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Decline of Native Prairie Fishes


by
Anthony A. Echelle
Oklahoma State University
Geffery R. Luttrell
Oklahoma State University
Robert D. Larson
New Mexico Department of Game and Fish
Alexander V. Zale
William L. Fisher
David M. Leslie, Jr.
National Biological Service
Several prairie fishes that were once widespread and abundant in riverine ecosystems of the south-central Great Plains have declined markedly in their distributions and abundances. Declines of such species likely reflect degradation of riverine ecosystems, particularly in the Arkansas River basin. At a 1994 interregional meeting, the U.S. Fish and Wildlife Service, representing various regions, considered eight riverine aquatic species in the Arkansas and Missouri river basins as Category 2 species (i.e., more data needed to determine appropriateness of listing as federally endangered or threatened species). Four of the eight species were small prairie fishes, including the Arkansas River shiner (Notropis girardi) and the Arkansas River speckled chub (Macrhybopsis aestivalis tetranemus).
We recently investigated distribution and reproductive status of the Arkansas River shiner and the Arkansas River speckled chub in relation to human alterations of river flows within the Arkansas River basin. Human impacts were identified that are detrimental to the long-term stability of native prairie fish assemblages.
Historical distributions of the Arkansas River shiner and the Arkansas River speckled chub were determined by reviewing collection records from appropriate museums. Current distributions of both species were assessed with intensive seine samples throughout historical ranges in Colorado, Kansas, New Mexico, Oklahoma, and Texas (153 collections at 116 localities for the shiner; 223 collections at 159 localities for the speckled chub). River discharges throughout the year were evaluated relative to the reproductive cycles of the fish.

Arkansas River Shiner
This shiner is endemic to the Arkansas River basin; it was widespread in the basin before 1985, but relative abundances varied widely. In three main tributaries of the Arkansas River (North Canadian River, Cimarron River, and Salt Fork of the Arkansas River), the shiner declined markedly between 1983 and 1985, and no specimens were collected after 1990. Our sampling between 1989 and 1991 indicated that native populations were common only in the South Canadian River in Oklahoma, Texas, and New Mexico. An introduced population (perhaps a result of bait transport) occurs in the Pecos River, New Mexico, southwest of the shiner's normal distribution (Bestgen et al. 1989). Overall, the shiner has been extirpated from about 75% of the river reaches in its historical range (Fig. 1). That, coupled with the speed with which populations became extinct in the mid-1980's, prompted action to list the shiner as threatened.

Fig. 1. Historical occurrences of the Arkansas River shiner from collections before 1989 and current occurrences from 1989 to 1991.

Arkansas River Speckled Chub
Historically, the speckled chub occurred throughout the Arkansas River, including the main tributaries in Arkansas, Colorado, Kansas, New Mexico, Oklahoma, and Texas. Our seining collections between 1991 and 1993, however, resulted in capture of speckled chubs at only 22 of the 159 sites sampled, indicating a marked reduction in distribution (Fig. 2). Only six stream reaches in Kansas, New Mexico, Oklahoma, and Texas support speckled chub. We believe that the species is extirpated from Arkansas and Colorado, the North Canadian and Deep Fork rivers in Oklahoma, the Salt Fork of the Arkansas River and Medicine Lodge River in Kansas, and parts of the South Canadian River. Its population in the Cimarron River in Oklahoma varied from very common in collections before 1950, absent from 1984 to 1991, and rare in 1992 and 1993.

Fig. 2. Historical occurrences of the Arkansas River speckled chub from collections before 1992 and current occurrences from 1992 to 1993.

River Flows and Reproduction
We examined duration curves of river flows from three time periods (before 1950, 1950-69, and 1970-88). Our analyses indicated that May-September river flows at most sampling sites were depressed from 1970 to 1988. Overall, 17 of 21 (81%) significant differences among river flows involved depressed flow levels from May to September.
Reproductive activity of the Arkansas River shiner extends from early May to August. The highest reproductive activity in shiners collected in 1989 occurred in June and was coincident with peak river flows. Reproductive activity in shiners in 1989 decreased as river flows declined throughout the summer. Although we do not have comparable reproductive data for the speckled chub, it is clear that it is as affected by river flows (Bottrell et al. 1964) as the shiner.
Both the shiner and the speckled chub have experienced sizeable losses (ca. 75%) in their historical distributions. Local abundances of the shiner have declined since at least the mid-1960's. The shiner and speckled chub now occur together only in the South Canadian River between two reservoirs in Texas and New Mexico and possibly in the Cimarron River in Oklahoma. Declines of these two species parallel similar declines in other native prairie fishes, such as the plains minnow (Hybognathus placitus; Cross and Moss 1987).
Reproduction in these two species appears dependent on periodic and intensive river flows during spring and summer when buoyant eggs are deposited directly into the current. Eggs drift in the current and hatch in 2-4 days (Moore 1944; Bottrell et al. 1964; Cross et al. 1985). In general, the south-central Great Plains is characterized by low but intense rainfall, high evaporation rates, and periodic drought (Zale et al. 1989). Such conditions likely cause great population changes year-to-year and may even cause local extinctions.
Extensive agricultural activities and resultant demands for irrigation water, coupled with the construction of numerous reservoirs in the Arkansas River basin, have degraded and restricted habitats of the shiner and speckled chub and likely other prairie fishes (Cross and Moss 1987). Successful reproduction or recruitment seems to have been impaired. Impoundments have fragmented once contiguous populations of the shiner and speckled chub to restricted river reaches with suitable habitat, effectively eliminating movements between populations and colonization of vacant habitat. Although altered flow regimes may be the ultimate explanation of the declines of these and other species, the actual pattern of decline differs between species. Overall, these declines indicate that human activities have degraded aquatic prairie ecosystems to the point of endangering parts of endemic fish assemblages.
For further information:
Anthony A. Echelle
Oklahoma State University
Department of Zoology
Stillwater, OK 74078
References
Bestgen, K.R., S.P. Platania, J.E. Brooks, and D.L. Probst. 1989. Dispersal and life history traits of Notropis girardi (Cypriniformes: Cyprinidae) introduced into the Pecos River, New Mexico. American Midland Naturalist 122:228-235.

Bottrell, C.E., R.H. Ingersol, and R.W. Jones. 1964. Notes on the embryology, early development, and behavior of Hybopsis aestivelis tetranemus (Gilbert). Transactions of the American Microscopical Society 83:391-399.

Cross, F.B., and R.E. Moss. 1987. Historic changes in fish communities and aquatic habitats in plains streams of Kansas. Pages 155-165 in W.J. Matthews and D.C. Heins, eds. Community and evolutionary ecology of North American stream fishes. University of Oklahoma Press, Norman.

 Cross, F.B., R.E. Moss, and J.T. Collins. 1985. Assessment of dewatering impacts on stream fisheries in the Arkansas and Cimarron rivers. Final Report, Kansas Fish and Game Commission, Nongame Wildlife Contract 46. 161 pp.

Moore, G.A. 1944. Notes on the early life history of Notropis girardi. Copeia 1944:209-214.

Zale, A.V., D.M. Leslie, Jr., W.L. Fisher, and S.G. Merrifield. 1989. The physicochemistry, flora, and fauna of intermittent prairie streams: a review of the literature. U.S. Fish and Wildlife Service Biological Report 89(5). 44 pp.


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