Food of Deepwater Sculpin, Myoxocephalus Thompsoni, from Southeastern Lake Michigan

Abstract

Pontoporeia hoyi was the major food consumed by most sizes of deepwater sculpins ( Myoxocephalus thompsoni) during spring and summer, 1981–82, at a 100-m station in southeastern Lake Michigan. There was no apparent seasonality in choices of food or volumes consumed. Mysis relicta made up less than 9% of the total food volume and averaged second to Pontoporeia volumetrically—a result which differed from previous investigations for Lake Michigan. Reduced consumption of Mysis in our study compared to previous work may be a function of lower prey density or station depth; mysids may have been farther above the lake bottom than at previously studied, more shallow stations. Ostracods were important in 6- and 7-cm fish diets. Mysis, chironomids, and fish eggs were only found in sculpins larger than 8 cm. Chironomid larvae, which typically burrow into sediments, and copepod and cladoceran zooplankton constituted a small percentage of the diet of all sculpins. These results indicated that the deepwater sculpins examined were primarily epibenthic predators at the sediment-water interface and apparently did not burrow for food or feed higher up in the water column.