FRESHWATER FISHES
E. J. Crossman and E. Holm
INTRODUCTION
The fish fauna of the Mixedwood Plains Ecozone is very diverse considering the total freshwater fish fauna of Canada and the faunas of the total areas of the provinces of Ontario and Québec of which the Canadian portion of this Ecozone is a part. The fishes of the Ecozone represent 25 families and 77 genera. The freshwater fish fauna consists of 161 species, five subspecies, and five special stocks. Of these 171 taxa, 131 (76.6%) are native to the area, and 40 (23.4%) are introduced. In addition, 26 hybrids in 7 families have been identified in the Ecozone (Appendix). The hybrids include naturally occurring forms and those developed in fish culture facilities. Fourteen of the 40 introduced species which have been reported in the area have established self-reproducing populations and the remaining introductions have either failed or we have no evidence that populations are established. Introduced species have appeared in the zone as a result of authorized and unauthorized introductions, and as a result of assisted (e.g. canals and diversions) and unassisted northward movement of species long native to the area to the south of the zone.
The species listed in the Appendix for the Ecozone represent approximately 78 % of the total freshwater fish fauna of Canada, 97 % of that of the total area of Ontario, and 86 % of that of the total freshwater area of Québec. This indicates the high degree of diversity of the Ecozone in relation to that of larger areas. The zone coincides approximately with the lower limit of the Wisconsinan Glaciation. The eradicating effect of the glaciers, the relatively short period of time since glaciation, and lower habitat temperatures are probably the most important factors limiting the biodiversity of fishes in the Ecozone. There are about 950 species of freshwater fishes in North America from the arctic regions of Canada to the Isthmus of Tehuantepic (Briggs 1986). The Fauna of Canada represents approximately 19 % of that, in spite of the vast area and the number of diverse watersheds. The unglaciated area closest to the Ecozone is the State of Ohio. The fish fauna of that state consists of 162 species and 13 subspecies (Trautman 1981).
In the Appendix, information on the various kinds of status for each taxa is provided, as follows:
N- native to the Ecozone.
I- introduced into the Ecozone.
IR- introduced into the Ecozone and self- reproducing
COSEWIC Status - the status designated by the Committee on the Status of Endangered
Wildlife in Canada, RANSDR=Report accepted no status designation required, RAISIFSD=Report
accepted Insufficient Scientific Information for Status Designation. The first implies a satisfactory status and the second usually indicates that the species is
represented by numbers too small to provide a true status. The date in brackets indicates
the year in which the status was assigned.
In the columns titled "Ont" (Ontario) and "Que" (Québec), X indicates that the species is present in the portion of the Ecozone in that province, U indicates that the species occurs in that province only within the Ecozone.
The column headed "ODC", or Ontario Distribution Classification, provides the distributional pattern exhibited by each native species in Ontario, according to Mandrak and Crossman (1992b). That provides a type of species association. The designations are as follows:
E Ont - eastern Ontario and Lake Ontario
S Ont - southern Ontario
SW Ont - southwestern Ontario
Gen - generally throughout Ontario
GL&N - Great Lakes and Nelson River watersheds
Misc - not shared by any other species
The columns headed by the numbers 132 to 135 indicate the forms which occur in each
of the Ecoregions of the Ecozone:
132=St-Laurent Lowlands
133=Frontenac Axis
134=Manitoulin-Lake Simcoe
135=Lake Erie Lowland
Scientific names follow Robins et al. (1991).