Reproductive ecology of the greater redhorse, Moxostoma valenciennesi, was studied in the middle reaches of the Grand River, Ontario from 1995 to 1998. Upstream migration to a weir with two fishways was observed during early spring. Spawning began in late May, when water temperatures were above 13°C, and lasted for up to 14 days, except during 1998 when, spawning began in early May and only lasted 5 days. Spawning occurred in shallow riffle areas comprised of pebble, gravel and cobble. Videographic observations indicated that males usually remained on or near spawning riffles, while females were either attracted by the presence or conspicuous behaviour of males. Rapid bursts of snout and lip vibrations were observed in males for up to 5.7 seconds. Vibrations from one male triggered other males to follow suit. When females were present, male snout vibrations usually preceded spasmodic spawning activity among one or two females and up to seven males. Males rolled over one another and the centrally located female, while dorsal and caudal fins vibrated and broke the water surface for up to 10 seconds. Male fish were observed to consume eggs of conspecifics. The youngest fish observed spawning were a five year old male and six year old female. Fecundity ranged from 32000 to 72000 eggs per female for 7 fish between 558 and 610 mm.
Greater Redhorse (Moxostoma calenciennesi) Ecology
In 1997, we began studying greater redhorse (Moxostoma valenciennesi) spawning habitat, spawning behaviour, fecundity, egg and larval development, as well as post-spawn movements and habitat use. We continued this work into 2006 with a 6-year radiotracking and underwater videography study of redhorse in the Grand River.
Cooke, S.J. and C.M. Bunt. 1999. Spawning and reproductive biology of greater redhorse (Moxostoma valenciennesi), in the Grand River, Ontario. Canadian Field-Naturalist. 113: 497-502.
Bunt, C.M. and S.J. Cooke. 2001. Greater redhorse (Moxostoma valenciennesi) post-spawn movements and habitat use. Ecology of Freshwater Fish.10: 57-60.
A combination of radio telemetry and surface observations were used to characterize the movements and habitats of greater redhorse, Moxostoma valenciennesi, after spawning in the Grand River, Ontario, Canada. This river supports a large population of greater redhorse that migrate upstream in the spring to spawn on riffles. After spawning, greater redhorse moved as far as 15.2 km downstream of spawning areas, and maintained summer home ranges in low velocity runs. Mean (± SE) water depth used by greater redhorse was 46.3 ± 0.9 cm and water velocities were less than 5 cm/s. Greater redhorse were usually located over cobble/gravel substrates that were covered with Cladophora. Although interspecific associations with golden redhorse, M. erythrurum, common carp, Cyprinus carpio, smallmouth bass, Micropterus dolomieu, and northern hog sucker, Hypentelium nigricans, were observed, most greater redhorse associated with conspecifics. Areas and habitat types used throughout the summer did not change, until relocation to overwintering areas occurred in early autumn.
Bunt, C.M. and S.J. Cooke. 2004. Ontogeny of larval greater redhorse (Moxostoma valenciennesi). American Midland Naturalist. 151:93-100.
Adult greater redhorse Moxostoma valenciennesi, were seined from the Grand River, Ontario, and artificially spawned in May 1997 and May 1998. Eggs hatched after 6-8 d at a mean temperature of 19 C. Eggs and larval development of 9-22-mm specimens are,described. Ontogeny of larval greater redhorse was compared to that of other syntopic Moxostoma species from previously published studies, including river redhorse (M. carinatum), black redhorse (M. duquesnei), golden redhorse (M. erythrurum), shorthead redhorse (M. macrolepidotum), copper redhorse (M. hubbsi) and spotted sucker (Minytrema melanops). There was significant overlap between most meristic variables that were compared. However, the majority of greater redhorse (up to 18-mm) have myomere counts (27-33 pre-anal myomeres, 9-10 postanal myomeres and 39-42 total myomeres) that are different from other sympatric redhorse species and spotted suckers and may allow identification of greater redhorse as small as 9-mm.