Muskellunge Spawning Habitat and Reproductive Success

Abstract

Abstract Reproduction of muskellunge Esox masquinongy has failed in many waters that formerly supported self-sustaining populations. Laboratory experiments were conducted to isolate causes of such failures. Differential mortality occurred among lots of muskellunge eggs incubated in jars of unaceated lake water over substrates of sand, gravel, silt, aquatic macrophytes, wood, tree leaves, polyethylene screen, and bare glass. High and rapid early mortality (days 1–2), attributable to low dissolved oxygen (DO) concentrations (0–0.1 mg/liter), occurred among eggs incubated on leaves and macrophytes. After day 3, Saprolegnia sp. fungus was implicated in high egg mortalities in jars with inorganic substrates and moderate DO concentrations (3.8–4.1 mg/liter). Lowest mortality rates occurred on organic substrates (silt and wood) amidst intermediate DO concentrations (0.4–1.7 mg/liter) and limited fungal infestation. Among eight midwestern lakes and reservoirs, measured DO at the substrate-water interface in four ...