Midwest Fish & Wildlife Conference 2016

AUTHORS: Emily Dean*, Grand Valley State University; Mark Luttenton, Grand Valley State University

ABSTRACT: Native and introduced adfluvial fishes constitute a significant component of Great Lakes fisheries. Seasonal movement of adfluvial fish into coastal streams may deliver substantial amounts of energy that supplement coastal stream production. For example, Conte and Luttenton (unpublished data) noted that 40% of brown trout would consume large numbers of larval suckers when larval suckers were available in the drift while 60% continued consuming invertebrates (e.g., caddisflies). Using bomb calorimetry (cal/g dry weight), we determined the energy density of Chinook salmon muscle and eggs, larval white sucker, steelhead eggs and adult aquatic insects (i.e. caddisfly and mayfly). Energy density of Chinook salmon male muscle, female muscle and eggs yielded 5,062 cal/g, 4,759 cal/g, and 6,209 cal/g respectively. Steelhead eggs were similar to Chinook eggs generating 6,211 cal/g. Larval white sucker energy content (5,726 cal/g) was significantly lower than adult caddisflies (6,743 cal/g) which were energetically similar to salmon and steelhead eggs. Adult mayflies Hexagenia limbata yielded 5,122 cal/g. The high energy content and large runs of introduced adfluvial salmon, steelhead and native white suckers have the potential to seasonally supplement the energy content of coastal streams; this can provide a valuable food source to resident fish and stimulate secondary production.