. The Canadian field-naturalist. 426 The Canadian Field-Naturalist Vol. 107 Tm^w^^. Figure 3. North American distribution of the Johnny Darter, Etheostoina nigrum, from Bruner(1980). (Mandrak 1990). Its presence in Lake Champlain, the St. Lawrence and Ottawa River drainages sug- gest colonization after the separation of Lake Erie and Lake Ontario by Niagara Falls (12 500 ya) due to its absence from the Lake Erie basin (Underbill 1986; Mandrak 1990). Protection Etheostoma olmstedi receives no specific protec- tion in Canada other than that generally afforded by the habitat sections of the feder
. The Canadian field-naturalist. 426 The Canadian Field-Naturalist Vol. 107 Tm^w^^. Figure 3. North American distribution of the Johnny Darter, Etheostoina nigrum, from Bruner(1980). (Mandrak 1990). Its presence in Lake Champlain, the St. Lawrence and Ottawa River drainages sug- gest colonization after the separation of Lake Erie and Lake Ontario by Niagara Falls (12 500 ya) due to its absence from the Lake Erie basin (Underbill 1986; Mandrak 1990). Protection Etheostoma olmstedi receives no specific protec- tion in Canada other than that generally afforded by the habitat sections of the federal Fisheries Act. The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) suggested assigning a vulnera- ble status designation for Etheostoma olmstedi in Ontario pending a status review (Campbell 1988). Etheostoma olmstedi and its close relative Etheostoma nigrum are not considered to be in jeop- ardy in North America (Miller 1972; Williams et al. 1989). However, the Southern Tessellated Darter, Etheostoma olmstedi maculaticeps, is protected in Florida (Johnson 1987). Population Sizes and Trends The Tessellated Darter is considered to be the most abundant darter in Atlantic Coast streams of the eastern United States (Cole 1967; Cooper 1983). For example, Etheostoma olmstedi averaged 25% of the total larval fish drift from 1978-1982, in the Susquehanna River (Gale and Mohr 1978). Tsai (1972) noted a distinct seasonal population change. Population density rose sharply after arrival of the 0-year class, which gradually replaced I and Il-year fish that died off during summer and fall. When the 0-year class was extremely small, and older year classes also reduced, the entire population almost disappeared in October. Although studies have not been specifically con- ducted to assess populations in Canada, inferences based on collection records indicate no evidence of decline. Population trends are unknown because few specimens of Etheostoma olmstedi were collected and/
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