(above photo © NOAA)
Aquaculture—fish farming— is a large and growing industry that could soon outpace wild fish production. In 2012, aquaculture produced an estimated 66 million metric tons of food fish, worth $138 billion. For comparison, commercial fishing hauls in 90 million metric tons of wild-caught fish annually.
Aquaculture has the potential to take pressure off depleted wild fish populations, while providing food and nutrients to millions of people. Sound like a great solution? Actually—it’s complicated.
How ‘sustainable’ fish farming is depends on which species are being farmed, what they are being fed, and where the farming is taking place.
Unsustainable Fish Farming
Some farmed species such as Atlantic salmon are problematic. When salmon are farmed in open-ocean net pens they may escape and threaten native species with diseases or parasites. And when farmed, carnivorous species like salmon are fed large quantities of wild caught forage fish, we risk depleting the forage fish, which are needed as food for wild predatory fish and other marine animals.
Shrimp farming also requires the use of wild fish. In addition, the vast majority of shrimp farming occurs in tropical nations where shrimp farmers destroy important mangrove forest habitats and pollute coastal waters. (Note: Shrimp farming in Southeast Asia has also been linked to slave labor.)
Sustainable Fish Farming
What are some sustainable farmed options? Farmed catfish and tilapia are increasingly popular with seafood lovers and can be a smart alternative when raised in closed systems where wastes are controlled and there is little chance of the fish escaping. These fish are also fed a vegetable-based diet such as corn and soy-based feed.
Farmed mussels, oysters and clams are highly sustainable choices. They are grown in coastal waters in a similar manner to the way their wild counterparts grow, and require no external feed. They feed by filtering phytoplankton (or free-swimming algae) right out of the water, and in doing so they actually help to clean coastal waters. Bonus: they are high in health-promoting omega-3s and low in mercury!
What You Can Do
When it comes to eating farmed fish make informed choices. We recommend Monterey Bay Aquarium Seafood Watch’s Farmed Fish Rankings. Our business partner Whole Foods Market also has robust sustainability standards for farmed fish.