The Hotchkiss National Fish Hatchery, located in west-central Colorado about 50 miles southeast of Grand Junction, has been a major producer of Cutthroat and Rainbow trout since 1967, raising over 130,000 pounds of fish per year to use for stocking primary reservoirs and an occasional river or stream.
According to Assistant Project Leader David Oviedo, the process begins after the hatchery receives fertilized eggs, via Federal Express, from various Broodstock facilities in Colorado, Montana and Tennessee. “The eggs are about two weeks old when they arrive here, at the stage where you can see the little eyeballs inside,” he says. Emptied into the incubation jars which have been filled with gravity-fed, pure spring water, the “50 to 75,000 eggs (per jar) are kept in constant motion during incubation. This helps to maintain a steady oxygen supply and inhibits fungus growth.” Once the tiny newborns emerge they are referred to as “sac or yolk fry” because of the enlarged yolk sack that supplies nourishment to them.
All indoor tanks and outdoor raceways utilize the spring (as opposed to river) water, and that is what makes the Hotchkiss facility unique. According to one of the many educational brochures that the Hatchery has on display, the spring “was created in the 1930s by an earthquake near Salt Lake City, whose tremors also affected the Hotchkiss area. It has a constant temperature of 56 degrees and flows from 2,200 to 5,000 gallons per minute.” Because of the nitrogen gas in that water, liquid oxygen is injected into the in-flowing supply before it reaches the eggs and fish. “This prevents nitrogen gas bubbles from forming in their bloodstream,” David explains, “compared to what would happen with a human diver when he is in deep water and comes to the surface too fast.”
As the fish mature, they are moved from the 24 indoor nursery tanks into one of the 40 concrete raceways outside to complete their growth to the required stocking size. The nutritional requirements vary according to that length, since “Protein levels must be higher for the smaller ones.” He continues, “Biologists and fish nutritionists developed the diet. Some of the wilder strains of trout even get krill, or ground-up shrimp, mixed in since it’s easier for them to utilize natural food than what has been processed.” David dipped his hands into a few bags, bringing up samples in order to illustrate the difference. “Small fish are fed starter and crumble-type feed. The larger fish get feed pellets. The circumferences range from 1.0 millimeters (mm) to 4.5mm. Anything 2.5 mm and up will float on the top of the water, so we give that to the bigger fish. The smaller sizes are slow-sinking. When we toss in the food, we watch. If the fish don’t eat, we know that something might be wrong. Is this tank overcrowded? Could something be getting them sick?” To help keep the fish healthy, salt baths are used to strip bacteria from the gills.
Another thing that the Hatchery employees watch for is Whirling disease, which originated in Europe and was introduced into the United States by German Brown Trout, brought to Pennsylvania in the 1950s. Since then, it has been slowly spreading towards the West. “It affects the young trout before they reach the 4-inch length stage, when their skeletons are still mostly cartilage,” David says. “It can result in deformities which in turn interfere with their sense of balance. This causes the fish to swim in a corkscrew motion instead of straight, making them easy targets for predators.” During the annual inspections each February, blood, kidney and liver samples are taken from various strains and meticulously recorded and, David points out, “We have ALWAYS been free from Whirling disease.” Even the healthiest and strongest of adult fish are not entirely free from danger however, since predators are constantly lurking close by. “Herons and raccoons are the worst”, he admits, and the Hatchery has sturdy gates that are closed each night to protect the trout in the outdoor raceways. There is additional wire across the top in order to prevent flying predators from grabbing free meals, also.
Angling is a big business in Colorado, generating extra dollars through the sales of rods, reels, lures, hooks, lines, bait, boats, fuel and camping equipment. Trout are hauled to reservoirs by specially-designed trucks, with mule strings occasionally getting used depending on the remoteness of the area. To keep up with supply and demand, David and the rest of the crew at Hotchkiss National Fish Hatchery maintain a detailed and constantly updated “Projected Stocking” board in order to track the number of the fish under their care. As an example, he points to one line and translates, “Currently, we have 39,600 fish of this specific strain on hand that are 4.44-inches long. We have to project the needed feed — and figure in an approximate mortality rate — in order to calculate what it’ll take to get them to reach 10-inches of length by May of 2013.”
Watching the thousands of fast-moving trout swimming around in their tanks and raceways (all of which are cleaned either daily or every-other-day), it was hard to imagine all the mathematical calculations, lab work, feed, vehicle and fuel costs, and man hours that went into raising and maintaining them all. It’s something that fishing enthusiasts might want to think about next time they drop a line into the water. ❖