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 for farm-raised species. Salmon—one of the most popular farmed species in the world—is a carnivore, eating over three pounds of wild fish for every pound of weight it gains. Tuna takes over 15 pounds of feed for every pound it gains.

Developing Alternative Diets

There's good news: not all fish are carnivores. Some fish like catfish and tilapia can be raised on diets with very little or no fishmeal or fish oil. These alternative feeds take pressure off wild fish populations. They're good for fish farmers, too, costing much less than fish products. Shellfish (like mussels and oysters) are another good option. These animals feed by filtering particles out of the water and can be easily farmed in clean water where they collect their own food and don't require supplemental food.

Ranching Wild Fish

In a recent trend, fish farmers have become "ranchers." Instead of raising fish from eggs, they take large numbers of small, young fish from the wild and grow them for eventual sale. In one instance, young eels are caught and then farmed to supply unagi to sushi bars, a practice that has led to depleted wild stocks. Young bluefin tuna are also being caught and ranched in operations that are both highly profitable and resource intensive—further impacting depleted populations.