• Comparitive life histories of some species of redhorse,subgenus moxostoma,genus Moxostoma

      Brown, Barbara A (2012-05-09)
      Three species of Moxostoma(M.anisurum,the silver redhorse;M.Erythrurum,the golden redhorse;M.duquesnei,the black redhorse) were examined in order to characterize them as they occur in Otter and Brouillettes Creeks in Vigo County,Indiana and to qualify differences between them in habitat,food habits and morphology.Low numbers of captures of Moxostoma made habitat evaluation difficult.The three species co-occurred in both creeks.Temporal differences in occurrence of redhorses in the creeks were observed.Redhorses were captured with low frequency before August of both years.Golden redhorses were captured in higher numbers than the other species.Moxostoma duquesnei was the least common.The species exhibited similar food habits.Insect larvae,especially chironomids,were found in the highest volume and frequency in all three species.Copepods were the second most important items of both M.anisurum and M erythururum,while the item second in abundance in M.duquesnei was insect pupae.Age 0 fish varied significantly in % volume insect larvae consumed between M.erythrurum(63.9% vol) and M.duquesnei(79.4% vol) and M.erythrurum and M.anisurum(76.2% vol).Similar results occurred in % volume of copepods eaten(M.erythrurum=21.3% vol;M.duquesnei = 4.6% vol;M.anisurum = 15.8% vol).Detailed morphological data were collected from each species.No differences were seen between the sexes.Age classes were compared by ANOVA and Discriminant Function Analysis.Individuals of silver and black redhorses could be identified to age class 100% of the time.Golden redhorses could be correctly aged only 90% of the time due to difficulty in separating older fish.The shape of the lower lips was the best character for dsicriminating among the three species.Moxostoma anisurum was charcaterized by a very acute angle formed by the meeting of the halves of the lower lips,Moxostoma erythrurum by an obtuse angle of aprroximately 140 degrees,and M.duquesnei by an angle of 180 degrees.Only a single specimen of M.erythrurum was difficult to identify using this character.Other characters used exhibited much overlap among the species.