Missouri-Yellowstone Adopt-A-Fish

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Missouri River
habitat and biology

The evening light showcases the rugged beauty of the Missouri River near Culbertson.

Each fish species has its place
There are about 240 miles of free-flowing Missouri River between Fort Peck Dam in Eastern Montana and the headwaters of North Dakota's Lake Sakakawea, the next large reservoir downstream from Fort Peck.

Before the construction of Fort Peck Dam in the 1930's, this reach of the Missouri was a much different river than it is today. At that time, the Missouri, like other large rivers, was very dynamic - it changed a lot from time to time. Big flow changes took place in different seasons and created many different types of fish habitat, ranging from deep pools to flooded shallow backwaters.

High flows in the spring and early summer cut and eroded new channels, and areas with sand bars and islands developed downstream where the eroded material was deposited. Thus, the Missouri was constantly changing and creating new habitats.

The native fish that call the lower Missouri River home were well adapted to these varied environments, including times when the waters were very warm and muddy.

The closing of Fort Peck Dam on June 24, 1937 led to a clean, reliable source of electricity for a West that was growing. Also, harnessing the river's flow provided downstream flood control protection. Finally, it created Fort Peck Lake, a huge reservoir with opportunities for boating, swimming, fishing and other recreation. All these were good things.

But the closing of the dam also did other things. It changed fish habitat and the river in the river below the dam. The big flows of spring and early summer weren't so big anymore. Sandbars and island complexes eventually disappeared in areas near the dam, as the new flows did not cut new channels like the bigger, old flows did. The river's water was much colder now than it used to be, because water drawn from the reservoir to generate electricity is released from deep in Fort Peck Lake. This water is also very clear, so the 'Big Muddy' below Fort Peck Dam is much more like a mountain stream than a prairie river.

A shortnose gar is a native
of the Missouri.

Another native species
is the longnose sucker.

All these changes have changed the river for the fish species you'll find there today. For example, rainbow and brown trout do quite well and provide a popular fishery in the first few miles of river below the dam now. Most of the fish species which were native to this reach of the Missouri are still found there today, but are probably fewer in number than they used to be.

You can get an idea of how the river is changed by looking at the native species in the river. In general, you'll find more of these species and great numbers of them the further downriver you go. By then, water temperatures go up and the water is colored more - conditions closer to what it was before Fort Peck Dam was closed.

Several of these native fish species have been designated as Species of Special Concern in Montana, including the blue sucker, paddlefish, sauger, sicklefin chub, and sturgeon chub. The pallid sturgeon is a Federally listed endangered species occasionally found in this reach of the Missouri.

As in most places in the fish world, the diversity of species found in this reach of river is related to the diversity of habitats available. Generally, sandbar and island complexes provide the greatest habitat for native fishes. Shovelnose sturgeon are usually found in the faster-flow areas near sandbar complexes. With their flatter bodies, they are well suited to lie on the bottom in heavy currents. Most of the chubs, including sicklefin, sturgeon, and flathead, have a similar build and also use faster-flow habitats.

Other species, including most of the suckers (river carpsucker, white sucker, smallmouth buffalo and bigmouth buffalo) are usually found in areas with slower flows, like side channels and backwaters. A few of the other suckers (blue sucker, longnose sucker, and shorthead redhorse), however, prefer areas with more current like the main channel of the river.

Most minnows are found in shallower areas with less current. Backwaters and side channels are important nursery areas for nearly all the young fish produced in the river. Young fish prefer these areas because they're usually much warmer and provide lots of food for growing fish to feed one. Of course, predator fish, including northern pike, sauger, walleye, burbot, and channel catfish key in on these nursery areas to feed on these young fish.

This stretch of the Missouri also has some very deep holes in the river, some more than 30 feet deep. Pallid sturgeon like to use these deeper holes, along with paddlefish, burbot, catfish, sauger, and most other species from time to time. Goldeye are one of those amazing species that can be found anywhere in the river, from riffle areas to calm backwaters. They're not too choosy in their choice of habitat.

The Missouri River near the mouth of the Milk River,
an important tributary for spawning.

By looking at some of these fish you can see how they've adapted to what was once the "Big Muddy." Pallid sturgeon, shovelnose sturgeon, channel catfish and stonecats have tiny eyes that probably don't help them to see all that well in muddy water. But they do have several barbels (or whiskers) on their "chins" that they use for "feeling" their way around in muddy water. Other fish, like the goldeye, bigmouth buffalo and smallmouth buffaloes, freshwater drum, and several of the minnows have rather large eyes for seeing in murky water.

Most fish (both native and introduced) in the Missouri spawn during the spring. Paddlefish and pallid sturgeon stage at the confluence of the Missouri and Yellowstone rivers. Once spring run-off starts and flows greatly increase, these fish move up the Yellowstone to spawn. It is suspected that similar changes in the Missouri's flows once triggered them to migrate up the Missouri River for spawning as well.

Many of the other fish in the Missouri also move great distances to spawn. Biologists see good numbers of shovelnose sturgeon, river carpsuckers, blue suckers, paddlefish, and sauger move into the Milk River during early summer, presumably to spawn. It is suspected that some of these fish migrated there from the lower portions of the Missouri River.

It's interesting to note that even with today's technology, there is still a lot we don't know about many of the fish found in the Missouri. Some fish species just aren't that abundant, and others are difficult to sample because they are so small or they are found in habitats that are difficult to sample.

But hopefully, the research efforts on this great river will help ensure that these native fish species are around for many future generations to enjoy - just like we enjoy them today.

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