. The Canadian field-naturalist. 54 The Canadian Field-Naturalist Vol. 104. 1 0 m m Figure 1. Least Darter, Etheostoma microperca, male (adapted from Burr and Page 1979). tributaries of Lake Ontario, the drainage of Lakes Erie and St. Clair, and the southeast drainage of Lake Huron (Scott and Grossman 1973). These small fish are often not detected in surveys because of their small size and secretive habits (Trautman 1957; Scott and Grossman 1973; Smith 1979). They may occur in some areas completely unknown to investigators until finally being dis- covered through lengthy, repeated sampling (Tr
. The Canadian field-naturalist. 54 The Canadian Field-Naturalist Vol. 104. 1 0 m m Figure 1. Least Darter, Etheostoma microperca, male (adapted from Burr and Page 1979). tributaries of Lake Ontario, the drainage of Lakes Erie and St. Clair, and the southeast drainage of Lake Huron (Scott and Grossman 1973). These small fish are often not detected in surveys because of their small size and secretive habits (Trautman 1957; Scott and Grossman 1973; Smith 1979). They may occur in some areas completely unknown to investigators until finally being dis- covered through lengthy, repeated sampling (Traut- man 1957) or through the use of seines with a smaller than standard mesh size (Scott and Grossman 1973). A keen eye can detect their darting movements in clear water as they dive and swim into the sand. For these reasons, Trautman (1957) assumed that Least Darters probably had a more extensive, but undiscovered, range in the United States prairies before 1900, but is no larger present in the area because of extensive habitat modifications. The same can be true for many Lake Ontario tributaries. The remote Ozark populations may have been, until recently, connected to the northern groups of Etheostoma microperca by an undetected popula- tion or series of populations (Kuehne and Barbour 1983). Pflieger (1971), however, has suggested that the Ozark groups are naturally separated from other populations of the species because of glaciation and geomorphological processes, and that Ozark populations are "glacial ; Protection Least Darters receive legal protection in the state of Iowa, but not in other states though the fish are of special concern in Kansas, Kentucky and Wisconsin (.Johnston 1987). The species receives no specific protection in Canada but is given incidental protection through the fish habitat sections of the Fisheries Act. Population Sizes and Trends No surveys of the Least Darter have taken place, thus populations sizes arc difficult to assess.
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