Is more fish farming a good thing?

Last year, a team of marine scientists reported that if current fishing practices continue, the world's major fish populations would be effectively extinct by the middle of the century. For the world's wealthy, seafood is an increasingly popular health food option: with its high levels of fatty acids and trace minerals, it's considered essential to the development and maintenance of good neurological function, not to mention reduced risk of cancer, heart disease, and other debilitating conditions. In poorer nations, people are also eating more fish, if they can afford it. For more than a billion people, mostly in Asia, fish supplies 30 percent of their protein, versus just 6 percent worldwide.

In light of these challenges, last week the National Fisheries Institute, the leading advocacy group for the U.S. seafood industry, "spun" a panel on fisheries at the AAAS Annual Meeting in San Francisco, pointing to "the enormous potential for sustainable growth of healthy farmed seafood production, notably through advancements in feed efficiency and the ability to expand production in marine environments."

Sure, fish farming has great potential: it already accounts for 40 percent of the world's seafood, and, according to the UN, global aquaculture production will need to nearly double by 2050 to meet consumer demand. But not all fish farming is created equal. Although farmers have been raising herbivorous fish, like carp, in ponds for millennia, the relatively recent move toward raising tuna, salmon, striped bass, shrimp, and other carnivores in pens consumes a growing share of the world’s wild fish. Known as “forage” fish, species like anchovy, herring, capelin, and whiting are reduced to little more than fish bits to feed fish farms and even livestock. In 1948, only 7.7 percent of global marine landings were used for fishmeal and fish oil. Today, about 37 percent, or 32 million tons per year, is reduced to feed, eliminating an important historical and future source of human sustenance.

The bigger fish don't just eat more seafood, they create more waste and need more space. This is one reason the seafood industry is pushing for fish farming in open-ocean pens, far from the coastal communities that have been protesting polluting fish farms. But open-ocean pens have their own set of concerns, including the possibility of creating hotspots of pollution on the high seas. (I'll get into this more in a future blog post.)

Eating lower on the marine food chain, including favoring herbivorous farmed fish like catfish, carp, and tilapia, as well as oysters, clams, mussels, and sea vegetables, is one of the most important moves a concerned seafood lover can make.