Fish Production at National Fish Hatcheries
National fish hatcheries play an important role in managing and restoring America’s fisheries. Hatcheries across the Southeast produce both game and non-game species, which contributes to habitat conservation, endangered species recovery, and provides recreation opportunities to the nation’s anglers.
The majority of national fish hatcheries across the Southeast region do not typically keep adult fish for breeding purposes. Instead, a select few broodstock hatcheries produce and provide disease-free, fertilized fish eggs to federal, state, and tribal hatcheries to support their fishery management efforts. Broodstock hatcheries also provide eggs to research centers, classrooms, and universities. While producing millions of eggs annually these facilities focus on preserving genetic diversity to support healthy populations of fish into the future. A small number of eggs produced in broodstock hatcheries are hatched and reared on site so the facility can continue to produce eggs year in and year out.
Mitigation of Federal Water Development Projects
Federal water development projects, such as Army Corps of Engineers (COE) and Tennessee Valley Authority (TVA) dams provide benefits to people including energy production, recreational opportunities, and flood control. Water releases from the operation of these dams create cold tailwaters, which can have unintended impacts on native fish species and their habitat. Water temperatures of large reservoirs stratify near the dam and forms layers of warm, cool, and cold water.
In summer months, heat from the sun reaches the reservoir and warms the upper layers of the water while deeper water remains much colder. During operations of the dam, the water or tailwater below the dam comes from the deep cold water layers of the reservoir. As a result, the once free flowing warmwater fish habitat that supported native species like crappie and smallmouth bass has been altered to a coldwater habitat that is not as conducive to the native warmwater fish species. Dams are also barriers to the natural migration of native fish moving within streams and rivers and may impair the species’ ability to reproduce. Other impediments caused from water releases are fluctuations in water levels and flow and seasonally may adversely affect the water quality in the tailwater. Here in the Southeast, hatcheries can mitigate for these changes in habitat by producing coldwater gamefish such as rainbow trout that will thrive in the coldwater habitats below COE and TVA dams. Stocking coldwater gamefish provides fishing opportunities below these dams, which create a considerable economic and recreational value for local and regional communities.
Coldwater Fish Culture
The hatchery trout life cycle begins fertilized eggs are shipped from a broodstock hatchery in the fall and winter months. When the eggs arrive at the hatchery they are warmed to the hatchery’s water temperature of 50°-55° F and placed in a disinfecting solution to prevent the transfer of pathogens and contagious disease. Hatchery staff then gently move the eggs into incubation jars until they hatch about ten days later. The tiny fish emerge from their eggs with a sac attached that provides nutrition. At this stage the trout are called sac fry. It takes about 10-14 days until the sac is fully absorbed.
Once the nutritional sac is absorbed the fry begin to receive starter feed frequently throughout the day. It takes about five months for the fry to reach three inches in length at which point they are moved outside into raceways to finish growing. Trout are routinely moved among different raceways to reduce the number of fish in a given raceway to improve growing conditions. Employees measure the size of fish in an effort to keep fish of similar size together. Daily feeding of adult trout is based on their size and the anticipated date when they will be released into the river.
When the trout are large enough for release into local rivers, hatchery personnel crowd the adult trout towards one end of the raceway. A mechanical fish pump loads the trout from the raceway into the tanks of a distribution truck. Once filled the truck sets out for locations based on state’s fish and game agency’s tailwater or trout management plan. Employees from these agencies provide the Service a monthly stocking plan that includes the sites to stock and how often to stock the sites. In warm months stocking normally occurs weekly. During the winter months employees usually stock rivers twice a month.