Northern Prairie Wildlife Research Center
In North Dakota alone, biologists have collected nearly 60 species of fish in the Missouri and Yellowstone rivers, and lakes Sakakawea and Oahe-North Dakota's Missouri River System (ND-MRS). Although there have been numerous attempts to strengthen recreational fisheries over the years by introducing new species such as rainbow smelt and chinook salmon, most fish that inhabit the Missouri River System are native species.
Of the numerous native fish species that can be found within the entire Missouri River System, approximately 20 percent are of special concern due to declining populations. Within ND-MRS there are a handful of such species. These troubled species include pallid sturgeon, sicklefin and sturgeon chubs and blue sucker. These species, along with shovelnose sturgeon and paddlefish (among others) have been categorized as "large-river native fish" and vary in size from a few inches long to more than 100 pounds in weight. In North Dakota, only the paddlefish currently offers a recreational fishery.
Concern for the four species is exemplified by the status of the pallid sturgeon, the only federally-listed endangered fish species in North Dakota. The sturgeon chub, sicklefin chub and blue sucker are classified as candidates for federal listing. This classification indicates that declining population trends may be significant enough to warrant listing, but additional information is needed.
What makes these species of fish unique and why are their populations declining? To answer these questions and to better understand these fish we must examine their habitat requirements.
The Missouri River was once one of the most dynamic rivers in the United States. However, channelization and dam construction, beginning with Ft. Peck Dam in 1937 and ending with Big Bend Dam in 1963 dramatically changed habitat for large-river native fish populations. Before Missouri River development, there were more than 2,300 miles of free-flowing river from Three Forks, Montana, to St. Louis, Missouri.
Downstream from Gavins Point Dam near Yankton, South Dakota, 125 miles of river was lost due to straightening and an additional 734 miles of river became channelized. Due to the creation of six mainstem dams, flows for another 373 miles became regulated (though not channelized), and 755 miles of the original river were lost due to impoundment. This leaves the stretch above Ft. Peck Reservoir, Montana as the only portion of free-flowing Missouri River left. This stretch, however, has also been affected by a number of smaller projects such as the Canyon Ferry Dam.
Channelization and impoundment have eliminated migrational upstream movements of fish, changed the normal flow patterns of the river, altered the sediment load of the Missouri, ceased the periodic inundation of the flood plain, transformed the river configuration and varied summer water temperatures. In addtiton, more than 90 percent of sandbar and wetland habitats have been lost during the past 50 years.
Garrison and Oahe Dams
|Free-flowing river (miles)|
|Regulated river (miles)|
|Impounded river (miles)(at normal operating pool)|
|Free-flowing river (miles)|
|The Missouri River System in North Dakota includes the Missouri and Yellowstone rivers and lakes Sakakawea and Oahe. The table above exhibits the dramatic changes to the aquatic environment that were encountered with impoundment of the Missouri River.|
Can anything be done to "fix" the problem of declining populations? First, it must be understood that there are no quick fixes. The Missouri River System is complex and each individual species of fish has unique characteristics and requirements.
Because of this complexity, some modifications to both the U.S. Army Corps of Engineers (USACE) Master Manual as well as the Annual Operating Plan are currently being considered that may benefit large-river native fish species. These modifications may include making seasonal changes to the USACE release patterns from impoundments to more closely simulate natural flows.
Because of the endangered status of the pallid sturgeon, and as required by the Endangered Species Act, a pallid sturgeon recovery plan is being completed by the U.S. Fish and Wildlife Service. Within this plan are both short and long-term strategies that have been developed in hopes of recovering this species. Some of these strategies include habitat identification, protection and enhancement and propagation.
Not only will the pallids receive additional attention in years to come, but other large-river native fish species will also likely see increased sampling efforts. However, to make effective, positive and long-term change for large-river native fish species will require intensive and cooperative field work between numerous governmental entities.
Because many of these species are difficult to sample, field crews have been experimenting with different gear types. Studies and surveys are now underway throughout much of the Missouri River Basin by numerous states, USFWS, USACE and the Bureau of Reclamation.
For example, in ND-MRS during a five day period last April, fisheries biologists from the USFWS, Montana Fish, Wildlife, and Parks Department and the North Dakota Game and Fish Department independently performed field studies near the confluence of the Missouri and Yellowstone rivers. This area, along with the lower 13 miles of the Yellowstone River, exhibits the best remaining habitat for large-river native fish species in North Dakota.
During those five days, USFWS personnel collected two pallid sturgeon, 10 sturgeon chubs and four sicklefin chubs (among other species) on the Yellowstone River in an effort to document habitat utilization by these species. A MFWPD fisheries crew collected three pallids on the Missouri and placed radio transmitters in their abdominal cavities. These efforts enable biologists to track pallids as they move about the Yellowstone and Missouri rivers and assist in determining what habitat types are being utilized.
North Dakota Game and Fish biologists captured, jaw-tagged and released 300 adult paddlefish in the Missouri River. Subsequent tag returns from paddlefish snaggers in both North Dakota and Montana are helpful in determining movement patterns of the paddlefish. These fish have long been known to reside in Lake Sakakawea but spawn in the Yellowstone River. Questions remain, however, regarding recruitment, exploitation and specific spawning sites.
Although long overdue, those five days in April provided the natural resource community some of the best information ever collected in North Dakota on these large-river native fish species. It has become apparent that the changes observed with the development of the Missouri River haven't all been positive. Though anglers searching for walleye, northern pike, chinook salmon and smallmouth bass have benefitted greatly from the impoundment of the free-flowing Missouri River; other species, specifically the pallid sturgeon, sicklefin and sturgeon chubs, and the blue sucker have been negatively impacted.
Fortunately, within North Dakota, there still is a faint picture of the "way it was" as offered by the unregulated and turbid Yellowstone River. Because of the intrinsic value of large-river native fish species and the extreme importance of the (essentially) unaltered Yellowstone River, the public can expect continuing efforts to enhance the populations of some of North Dakota's rarest fish species in this and possibly other areas for many years to come.