Farm raising fish raises questions about water use

Some farmers in Arizona rely on water from the Colorado River, but many others use well water to irrigate crops like alfalfa for the dairy industry or the lettuce, cucumbers and melons shipped nationwide year-round

- Melina Walling, Associated Press

Torks scatter, white against blue water, as Dan Mohring’s pickup truck rumbles down the dirt road. He's towing a trailer full of ground-up beef, chicken, fish and nutrient bits behind him, ready to be shot out of a cannon into the ponds below. It’s time to feed the fish. Mohring fires up the machine and the food flies out in a rainbow arc. Then the water comes alive. Hundreds of thrashing, gobbling barramundi wiggle their way to the surface, all fighting for a piece. Until, in a few months, they will become food themselves.

In the desert of landlocked Arizona, where the Colorado River crisis has put water use under a microscope, Mainstream Aquaculture has a fish farm where it’s growing the tropical species barramundi, also known as Asian sea bass, for American restaurants. Mainstream sees it as a sustainable citerative to ocean-caught seafood. They say chefs and conscious consumers like that the food has a shorter distance to travel, eliminating some of the pollution that comes from massive ships that move products around the world. And they and some aquaculture experts argue it’s efficient to use the water twice, since the nutrient-rich leftovers can irrigate crops like Bermuda grass sold for livestock feed.

“We're in the business of water,” said Matt Mangan, head of Australia-based Mainstream's American business. “We want to be here in 20 years’, 30 years’ time.” But some experts question whether growing fish on a large scale in an arid region can work without high environmental costs. That question comes down to what people collectively decide is a good use of water. In Arizona, some places manage water more aggressively than others. But the whole state is dealing with the impacts of climate change, which is making the region drier and water only more precious.