carnivores. Some, like catfish and tilapia, can be raised on diets with very little or no fishmeal or fish oil. Shellfish (like mussels and oysters) are another good option. These animals feed by filtering plankton out of the water and need no supplemental food.

Ranching Wild Fish

Some fish farms operate as "ranches.” Instead of raising fish from eggs, they take large numbers of fish from the wild and grow them for eventual sale. Not only do these farms still rely on wild populations, in some cases the fish they take are still juveniles. For example, young eels are caught and then farmed to supply unagi to sushi bars. Similarly, young bluefin tuna are ranched for highly-profitable but resource-intensive industry. This practice has contributed to the depletion of wild stocks of both of these species.

What You Can Do

Search for Sustainable Seafood 

Farmed oysters, clams and mussels are an excellent choice. Most oysters on the U.S. market, and many clams and mussels, are farm-raised. These shellfish do not require supplemental feeding. They can even improve water quality!


Story of Hope

Innovations in Aquaculture Feeds

One of the biggest issues facing aquaculture is its dependence on wild fisheries for fishmeal and fish oil, which are used to feed many farmed species. The high cost of fishmeal and fish oil—as well as their limited availability—is encouraging the development of alternative feeds. Protein from plants, like soy and grains and from byproducts of seafood and livestock processing, can replace protein usually obtained from wild fish. Many of the major feed manufacturers are investing heavily in development of these alternative feeds and some fish farmers have found success using them.
Learn about wild seafood Related ocean issue resources