Hatchery - Fact Sheet Peterson State Fish Hatchery

Peterson Hatchery

  • Year-round, cool water facility
  • Species produced: Lake Trout
  • Year Established: 1880’s as a campground; 1940’s as a private hatchery; and 1988 as a DNR State Fish Hatchery


History - 1880’s to 1980’s: The first recorded development of this site occurred in the 1880’s. Sometime prior to 1886, Addis E. Hazzard (owner of the drug store in Rushford at the time) created a campground here. Improvements over the years included an artificial lake to support trout, clearing brush, and building a “…commodious log-cabin containing a substantial fireplace and other conveniences”. During the late 1800’s, Camp Hazzard was a favorite spot for many area citizens to rest, relax and socialize during the summer months. Several floods hit the campground over the years and it was finally abandoned in 1915 after a “…devastating flood brought it to ruin.”

Before the flood of 1915, the artificial lake was already supporting young trout. After the flood, it is unclear how the site was used. Then, in the 1940's, four men from the area developed fish rearing ponds and created a bait minnow hatchery. The bait minnow endeavor was not successful and the owners switched to trout production. Trout production continued until 1988 under several different managers and owners. The Minnesota DNR purchased the trout farm in August 1988 to supplement DNR’s trout production capabilities.

History - 1988 to present: In late 1988, the new DNR facility was renamed the Peterson State Fish Hatchery and began producing Atlantic salmon, lake trout, and brook trout for stocking in Minnesota waters. Rainbow and brown trout production started at Peterson in 1989. At that time, the hatchery was comprised mostly of dirt bottom ponds that were open to the sun and accessible to predators, the hatchery piping was antiquated and the springs were unprotected. Few of the facilities were suitable for raising lake trout or other species that need darker, more protected conditions. An extensive, multi-phased, renovation began in 1989 and reached completion in 2002. The goals of the renovation were to create facilities that would:

  1. Effectively produce any species and size of trout or salmon.
  2. Rely on gravity flow from the springs rather than on pumps and electricity.
  3. Be relatively simple and inexpensive to operate.

The renovation met all of those goals. During the renovation years, the hatchery maintained full fish production by completing one segment at a time and adapting to the conditions at hand.

The previously uncovered spring ponds are now covered and protected. Well-oxygenated, 48-degree spring water, moves by gravity flow through pipes from the springs to the fish rearing areas. Valves distribute and control the flow. Hatchery workers measure flow rates by using weirs, flumes, flow meters and pressure sensors. Peterson Hatchery uses round fish rearing tanks almost exclusively. Round tanks promote self-cleaning and uniform water quality, leading to better utilization of the space and water by the fish. Buildings or tent-like domes enclose all of the tanks to provide a dark, undisturbed environment for the fish. Fresh water enters each tank through a spray bar at the outside edge, circles around and around, then drains through a flat screen in the floor at the center of the tank. The motion of the water removes nearly all fish waste from the tank. A standpipe outside the tank controls the water depth in the tank. After overflowing the standpipe, the water flows through pipes to special settling tanks that collect the fish waste before it can escape to the trout stream. Periodic pumping of the settling tanks moves the waste to a “composting pond” where it is broken down by vegetation, snails and other organisms.

Peterson uses automatic feeders for most fish feeding. Using feeders enables the fish to remain undisturbed for most of the day and reduces labor. 12-hour belt feeders provide food to the fish over an extended period without the need for electricity. Each belt feeder has a clock mechanism that provides the power. Pulling out the feeder’s belt to full extension winds and starts the clock. Fish food is placed on the belt. As the clock runs, the belt is re-wound and the food falls into the tank. The water current circulating around the tank distributes the food to the fish.

Fish Management

In general, fish management tools fall into one of four categories:

  • protecting and restoring habitats and water quality;
  • regulating the harvest;
  • stocking; and
  • public education.

Lake surveys and research provide the information used to select appropriate management tools.


The hatchery annually produces about 100,000 to 130,000 lake trout for Minnesota's Inland Lake Trout Program. It also produces a few thousand splake, a lake trout/brook trout hybrid, and stocks those into several other inland lakes. Our lake trout are stocked into approximately 26 deep, cold lakes from Grindstone Lake near Hinckley to lakes near Grand Rapids, International Falls, Tower and Grand Marais. Some fish are stocked as 4" fingerlings in October, while the majority are stocked as 8" yearlings in April and May. Peterson Hatchery maintains captive lake trout brood stock to provide eggs for its program.


Minnesota has 112 lake trout lakes concentrated in northeastern Minnesota, but extending as far west as Brainerd and as far south as Hinckley. Lake trout lakes are cold and deep, well oxygenated, of high water quality and are often associated with pristine or wilderness environment.


Incubation of fertilized trout eggs at Peterson begins in Heath incubators. Each incubator stack has 16 trays and each tray in the stack holds about 20,000 fertilized eggs. Peterson’s incubation capacity is 3 million fertilized eggs. It takes nearly 45 days for the lake trout eggs to develop to the “eyed stage”. Once the eggs are eyed, the fish culturists use an electronic “egg sorter” to sort the opaque, white, dead eggs from the translucent live eggs. Live eggs from the egg sorter next go to “cannon” incubators, made of pvc pipe. Upwelling flow in the cannon gently rolls the eggs for about two weeks until they hatch. The water flowing out of the cannon automatically carries eggshells away. About 10 days after hatching the fry are “flow sorted”. Flow sorting separates the strong, healthy fry from dead and crippled fry. Flow sorting uses a trough that is partially covered and has a gentle flow. Healthy fry swim upstream and under the cover while dead and crippled fry remain in the uncovered portion of the trough. The culturist returns the healthy fry to the Heath incubators where they continue to develop. By early January, the fry have grown to about 0.75”, have absorbed their yolk sac, and are ready to start feeding. They are flow sorted once more, then inventoried to floating baskets in the nursery tanks and started on feed. As the fish grow, Peterson’s fish culturists split the population into more and more tanks.

Peterson’s fish culturists use computerized spreadsheets to project feed, growth, space and flow needs for each tank of fish. By using anticipated growth rates, feed conversion rates and other parameters, the fish culturist can determine how much and what size feed to use each day, when to increase flow and when to split the fish to more tanks. The spreadsheet enables the user to look months ahead to adopt the best rearing plan for all of the fish on station. At the end of each month, the fish in every tank are “rated” by weighing and then counting a portion of the fish. The fish culturists determine the actual performance of the fish in each tank by comparing this “end of the month” size to the previous month’s data. If necessary, the culturists adjust the projection spreadsheet to reflect actual performance. Whenever the hatchery workers move fish to new quarters they conduct a full inventory.

Minnesota’s Pollution control Agency regulates the water quality leaving the Peterson Hatchery. A fish culturist collects and submits water samples twice monthly, and produces monthly and annual water quality reports. In addition to submitting water samples, Peterson’s staff measures water flow and dissolved oxygen concentrations several times each month. Peterson provides this information to numerous agencies interested in ground water.

During July and August, all of the young fish are marked so that Fish Managers can identify them. Fish Manangers can learn a great deal from fish recaptured after stocking. To mark the fish a skilled laborer uses a small scissors to remove a designated fin, or combination of fins, from each 3” fish. The fish are counted as they are marked, providing an extremely accurate inventory. Experienced fin clippers clip between 4,000 and 6,000 fish per day.

Fish stocking occurs in April and May for yearlings, and in October for fingerlings. Peterson uses a medium duty truck with three live haul tanks, or an eight-tank tractor-trailer to transfer fish from the hatchery to the stocking sites. Each transport tank provides oxygen and other life support needs for the fish during transport. Most of Peterson’s stocking sites are in Northern Minnesota so stocking trips normally take 12 to 20 hours to complete. Some of the sites are not accessible by road so a DNR floatplane flies the fish to the lake for stocking.

Science Informing Management

What types of research help with management decisions for this hatchery?

  • Genetics research has helped to identify wild lake trout populations that share similar characteristics, enabling the development of hatchery stocks that may meet specific needs.
  • Fish food and nutrition research has developed diets that produce excellent fish survival, growth, feed conversions, and greatly reduced waste production. Many diets are available to meet the specific requirements of the fish.
  • Over 100 years of previous fish culture research has developed general guidelines for all aspects of cold-water fish culture. Peterson’s staff applies these methods, as appropriate, to this hatchery.
  • Because every fish hatchery is a unique, specialized, artificial environment, each hatchery must conduct its own extensive research on site to determine the best methods, techniques, supplies, materials and timing for successfully producing the fish that it rears. The fish culture information collected on a daily basis is actually continuing research that helps refine our knowledge about the fish at this facility.

What other factors are involved with management decisions involving this hatchery?

  • Budget and staffing factors affect almost every management decision.
  • Environmental and energy concerns often shape decisions.
  • Fish diseases and invasive species affect where and how fish are moved and used.

What types of research or other science activities occur along with the activities in this hatchery?

  • Ground water studies.
  • Computerized data management.
  • School environmental tours and stream invertebrate studies.

How does the data collected and/or research conducted at this hatchery inform/affect fisheries managers and fisheries habitats?

  • Peterson’s lake trout, marked with a fin clip, enable Fish Managers to evaluate survival and performance of fish stocked in the lakes.
  • Egg survival information for captive brood stock influenced fish managers to study the development of a different genetic strain of lake trout for stocking inland lakes. This eight-year study is composed of two parts, performance of the fish in the hatchery, and performance in the lakes following stocking. The future direction of the inland lake trout program hinges on the outcome of this study.
  • Peterson’s captive lake trout brood stocks have genetics similar to the fish that Minnesota has been stocking in Lake Superior. Lake Superior lake trout are almost self-sustaining and stocking numbers have been dropping for several years. Having a disease free captive brood that could meet the needs of both inland and Lake Superior gives managers an opportunity to adjust hatchery production to meet other needs.


The Peterson Hatchery is open to visitors from 7 a.m. to 3:30 p.m. weekdays and 7:30 to 10:30 a.m. on weekends. Operations change from season to season, so there is always something new to see.

  • Guided tour: Available for groups by reservation.
  • Self-guided tour: Available most days from April through November.  Winter tours are available by appointment.