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(~ ~ 00 ''''1 ,,~) t:') though only a small portion of river was likely sampled, these collections show that Colorado pikeminnow existed in the river from its mouth up to the present-day Navajo Reservoir Basin. Razorback sucker was not found in any of these collections. During the mid-1900s, C. L. Hubbs and R. R. Miller, two noted ichthyologists from the University of Michigan, sampled throughout the West, usually stopping at bridge crossings and sampling with seines for I or 2 days at each site. Some of these collections were noted in various reports, but others were not docmnented and required reviewing collections at the University of Michigan's Musemn of Zoology to find them. Miller collected young Colorado pikeminnow near Mexican Hat, Utah (Figure 2.1), in August 1960 (Sigler and Miller 1963). More recently, musemn specimens from the University of Michigan Musemn of Zoology provided information on more collections between 1934 and 1961 (S. Platania, University of New Mexico, personal communication). c.L. Hubbs collected 44 roundtail chub from the San Juan River near , Shiprock, New Mexico, during two days in October 1944, and three roundtail chub were collected at Mexican Hat, Utah, in 1951. The collections by Hubbs and Miller are important for understanding the native fish abundance in the San Juan River. They were some of the first seine collections, and they were made by ichthyologists interested in the distribution and abundance of native fishes of the West. These collections verified that Colorado pikeminnow reproduced in the San Juan River, and they also verified that roundtail chub was common in the San Juan River, perhaps as far downstream as Shiprock, New Mexico. These collections, along with Jordan's earlier accounts and the scattered collection of adult Colorado pikeminnow, show that Colorado pikeminnow was common in the San Juan River and that roundtail chub was common at least in the river upstream from Shiprock, New Mexico, in the mid-1900s. The absence of razorback sucker in these scattered collections may mean that this species was relatively uncommon in the San Juan River, but it also may mean that this species used areas that were not readily accessible. Typically, razorback sucker adults are only collected during spring, when they often use flooded mouths of tributaries and other low-velocity habitats (Holden and Stalnaker 1975). During other times of the year, razorback sucker appears to use main channels (fyus 1987), which were likely poorly sampled in the early to mid 1900s. Koster (1960) provides anecdotal accounts of razorback sucker in the San Juan River from the mid-1900s, suggesting the species was still found in the river. Sampling of the San Juan River increased in the early 1960s as planning studies for Navajo Dam progressed. In addition, a poisoning operation was conducted just prior to the closure of Navajo Dam to rid the new reservoir basin of native and nOlmative nongame fish. Olson (1962) of the NMGF conducted a pre-poisoning survey of the reservoir area in 1961 and collected both roundtail chub and Colorado pikeminnow. Olson (1962) also conducted spot surveys of fish killed by the poisoning operation. Fish were apparently killed below Fannington, further downstream than had been planned by the poisoning operation, and a few dead Colorado pikeminnow were found. Throughout the 1960s, the NMGF continued fishery sampling in the newly formed Navajo Reservoir, where roundtail chub were very abundant for several years after impoundment. It was not until the late I 970s that relatively extensive surveys of the San Juan River were initiated. Sublette (1977) sampled the river and some of its tributaries from near Pagosa Springs, Colorado, September 2000 2.3 Program Evaluation Report