A study of the river redhorse, Moxostoma carinatum (Pisces; Catostomidae), in the tributaries of the Ottawa River, near Canada's National Capital and in a tributary of Lake Ontario, the Grand River, near Cayuga, Ontario.

Abstract

This study provides baseline data on the River Redhorse (Moxostoma carinatum; Moxostomatini: Catostomidae) in Canada. Sampling focussed on the Mississippi and Gatineau Rivers, in the National Capital Region, in 1998 and 1999. Spawning occurred in rocky, shallow (<2m) fast-water sections in May and June when the temperature reached 17°C. In the Mississippi River, post-spawn specimens were captured on a variety of substrates in deeper waters. Both opercular bones and scales (n = 19) recorded accurate age until age XII after which only the opercular bone provided clear annuli. Growth for both sexes was defined by the following equation: total length at age (mm) = 0.0905 (age)3 - 5.1452 (age)2 + 95.94 (age) + 0.367. Population sizes were assessed through capture-recapture methods. The population size in the Mississippi River was estimated at 622 (+/-6.3 s.d.). The spawning population of the Gatineau River was estimated at 1216 (+/-915 s.d.). It is suggested that the species remains a species of "special concern" in Canada.