It began more than 20 million years ago, when the Earth's crust, stretched thin along the floor of a growing rift valley, unleashed immense outpourings of lava. In a series of cataclysmic events, 15,000 square miles of what is now the part of the American West from Yellowstone to Oregon were buried beneath thousands of feet of molten rock.
Today, this arid landscape is dotted with sagebrush and dissected by deep ravines and canyons. Named after the stream that etches a serpentine line across its length, Idaho's Snake River plain gives little hint of its fiery past--or of the wealth that lies below.
Drawn from rain, snow and rivers, and secreted in fractures and tiny pockets of the porous volcanic rock, a vast store of water lies beneath the plain. This underground river moves covertly until interrupted by the Snake River valley, a 40-mile stretch of river-cut cliffs. Here, in torrents and trickles, more than a million gallons of water a minute spring and seep from sheer rock walls. The water is crystal-clear, well oxygenated, a near-constant 58 degrees--and a trout farmer's dream come true.
The region's potential for aquaculture was first recognized in 1928, when several small trout farms were built in the valley. More farms were added in the years following World War II. Today, three major producers and more than 75 small contract growers harvest more than 40 million pounds of rainbows annually. Clear Springs Foods, the world's largest trout farm, began production in 1966 and now accounts for nearly half of that total.
Trout have been cultured since the 14th Century, when a French monk discovered that their eggs could be artificially impregnated. But nearly 400 years passed before the world's first trout hatchery began operating in France. Initially, efforts focused on repopulating natural waters for sport fishing. Beginning in France, Denmark and Japan, trout farming spread throughout the world, arriving in the United States in 1864 with the building of a hatchery in New York state.
The culinary attributes of trout inevitably led to farm-raised fish destined for commercial markets. Today, rainbow trout are found on every continent but Antarctica and are among the most widely farmed fish in the world. Rainbows are farmed in all 50 states, but about 80% of the nation's production comes from the waters of Idaho. The Snake River Valley is one of the great success stories of aquaculture.
At first, aquaculture might seem forbiddingly high-tech. But this is farming. The only difference is that the feedlots are filled with fish instead of cattle. Idaho trout farmers rely on an abundance of high-quality water and use gravity-fed raceways--narrow, concrete-lined pools that channel the water--to hold the fish until maturity in an easily controlled environment.
There are many advantages to farming fish over hunting them. Fish farmers can easily manage each stage of the fish's life. Through selective breeding they can influence the size and even the sex of the fish. Rigorous attention to food and environmental conditions help to control growth rate. Because trout farmers can plan production to meet market demand, their fish can arrive very fresh, with little time spent in holding, processing or transport. The end result is reasonably priced fish, available year round, that are consistent in size, flavor and quality.