In the Arkansas River system in Kansas there are marked differences between fish faunas of the western and eastern parts of the state. This can be illustrated by comparison of Spring River in Cherokee County with the Cimarron River in southwestern Kansas. Single collections from Spring River or its tributaries usually contain 25 or more species of fish. Collections from the Cimarron rarely contain more than five or six species. Many of those fishes found in Spring River are characteristic of an Ozarkian fauna, and some are endemic to the Ozark uplands. Fish found in the Cimarron or Arkansas in western Kansas are members of a plains fauna of wide distribution. There is mingling of these two faunal groups across the state, with the number of Ozarkian species diminishing westward, and certain plains species diminishing eastward. A number of species such as Moxostoma duquesnii and Notropis spilopterus are limited, on the basis of present records, to Spring River and its tributaries in Kansas. Others have not been taken west of the Neosho drainage. The Verdigris River provides the next major avenue of westward dispersal followed by Caney River, Grouse Creek, and the Walnut River. West of the Walnut River system Ozarkian species have been almost always absent from collections. The Chikaskia River is somewhat exceptional. Moore and Buck (1953) reported from this river several species that seem more typical of eastern faunal associations. Table 10 indicates the stream system in which the present westernmost records are located for a number of fishes found in the Arkansas River system in Kansas.

Table 10.—Present Westernmost Records of Some Fishes in the Arkansas River Basin in Kansas.

Spring River

Neosho River

Verdigris River

Chikaskia River

The westernmost records for seven species are in the area studied.

1. Lepisosteus platostomus.

2. Carpiodes velifer.

3. Moxostoma carinatum.

4. Minytrema melanops. One specimen taken at station G-10 near the mouth of Crab Creek constitutes the present westernmost record. A specimen has been taken by Cross (C-24-51) in the headwaters of the Walnut River.

5. Notropis boops. The westernmost record is station G-5 on Grouse Creek. This fish has been reported slightly west of this in Oklahoma on Big Beaver Creek in Kay County (number 4776, Oklahoma A & M College Museum of Zoology).

6. Notropis volucellus. Two specimens were taken at station G-8 on Silver Creek.

7. Percina copelandi. The westernmost record is from station G-1, two miles above the mouth of Grouse Creek.

The easternmost occurrences of four species are in the area studied. These species are Hybopsis aestivalis tetranemus (Station A-2), Notropis blennius (Station A-1), Notropis girardi (Station A-2), and Fundulus kansae (Station A-2 and Walnut River). These fish are associated with the Arkansas River proper and its sandy western tributaries. In Oklahoma, these fish are found in the Arkansas River as it proceeds eastward and in the downstream portions of some of its tributaries. These fish show little tendency to ascend the streams of the Flint Hills.