By John H. Tibbetts | September 3, 2015
Aquaculture production has more than doubled since 2000, putting pressure on the stocks of small fish used to feed farmed salmon and other species. But researchers are now developing plant-based feeds that could put the industry on a more sustainable path.
In a quiet valley just outside Bozeman, Montana, a trout stream by the name of Bridger Creek flows past a circle of low-rise buildings, including a structure that holds about 250 tanks of rainbow trout in recirculating water. It is here that a plainspoken scientist is helping to lead a seafood revolution.
For years, Rick Barrows, a fish physiologist with the U.S. Department of Agriculture’s (USDA) Research Service, and other scientists have sought to develop all-vegetarian feeds for farmed carnivorous fish such as salmon and trout. Their goal has been to reduce reliance on overfished stocks of sardines, anchovies, and other forage fish, but the scientists have faced considerable hurdles.
As recently as the late 1990s, the aquaculture industry was heavily dependent on marine protein, using about three to four pounds of fish — in the forms of fishmeal and fish oil — to grow one pound of salmon. And the biological challenges of using soybeans and other plants to replace the long-chain fatty acids and amino acids found in forage fish have been considerable.
Now, though, Barrows and his team at the Bozeman Fish Technology Center report that rainbow trout fed a patented all-plant feed, rich in supplemental nutrients, are healthy and grow quickly.
“I was told by many [people] that fish require fishmeal because that’s what they eat in the natural world,” says Barrows. “But that’s just wrong.”
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