Age, growth, and food habits of catostomidae in pool 8 of the Upper Mississippi River

Age, growth, and food habits of ten catostomids from Pool 8 of of the Upper Mississippi River were determined. The catostomids studied were the bigmouth buffalo (Ictiobus cyprinellus Valenciennes), small-mouth buffalo (Ictiobus bubalus Rafinesque), river carpsucker (Carpiodes velifer Rafinesque), quillback carpsucker (Carpiodes syprinus Lesueuer), spotted sucker (Minytrema melanops Rafinesque), Shorthead redhorse (Moxostoma macrolepidotum Lesueur), silver redhorse (Moxostoma anisurum Rafinesque), golden redhorse (Moxostoma erythrurum Rafinesque), and white sucker (Catostomus commersoni Lacepede). Thirty-eight ecotypes were investigated from June through August, 1975. Catostomids were collected from the main channel and backwater areas by use of gillnets, hoopnets, frame nets, seine nets and a boomhocker. Four species (spotted sucker, shorthead, silver and golden redhorse) comprised 94.2% of the catostomids collected from Pool 8. The shorthead redhorse was the most abundant catostomid collected. The shorthead redhorse consisted of eight age groups (0-VII). The period of greatest growth occurred during their second year when they increased their size by 106.4 mm. The most important food item was Tendipedidae larvae by both number (75.8%) and volume (41.2%). There were 10 age groups of silver redhorse collected (0-IX), of which 60.4% were represented by age groups IV-VI. The greatest increase during the second year of growth (l33.0 mm). The most important food items were Tendipedidae larvae (73.3% by number), and was Sphaeriidae (59.5% by volume). The golden redhorse exhibited seven age groups (0-V and VII), with 68.0% belonging to age groups III and IV. The greatest mean annual increment was 108.4 mm, which occurred. during the third year of growth. Food items of importance for golden redhorse included Tendipedidae larvae, Trichoptera larvae, and Ephemeroptera larvae. The spotted sucker was represented by seven age groups (0-VI), of which 38.5% belonged to the IV age class. The greatest mean annual 1ncrement was 105.1 mm and occurred during the second year of growth. Crustaceans were the principle food consumed (98.5% by volume). The remaining members of the Family Catostomidae comprised 5.8% of the individuals collected. The true relative abundance of these groups was perhaps not determined because of sampling only in selected areas and the use of gear that was selective for movements by fish.