Lake trout spawning at Julian’s Reef, Lake Michigan. What, the shell?

John Janssen, Jeffrey Stein, Erik Carlson

Research output: Chapter in Book/Report/Conference proceedingConference contribution


The best lake trout spawning reef in Lake Michigan is Julian’s Reef, about 20 km offshore of Illinois, with a summit of about 27 meters. Lake trout eggs were first reported for the site in 1995 via unmanned submersible (ROV) observations. Quagga mussels and round gobies were absent at that time. Currently about 50% of the lake trout spawners are naturally reproduced. Quagga mussels mostly encrust the rocks and there are areas of “bleached” shells presumably concentrated by hydrodynamic events. Via ROV-based suction sampling and electroshocking we found both eggs and alevins to be almost exclusively in bleached quagga shell beds. We also found egg predation by slimy sculpin, round gobies, lake whitefish, and burbot.
Original languageEnglish (US)
Title of host publicationLarge Lakes Research: Connecting People & Ideas
StatePublished - 2019


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