. The Canadian field-naturalist. 112 The Canadian Field-Naturalist Vol. 98. Figure 2. Canadian Distribution of the River Redhorse (Moxostoma carinaium). Courtesy of D. E. McAllister, National Museum of Natural Sciences. not known and males and females are not known to differ in growth rate. Spawning has not been observed in Canadian waters but occurs in large rivers or upper reaches of some large tributaries in the USA. The timing of spawning is at water temperatures of 22- 24° C which are found in the Mississippi River of Ontario in late May or early June. Tuberculate males have been captured
. The Canadian field-naturalist. 112 The Canadian Field-Naturalist Vol. 98. Figure 2. Canadian Distribution of the River Redhorse (Moxostoma carinaium). Courtesy of D. E. McAllister, National Museum of Natural Sciences. not known and males and females are not known to differ in growth rate. Spawning has not been observed in Canadian waters but occurs in large rivers or upper reaches of some large tributaries in the USA. The timing of spawning is at water temperatures of 22- 24° C which are found in the Mississippi River of Ontario in late May or early June. Tuberculate males have been captured in early June in Quebec, but by early July specimens had tuberculate scars (Jenkins 1970). In the USA, spawning occurs over gravel shoals in waters from to 1 meter deep. Males con- structed redds varying in size from to meters in diameter and from 20 to 30 centimeters deep. Males are territorial, but spawning required 2 males and 1 female. The second male would join the first in the redd just prior to spawning and leave during the spawning act, or immediately thereafter. Males tended to spawn with females larger than themselves. Egg numbers were 6078-23085 for fish 45 to 65 cm in total length and were relatively large (3-4 mm diame- ter). They hatched in the gravel in six days at 24° C. River Redhorse feed extensively on benthic orga- nisms by sight and are, therefore, susceptible to an introduced bait either on the bottom or in midwater. Gut contents of 10 Ontario specimens showed that. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Ottawa Field-Naturalists' Club. Ottawa, Ottawa Field-Naturalists' Club
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