The Blacknose Shiner
By Doug Backlund
WE WOULD SCARCELY recognize the streams and rivers of eastern and southern South Dakota if we could see them as they were before the land was settled. We would find clear, cool streams with sand and gravel beds, and deep pools with abundant vegetation both in the water and on the rich lands bordering the streams. We would also find abundant blacknose shiners, a minnow species that has almost disappeared from South Dakota's streams and rivers.
The former range of the blacknose shiner (Notropis heterolepis) was southern Canada from Saskatchewan east to Nova Scotia and south to Missouri and Ohio. At the turn of the century, this minnow began to disappear from most of its southern range. Now rare in Missouri, Kansas, Tennessee, Ohio, Nebraska and South Dakota, it is still considered common in most of its northern range.
The blacknose shiner was once common and widespread in eastern and southern South Dakota, thriving in the pristine streams. Historical records from Nebraska show that the species was one of the most abundant fishes in that state. Today, blacknose shiners survive in only a few streams in Nebraska. The species was thought to be gone from South Dakota until two dedicated volunteers located a few in two pristine streams in south-central South Dakota in the summer of 1994.
How could a fish that was once so abundant become so rare? The blacknose shiner requires clean, cool, well-oxygenated streams with abundant aquatic vegetation. This fish species is completely intolerant of turbid water and pollution. As lands surrounding prairie streams were disturbed by settlers, erosion increased the turbidity of streams and rivers. Silt covered the sand and gravel bars, suffocating much of the aquatic invertebrate life that many fish rely on for food. Water temperatures increased as streams became shallower. Aquatic vegetation was destroyed by cattle and introduced fish such as carp. Pollution from feedlots, fertilizers and waste water combined with warmer water temperatures to lower the levels of dissolved oxygen in streams.
These changes created conditions more suitable for bullheads and other fish than for species such as the blacknose shiner. Many fish species disappeared from many streams, but the blacknose shiner seems to be the species most affected by these changes. Any stream that still harbors this species does so because of good watershed management practices, whether by intent or by accident.
Shiners are a group of minnows that usually have metallic silver or gold sides. Minnow species are notorious for being difficult to identify. There are more than 100 species of shiners in North America, but the blacknose shiner is one species that is quite easy to identify with a little experience. A black stripe extends from the tail to the nose, passing through the eye but not extending onto the chin or lips. This black stripe is formed from distinctive crescent-shaped markings on the scale margins. The eyes are large, but the mouth is small, and the upper jaw does not extend to the front of the eye. The back is pale yellow, and the sides are silvery. Breeding males have black fins. Adults range from 1 1/2 to 3 inches in length.
Very little is known about the biology of the blacknose shiner. Spawning occurs in Nebraska in the last week of June. The diet includes small aquatic insects, crustaceans and algae. It is known to be one of the host fish of a freshwater mussel, the cylindrical papershell.
Freshwater mussel host fish are the tools of dispersal of many freshwater mussels, commonly called clams. The clams infect the fish with their larvae, called glochidia. Healthy fish are usually not harmed by this relationship. After the glochidia. mature, they drop off the fish. The young clams can then begin a free living existence. Like the blacknose shiner, the cylindrical papershell is also declining in range and numbers.
Although the blacknose shiner is not in danger of extinction, the species is an important indicator of high water quality and pristine streams. The fact that the blacknose shiner still occurs in some streams in South Dakota indicates that the current land management is maintaining the quality of the streams. The question is, how much support is there to ensure the protection of such places, which are becoming rarer and rarer with each passing year? How many other sensitive plants and animals survive in the streams that still support blacknose shiners?
Currently, the fate of these streams is in the hands of private landowners. To those landowners who take this responsibility seriously, we who cherish those special places owe you a great deal of appreciation.
Update: In 1996 the blacknose shiner was listed as a state endangered species in South Dakota