Until recent times, wild caught fisheries supplied the bulk of our global seafood needs, with aquaculture supplementing global supplies. But by 2013, global aquaculture production exceeded edible wild fish production for the first time.
On an annual basis, Americans eat about 16 pounds of both farmed and wild-caught fish, most of which (91 percent) is imported and some of which is from unsustainable sources. Domestic aquaculture offers this country the chance to produce clean, safe seafood that is fresh and abundant. But in order to meet national needs, the industry must grow in a way that is environmentally friendly, produces very little waste and prevents potentially diseased or invasive fish from escaping into nearby waters - all problems identified with current large-scale production forms of aquaculture.
Enter recirculating farms.
What Are Recirculating Farms?
Recirculating farms are closed-loop, land-based systems that use constantly-cleaned water to raise fish and grow food. There are three categories of recirculating farms:
- Hydroponic systems grow plants in nutrient rich liquid, without what we traditionally think of as soil ("dirt"). Nutrients are added to water. Plants may grow directly in the liquid, the liquid might periodically be sprayed on plants roots or it might flow by the roots as the liquid is recirculated in the system. Some farms use sand or gravel beds to support the plants as they grow.
- Recirculating fish farms raise fish in tanks that have a water filter system to clean the water for constant reuse, just like an aquarium at home.
- Aquaponic farms are a combination of aquaculture and hydroponics - where fish are raised in tanks and the water from the fish tanks circulates into the plant beds so the plants can absorb nutrients from the fish water. Then the water is returned from the plant beds, cleaner, to the fish for reuse.
The infographic that accompanies this post illustrates how each system works.
What Can You Grow in Recirculating Farms?
Recirculating farms are incredibly versatile in terms of what can be grown and raised.
Systems around the country are producing many vegetables and herbs, along with some fruits and flowers, including:
- Herbs like basil, cilantro, mint, chives and parsley;
- Greens like bok choy, lettuce, chard, kale and spinach;
- Root veggies like carrots and green onions;
- Other veggies like snap peas, peppers, eggplant, squash and tomatoes;
- Fruit like melons and strawberries; and
- Flowers like jasmine and honeysuckle.
Recirculating fish farms and aquaponic farms are capable of raising both freshwater and saltwater fish including:
- Freshwater fish like eel, tilapia, yellow perch and catfish;
- Saltwater fish like sea bass and cobia;
- Shellfish like crabs, oysters, shrimp, prawns and crayfish; and
- Ornamental fish like goldfish and koi.
Recirculating farms offer us a chance to produce vegetables, fruits and/or fish that are clean, fresh, local and abundant - all of which adds to the sustainability and resilience of our local food systems. The next time you're wondering what fish to order, if there's a local choice, make it. There's even a chance it came from a recirculating farm.