Contributions of Mayflies (EPHEMEROPTERA

Description

Walleye (Sander vitreus) are an ecologically and economically significant fish harvestedby recreational and commercial fisheries across Ontario. Adult Walleye are piscivores, but
anecdotal evidence from anglers suggests that Walleye often target aquatic insects such as
mayfly larvae (Ephemeroptera). My research examined the diet of Walleye caught from May to
September in Lake St. Joseph in northern Ontario. I examined the stomach contents of angle
harvested Walleye to identify the prey over two summers. Through morphological analysis of
stomach contents, mayflies were found to be a significant prey source for Walleye, during larval
emergence events in early summer, and to a lesser extent throughout the rest of the summer
season. These findings are important for long term management of Walleye populations and
associated resources. I also assess the potential and problems of Walleye management and
research from my experiences of having worked with industry, government, and university
partners on this project.
Author Keywords: alternative prey, Food web interactions, invertebrate, piscivore, Predator prey interactions