In a capacious warehouse northeast of downtown Bozeman, a lanky scientist named Rick Barrows leans over a blue tank teeming with rainbow trout. The fish thrash expectantly at the arrival of human visitors, and Barrows smiles behind his scrub-brush mustache.
"You go to the poultry nutrition conference, and there are 4,000 people there," he says wryly. "You go to the U.S. fish nutrition conference, and there are 30."
Rick Barrows is a U.S. Department of Agriculture fish nutritionist—an esoteric occupation, true, but a vital one. Here at the Bozeman Fish Technology Center, a century-old federal facility tucked into a patchwork of ranchlands, Barrows is changing how the world produces its seafood.
Aquaculture is the fastest-growing form of food production in the world, at around 8 percent per year; the World Bank projects that two-thirds of our fish will come from farms by 2030. From a sustainability standpoint, that might be good news. Because they're cold-blooded and water-dwelling, fish don't have to heat their bodies or support their own weight. That means they can devote calories to packing on muscle, making them a more efficient source of protein than four-legged livestock.
"Aquaculture is most likely to meet the growing demand for animal products with the least demand on ecosystems," one Conservation International official told The Guardian in 2011.
But aquaculture carries plenty of ecological baggage. Perhaps its greatest irony is that growing fish on farms has traditionally required extracting other fish from the sea. Well over half the global harvest of so-called forage fish—the small silver creatures, like sardines, menhaden and anchovies, that form the bedrock of marine ecosystems—gets ground into fishmeal and fish oil to feed bigger farmed species, like salmon.
The West is hardly immune to the repercussions. Pacific sardines have experienced a nearly decade-long collapse, starving brown pelicans and California sea lions and prompting federal managers to close the fishery in July 2015. While sardine stocks are notoriously prone to natural boom-bust cycles, fishing pressure appears to have exacerbated this crash.
To avert ecological harm—and defray rising costs—fish farmers have lately begun reducing the proportion of fishmeal in aquaculture feed, replacing ground-up sardines and anchovies with soybeans and corn. The challenge is that many delectable fish, such as salmon and trout, are carnivores, ill-adapted to subsisting on vegetable matter.
Thanks in large part to Rick Barrows, however, some companies are already raising carnivorous fish on all-plant diets. For over two decades, Barrows has been developing vegetarian feeds for species such as salmon, cobia, walleye and, most of all, trout.
"We consider rainbow trout the white rat of the aquaculture world: They grow fast and they're inexpensive to obtain," Barrows says as his fish churn the surface. "We use trout to develop basic dietary knowledge that we apply to other species."
The future of seafood, in other words, is being developed with the help of freshwater fish, 600 miles from the nearest ocean.
From one perspective, farming carnivorous fish doesn't make much sense. The planet is swimming with herbivores and omnivores that require less protein-dense meals. Tilapia, which flourishes on a chickenfeed-like corn diet, is the country's fourth most-eaten form of seafood, though its popularity hasn't come without environmental consequences, such as pollution and ecosystem invasions.
But carnivores have a crucial physiological advantage over their plant-eating counterparts.