When you think about how your seafood gets to the table, you’re probably imagining a fishing boat and nets or lobster pots. While some seafood is caught that way, even more of it is farmed. Fish aren’t just a delicious part of a balanced diet. They’re also an important part of the environment, as well as complex creatures who can experience pain and emotions. Unfortunately, many of us view fish as resources rather than sympathetic creatures—which is part of the reason fish farming remains so prevalent.
While fish farming can help produce food for the world, billions of fish are raised and killed for human consumption each year. Like chicken, cows and pigs, they tend to be raised en masse in overcrowded and unnatural conditions. This isn’t just bad for the individual fish. It’s also bad for the environment.
Here’s what to know about fish farming, so you can make positive and sustainable choices.
Understanding fish farming and aquaculture
Fish farms can be found in both freshwater and saltwater conditions. Some fish farms are founded in lakes and the ocean, while others use large artificial bodies of water to encourage spawning. In addition to fish, shellfish and seaweed are also farmed.
Unfortunately, over the last 50 years, we’ve seen a massive increase in farming and killing fish for food: in 1970 the global seafood and fish production was about 64 million tons. By 2013, it was 154 million tons, and now more than half of seafood production comes from farming. Aquaculture is the answer to factory farms on land, at least in terms of scale. It’s estimated that hundreds of billions of fish and shellfish are killed each year, worldwide.
If you’ve heard about the overfishing problem and are familiar with the sustainable seafood watch, you know that certain seafood varieties are especially popular—and especially vulnerable. Carp, catfish, tilapia, salmon and trout are all commonly farmed fishes, whether in fresh or saltwater.
There are three main types of fish farming: cage systems, irrigation pond systems and integrated recycling systems. Cage culture systems keep the fish in underwater enclosures, often too packed to freely swim around. The cages are kept in rivers, lakes or the ocean, and may be anchored down. The fish are confined, but the water flows through the open cages.
Irrigation pond systems, also known as irrigation ditch systems, keep the fish in an enclosed body of water. The system might be kept in an irrigation ditch so waste product can be used as fertilizer, or in a self-sustaining pond where food for the fish is grown alongside the fish themselves.
Integrated recycling systems—also known as aquaponics—the fish are kept in plastic tanks inside greenhouses. The wastewater is used to encourage plant growth without soil. Plus, the plants can clean the water, so it can be reused for the fish. The problem is that this can also introduce E.coli into any produce grown with fish wastewater.
There’s also fry farming, which releases juvenile fish into the wild so they can continue to grow—and be caught later.
Environmental effects of fish farming
Even if you’re not convinced that fish can feel emotions and pain, fish farming is a harmful practice. First, the conditions often do not provide an environment conducive to growth and positive welfare. One reason for this is that fish farms foster wild species, who are not suited to living in underwater cages or smaller bodies of water. For example, the average Atlantic salmon travels hundreds of miles when they’re not held in captivity.
Fish farms can put extra pressure on the environment, too. For example, fish farming requires that forage fish like anchovies, herring and sardines are fished and used for farmed fish food. Plus, the overcrowded space leads some fish to suffer stress and premature death, while the water quality suffers.
Those overcrowded environments are also a breeding ground for parasites and diseases, especially when the water quality is bad and the fish are stressed. In turn, the diseased fish can infect wild fish populations.
Finally, the effect on the overall ecosystem is staggering. Overcrowded farms can lead to biodiversity loss, the release of hazardous chemicals and nutrient pollution. The more waste there is, the more polluted the water may be, leading to harmful algae blooms.
In the end, fish are still an excellent source of lean protein, omega-3 fatty acids, vitamin D and other nutrients. You don’t have to cut out fish entirely, however—just look for fish that are wild-caught or raised in an ethical aquaculture environment.
