The current Grand Rapids Hatchery was established in the 1998.
Why was it established? To raise walleyes and white suckers. Sucker production was eliminated in 2009. Suckers were use as feed in muskie production. Advances in dry diet technology eliminated the need to hatch and rear suckers for muskie production. Dry diet has many advantages over live food. It can be purchased in bulk, stored for longer periods of time, requires little additional maintenance, and can be used with automatic feeders, thus reducing staff time.
The spawning run at Cut Foot Sioux is the largest spawning run in the state and is the primary producer of Mississippi Strain walleye. Workers at the Cutfoot Sioux walleye run typically handle nearly 20,000 adult walleye per year. The run has produced on average over 1,300 quarts of eggs and over 90 million walleye fry annually since 1990.
What is the general technology used for the hatchery? The primary source of water is from a well that is 500 feet deep, and city water is used as a secondary source if the well system fails. Large filters are used to remove mineral impurities from the well water, then the water is heated to the desired temperature and pumped to the hatchery batteries.
Has the technology been modified since establishment? The hatchery has recently been modified to better facilitate OTC fry marking and egg disinfecting. OTC is a chemical that leaves a mark on the otolithes, or ear bones, of walleye that can be identified when the fish are older. Eggs are now treated with iodine to reduce the risk of spreading VHS or other fish diseases.
In general, fish management tools fall into one of four categories:
Lake surveys and research provide the information used to select appropriate management tools.
Minnesota has more walleye, walleye lakes, and walleye anglers than any other state. Each year, anglers harvest about 3.5 million walleye.
The best way to maintain walleye numbers is to protect critical habitats. Shore land zoning and related laws aid fish by controlling development and protecting spawning sites and aquatic plants that fish use for cover.
Stocking is another management tool used. Minnesota’s cool water hatcheries produce 2 - 5 million walleye fingerlings and millions of fry each year. Stocking can provide walleye fishing in lakes that lack spawning habitats but can otherwise support walleye. Stocking is also effective for lakes that have been “rehabilitated” or occasionally winterkill. Like any tool, stocking must be used appropriately. If misused, it will be ineffective or possibly harmful to existing fish populations. Stocked walleye may compete for food with other game fish, particularly largemouth or smallmouth bass.
Stocking a lot of small fish does not guarantee catching a lot of big fish. Fish managers estimate only 4 percent of the annual statewide walleye catch comes from stocked fish. The rest is the result of natural reproduction.
Loss of habitat, pollution, and increasing fishing pressure continue to be the biggest issues in walleye management. Everyone must work to improve water quality, control runoff and waterfront development, and maintain aquatic vegetation. Anglers, in addition, will need to comply with regulations and harvest only what they intend to use, for Minnesota to maintain a quality fishery.
WALLEYE AND SUCKER PRODUCTION
Walleye begin spawning in April as water temperatures approach 45 degrees. Workers collect and combine, the eggs and milt from walleye spawning at the Cutfoot station. Spawning usually lasts one to three weeks. On a typical day, 50 - 500 quarts of eggs are taken, with 115,000 eggs per quart. The fertilized eggs are transported to the hatchery and hatch in about three weeks.
Fry are stocked in area lakes and rearing ponds. Fry stocked in rearing ponds are raised to fingerling stage, then stocked in area lakes in the fall. White sucker fry are used as food in muskie operations.
What types of research help with management decisions for this hatchery? There is a long history of stocking fry from the walleye run back into Cut Foot Sioux and Lake Winnibigoshish. This is often referred to as “put back” stocking. The effectiveness of put back stocking is not clear because Lake Winnibigoshish has excellent natural reproduction. In recent years, we have been stocking OTC marked fry into Winnibigoshish to see if the put back fry are contributing to the health of the walleye fishery. This will help us get an idea of how frequently fry should be stocked and at what amounts. Studies are also being done to see if excess numbers may actually hurt the lake as naturally produced fry are replaced by hatchery fry.
What other factors are involved with management decisions involving this hatchery? We conduct lake surveys and assessments to determine where walleye stocking may benefit a lake and where it is ineffective. These evaluations also help us determine appropriate stocking levels and frequencies. The findings of these evaluations are summarized in lake management plans. These plans are used to create annual stocking proposals which tell us how many fry we need to produce in the hatchery in a given year.
The Cutfoot Sioux walleye run is the largest producer of Mississippi River Strain walleye in Minnesota so statewide coordination is very important in making hatchery decisions. Most of the eggs collected at Cutfoot are sent to other hatcheries for hatching and rearing. This requires a lot of logistical thinking when coordinating how eggs are collected, held, and then shipped. Many of these eggs go to southern and western Minnesota for use in walleye fingerling ponds to produce fall fingerlings. Past fingerling production in the Grand Rapids Area has been very limited because of a lack of adequate ponds. Southern and western Minnesota ponds have been historically been important producers of fingerlings stocked in the Grand Rapids Area.
What types of research or other science activities occur along with the activities in this hatchery? We check and adjusting water temperature, iron levels, water flow, dissolved oxygen, etc., in order to determine the best possible setting for the hatchery. If the walleye fry hatch too soon or too late, they may be weak and not make it in the wild. Some fry are naturally weak or get damaged when they are loaded for stocking or marked with OTC. We are conducting experiments to evaluate how OTC marking and other hatchery techniques affect pre-stocking fry mortality. By identifying factors that cause fry mortality, we hope to produce better estimates of the number of live fry being stocked into our lakes and develop techniques to reduce pre-stocking fry mortality.
How does the data collected and/or research conducted at this hatchery inform/affect fisheries managers and fisheries habitats? Data and research is shared from office to office in order to improve hatching and hatchery methods around the state. Any new ideas that are come up with are tested and results are shared among managers.
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