Black Redhorse Ontogeny

Adult Black Redhorse (Moxostoma duquesnei), were seined from the Grand River, Ontario and artificially spawned in May 2007 and May 2008. Eggs hatched after 9-16 days at a mean temperature of 20° C, and after 11 - 25 days at a mean temperature of 17° C. Eggs did not develop fully at temperatures <11° C. Eggs and development of larvae between 9 and 24 mm (TL), and juveniles up to 35 mm are described. Ontogeny of larval Black Redhorse was compared to that of other Moxostoma and Minytrema species from previously published studies, including Greater Redhorse (Moxostoma valenciennesi), River Redhorse (Moxostoma carinatum), Golden Redhorse (Moxostoma erythrurum,), Shorthead Redhorse (Moxostoma macrolepidotum), Copper Redhorse (Moxostoma hubbsi) and Spotted Sucker (Minytremamelanops). There was significant overlap between most meristic variables that were compared. However, the majority of Black Redhorse (up to 18 mm) have higher myomere counts (34 - 39 pre-anal myomeres, 6 -11 postanal myomeres and 40 - 47 total myomeres) that are different from other redhorse species in Canada, and, in combination with knowledge of congeneric distributions and spawning windows, may allow identification of Black Redhorse as small as 9 mm.