Garrison Dam National Fish Hatchery
Mountain-Prairie Region
Garrison Dam Frequently Asked Questions: (Photos clockwise from left) Juvenile pallid sturgeon, Bubot fry, Northern pike eggs
Why was the hatchery built? What are the survival rates for pallid sturgeon?
Why was Garrison Dam built? What sort of visitor opportunities are there at the hatchery?
What are the nation's two largest reservoirs? What are burbot?
When did the hatchery get built? What is spawning?
What impacts did dam construction have on the fish communities? What can you tell me about Chinook salmon?
What fish live in these reservoirs? What is imprinting in salmon?
When did the hatchery begin its work with endangered pallid sturgeon? What aren't the hatchery ponds full of water year around?
Can you explain the pallid sturgeon propagation program? Are there fish at the hatchery all year long?
How many pallid sturgeon have you raised and released?  

Why was the hatchery built?
As you can tell by the hatchery’s name, the original intent of the Garrison Dam National Fish Hatchery was to provide fish to offset, or mitigate, the impacts to the fish community resulting from the construction of the Garrison Dam.

Why was Garrison Dam built?
Garrison Dam is a federally funded hydroelectric dam built on the Missouri River in North Dakota by the U.S. Army Corps of Engineers to control flooding and produce energy.  Garrison Dam was completed in 1954 and is the largest in a series of six dams built on the Missouri River as part of the Pick–Sloan Plan and the fourth largest man-made reservoir in the United States. In fact, three of the Pick-Sloan reservoirs on the Missouri River rate in the top five largest reservoirs in the Unites States (Lake Oahe, Lake Sakakawea, and Fort Peck Reservoir). 

What are the nation’s two largest reservoirs?
Lake Mead followed by Lake Powell - both on the Colorado River.

When did the hatchery get built? 
Construction began on the Garrison Dam NFH in 1961 and the first fish produced; northern pike, walleye and rainbow trout, were stocked in Garrison Reservoir in 1962. As the Garrison Reservoir (later renamed Lake Sakakawea) filled, major changes in the Missouri River were realized. 

What impacts did dam construction have on the fish communities?
The Missouri River had a nickname, the Big Muddy. This river historically transported tons of fine sediments from the watershed downstream especially during spring flooding.  Now with the series of reservoirs in place, these sediments have dropped out, flooding is a thing of the past and the river runs colder and clear. These changes have had a dramatic effect on where native fish species could live if they were to survive. Most native species are now restricted to areas of the river in between reservoirs. Twenty years later we are still encountering the consequences of dam building on the Muddy Missouri as we began to identify threatened and endangered species. On September 6, 1990 the pallid sturgeon, a Missouri River native, was listed as an endangered species.

What fish live in the reservoirs?
Cold water held in these deep reservoirs and their downstream tailwaters provided an opportunity for introducing non-native species such as trout and salmon. These species are stocked annually in the reservoir and tailwaters.  Other native species like paddlefish actually thrive in the reservoir but their ability to successfully spawn has been impacted since spawning success is tied to annual flooding. As a result we occasionally stock this species.  Still other native fish like the northern pike and walleye need flooded vegetation or cobble to spawn successfully. Often their spawning success is ruined by water level changes in the reservoir managed to prevent downstream flooding. The lower reaches of the reservoir are often to cold for spawning of native species to occur successfully as well.

When did the hatchery begin its work with the endangered pallid sturgeon? 
Pallid sturgeon propagation was first attempted at Garrison in 1996. That year six days were spent in search of brood fish at the confluence of the Missouri and Yellowstone Rivers and five fish were caught – 4 males and a female. Female sturgeon have a two year reproductive cycle and this female was a year away from spawning, so no luck. The following year we captured a mature female – she was spawned at the hatchery but the eggs didn’t survive. It wasn’t until 1998 that we were first successful at spawning and propagating pallid sturgeon. 

Can you explain the pallid sturgeon propagation program?
Working with sturgeon is not like any of the many other species we raise here. The early years were associated with a steep learning curve. As mentioned earlier, sturgeons do not spawn every year. They also do not exhibit sexual dimorphism – you can’t tell between the sexes unless you use ultrasound or a biopsy technique. Getting wild captured pallid sturgeon to spawn in a hatchery is also difficult. We rely on hormone therapy to initiate ovulation and spermiation.  If the timing is improper, the released eggs are non-viable and we have lost the opportunity for an endangered species to contribute its genetics to the recovery of the species. So we monitor egg development over time by collecting egg samples with a catheter or biopsy. The position of the nucleus in the egg is monitored to determine the correct time for hormone injections. Stress can have a tremendous impact on the response and we are not always successful. Males undergo a similar hormonally induced spawning process but with males we have an advantage. Males are able to spawn annually and through research, cryopreservation techniques have been developed to successfully freeze milt where it can be stored for years at -321 degrees Fahrenheit. Genetics considerations are of course critical in the recovery of any species. The DNA from every adult broodstock is evaluated using small fin clips to insure our mating strategy is appropriate. The analysis also provides the opportunity to select for fish that may have unique alleles that could possibly enable them to adapt better to the changed river.

How many pallid sturgeon have you raised and released? 
Since 1998 this hatchery has released over 275,000 pallid sturgeon fingerlings (3-13 inches in length) and 800,000 larval sturgeons in the Missouri and Yellowstone Rivers from Montana to Missouri. Many other fingerlings and eggs from this facility have been transferred to other hatcheries for further growth and stocking. 

What are the survival rates for pallid sturgeon? 
That’s a work in progress. Based on the current models, survival rates for first year sturgeon range from 5 to 31 percent. Size at release, season, and location of course impact survival.  By the time these fish are six years old, survival is thought to be 95 percent or better. Based on current population models, biologists suggest that hatchery stockings have been successful in preventing extinction of this species. Today there may be more juvenile pallids in the Missouri River of Montana and the Dakotas then there ever was. With changes in river flows, warm water releases from the reservoirs and construction of fish bypass structures, this fish may be able to successfully spawn again without hatchery intervention.

What sorts of visitor opportunities are there at the hatchery? 
Lots. We have a very diverse fish propagation program with multiple species. Some are spring spawners – pike, walleye, pallids, and paddlefish.  Some fall – Chinook salmon. Some in the dead of winter – burbot. So there is a constant change of events at the hatchery.  We are open year around and welcome visitors. Large aquariums are located in the visitor center to observe native fish in 400 gallon aquariums. A hiking trail provides a great opportunity to see the out-of-doors. The trails follow a creek and wetlands area and loop back through a cottonwood forest along the Missouri River. 

What are burbot?
Burbot are known by many names including ling, lawyer, eel pout and cod. Burbot are the only freshwater member of the cod family found in North America. Burbot have a holarctic distribution meaning they are found in the Earth’s northern hemisphere both in North America and Europe. Burbot appear scaleless like a catfish, exhibit a green, yellow and brown mottled color and have a single barbel on the chin. Its delicious flavor makes up for its less than desirable reputation of being eel-like and offers another nickname – the poor man’s lobster.

What is spawning?
Spawning is the term used to describe the reproductive process in the life of a fish where eggs are released, fertilized, develop and hatch. The process at the Hatchery attempts to mimic that in the wild, however under controlled hatchery conditions the survival rates are dramatically improved – in most cases well over 90%. Spawning at the hatchery occurs during specific times of the year, depending on the life cycle of that particular species.

What can you tell me about Chinook salmon?
Chinook salmon were first stocked in Lake Sakakawea in 1976 to fill a void that existed in the deep coldwater areas of the reservoir that was essentially uninhabited by game fish. The stockings were successful and soon after the Chinook salmon fisheries were established in Montana’s Fort Peck Reservoir and South Dakota’s Lake Oahe as well. Chinook salmon are native to the west coast and are an anadromous fish – they spend the early part of their life in fresh water and migrate to the Pacific Ocean to growth and mature, then return to freshwater where the spawn and subsequently die. Young salmon called ‘smolts’ imprint to the water where they incubated as eggs. In the Missouri River Reservoirs they are unable to complete the ocean migration phase of their life and as a result don’t grow to the size found in their west coast cousins.

What is imprinting in salmon?
Imprinting is the process whereby juvenile salmon instinctively memorize the smell or water chemistry of its natal stream – the stream in which they hatched. As they grow into the smolt stage they migrate downstream imprinting along the way. They reach the ocean and journey thousands of miles for four or five years until they mature and are ready to spawn. The adult salmon then journey back to their natal stream relying on their imprinting cues. In North Dakota all the Chinook salmon are hatched at the Garrison Dam National Fish Hatchery. The salmon released in the Missouri River downstream of the dam mature in South Dakota’s Lake Oahe and migrate back to the hatchery where they are guided by their imprinting instincts.  It’s awesome to watch these fish each October fighting their way up the tiny creek leading to the hatchery. Fish collected from this creek are spawned in the hatchery completing the cycle of life for this fish.

Why aren’t the hatchery ponds full of water year around?
The hatchery’s 100 acres of ponds are used for production of several native fish species including pike, walleye, burbot, sauger, perch and paddlefish. Most of these species spawn in the spring of the year and consequently the ponds are filled at that time. The biologists add nutrients to the ponds to encourage growth of plankton, the microscopic plants and animals that feed the young fish called fry. The fry grow quickly in the ponds and in about a month are ready to be stocked into area fishing lakes where natural spawning conditions are lacking.  For many predatory species like pike and burbot, longer stays in the hatchery ponds result in poor survival since after about a month, the fish’s diet shifts from plankton and invertebrates to other fish.

Are there fish at the hatchery all year long?
Trout, salmon, and sturgeon are at the Hatchery in tanks for about a year where they are supplied with a constant flow of well-oxygenated water and fed a diet made specifically for their growth. The following spring, sturgeon, trout and juvenile salmon, or smolts, are released in North Dakota’s lakes and the Missouri River. The trout provide an ‘instant fishery’ as they are released at ten inches and are ready for the frying pan. Many of these fish are released near urban areas to provide opportunities close to home for kids and adults alike to enjoy.  

Last updated: January 13, 2012

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