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The Greal Plains — Our Livinc; RfsoKirex 



Fig. 1. Historical occurrences of 

 the Arkansas River sliiner from 

 collections before 1989 and cur- 

 rent occurrences from 19S9 lo 

 1991. 



1985. but relative abundances varied widely. In 

 three main tributaries of the Arkansas River 

 (North Canadian River. Cimanon 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 (per- 

 haps a result of bait transport) ticcurs in the 

 Pecos River. New Mexico, southwest of the 

 shiner's nomial distribution (Bestgen et al. 

 1989). Overall, the shiner has been extirpated 

 from about 75% of the river reaches in its his- 

 torical range (Fig. 1 ). That, coupled with the 

 speed with which populations became extinct in 

 the mid-1980"s. prompted action to list the shin- 

 er as threatened. 



Fig. 2. Historical occurrences of the Arkansas River speckled chub from collections before 1992 

 and current occurrences from 1992 to 1993. 



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 sein- 

 ing collections between 1991 and 1993, howev- 

 er, 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. 



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 collect- 

 ed in 1989 occuiTed 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 affect- 

 ed 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 paral- 

 lel similar declines in other native prairie fishes, 

 such as the plains minnow {Hyhognathus plac- 

 itiis; 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 



