. The Canadian field-naturalist. 1998 Houston: Status of the Western Silvery Minnow 149. Figure 2. North American distribution of the Western Silvery Minnow, Hybognathus argyritis (after Scott and Grossman 1973; Pflieger 1980). afforded, if required, under Alberta provincial wildlife legislation. The species is considered of spe- cial concern in Alberta (Johnson 1987). Population Sizes and Trends The species is known only from from one collec- tion on the South Saskatchewan River and seven sites on the Milk River in southeastern Alberta. The species was first collected in Alberta from the Milk
. The Canadian field-naturalist. 1998 Houston: Status of the Western Silvery Minnow 149. Figure 2. North American distribution of the Western Silvery Minnow, Hybognathus argyritis (after Scott and Grossman 1973; Pflieger 1980). afforded, if required, under Alberta provincial wildlife legislation. The species is considered of spe- cial concern in Alberta (Johnson 1987). Population Sizes and Trends The species is known only from from one collec- tion on the South Saskatchewan River and seven sites on the Milk River in southeastern Alberta. The species was first collected in Alberta from the Milk River in 1961 (UAMZ 5320) and subsequent collec- tions between 1971 and 1976 verified its presence at a further six sites along the Milk River (UAMZ 2846, 3335, 3234, 3241, 3244, , ). The number of specimens collected at each site varied from one to 26 and one site was visited in 1974 (UAMZ ) and again in 1976 (UAMZ ), 26 specimens were taken in 1974 and 2 in 1976, apparently it has not been looked for since. The only known record from the South Saskatchewan River is that reported by Henderson and Peter (1969) and it has not been found there since. Nelson and Paetz (1992) indicate the need for further specimens from the South Saskatchewan River before recognition of its estabhshment there. There is no information available to establish pop- ulation sizes or trends. The species appears to be native to the Alberta fauna and has, no doubt, been there for some time, previously going unnoticed or perhaps misidentified as the Brassy Minnow as it was first described by as Hybognathus argyritis by C. P. Girard in 1856 from specimens collected from the Milk River in Montana (Nelson and Paetz 1992). Willock (1968) hypothesized that the species may have been more abundant in upper reaches of the Milk River prior to 1900. Increase turbidity resulting from channelling of irrigation water into the Milk River in the early 1900s may have caused a decline in the populat
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