Open ocean fish farms on the horizon?

• Position: Pollution

Innovative submersible fish pens and new developments in fish food may change the way "fish farming" is conducted throughout the world, maintains a report in The Environmental Magazine. Sustainable aquaculture is possible, say some innovative practitioners--and open ocean fish farms may be the solution to a whole range of environmental problems.

These are not the crowded, close-to-shore pens where fish are trapped like caged chickens, requiring doses of antibiotics that leak, along with concentrated wastes, into surrounding waters. They are submersible net pens, more than 150 feet apart, where ocean currents disperse waste, and fish swim and live in the closest possible approximation to their natural habitat--in other words, free-range fish.

Moreover, the food the fish can be fed--developed from soy and microalgae instead of feeder fish like the Peruvian anchovy that underwent a major collapse in the 1970s--has potential for removing fish altogether from the meal equation.

The majority of commercial fishing operations today rely not on fish farming at all but on trawling for their catches--dragging a massive net, up to a football field in length, along the seafloor or midway between the floor and surface. Not only do these nets sweep up desired species such as pollock, cod, flounder, and shrimp, but a significant amount of unsought species--known as bycatch--that die but then get thrown back as waste. Greenpeace International, Amsterdam, Netherlands, reports that bycatch--which can include whales, dolphins, sharks, porpoises, and turtles--could comprise anywhere from eight percent to 25% of global catches.

These operations--along with pollution, ocean acidification, and global warming--have sent wild fish on a dangerous downward spiral, with no signs of recovery. Predator fish--including sharks, swordfish, and cod--already are 90% gone. The United Nations reports that 30% of the world's fish stocks similarly were wiped out and said that, if current fishing rates continue, the world's oceans could be fishless by 2050.

Conventional, large-scale fish farming operations--particularly those on shorelines where fish and their waste are confined--come with serious environmental concerns, too, largely for concentrating pollution in coastal waters. Also, when farmed fish escape, they quickly can upset the ecological balance, such as happened with the blue tilapia, which now is a major threat to freshwater species in the southern Gulf States. This...