Spawning Season Distribution in Subpopulations of Muskellunge in Georgian Bay, Lake Huron

Abstract

Loss of spawning and nursery habitats has been implicated as a major factor in the widespread decline of Muskellunge Esox masquinongy populations in North America. Although there is limited evidence of spawning site fidelity in Great Lakes populations of Muskellunge, such behavior could result in recruitment failure if individuals return each year to spawning sites that have become degraded. We compared the spawning behaviors of individual Muskellunge across three subpopulations in Georgian Bay, Lake Huron, to address the hypothesis that the use of specific spawning sites and spawning site fidelity are independent of the habitat’s suitability for successful recruitment. The study regions (southeastern, northeastern, and northern Georgian Bay) have experienced different impacts from human development and sustained low water levels. We radio-tagged 49 adult Muskellunge and tracked them for up to 3 years (between 2012 and 2015). Sufficient multiyear data were only acquired for 18 individuals in the southeastern region; among those fish, 16 showed fidelity to at least one activity center over 2–3 years. Male Muskellunge occupied significantly smaller activity centers and shallower depths than females during the spawning season. The locations of adult Muskellunge were in close proximity to current and historic nursery sites that had been identified in each region by other studies, supporting the close spatial linkage between spawning habitat and nursery habitat. This study is the first to confirm spawning site fidelity in Georgian Bay Muskellunge, and our results support the spatial association between spawning and nursery habitats. The repeated use of degraded habitat by spawning adults, as appears to be the case in southeastern Georgian Bay, highlights the need to identify and protect spawning and nursery habitats.

Received October 1, 2015; accepted February 3, 2016 Published online June 23, 2016

Acknowledgments

We thank the members of the Chow-Fraser laboratory and field technicians for their assistance with data collection, and we thank the OMNRF for logistical support. We are grateful to our many hosts, who provided us with accommodations and support: David and Brenda Flower, Glen Willis, Harvey and Lorna Meirke, Jerry Burke, Roy and Diana Schatz, Pitfields General Store, and Queen’s Cove Marina. This project was funded in part by scholarships to J.P.L. (Ontario Graduate Scholarship; and Muskies Canada, Inc.) and to J.D.W. (Natural Science and Engineering Research Council [NSERC] Undergraduate Student Research Assistantship; NSERC Canada Graduate Scholarships–Master’s; and Ontario Graduate Scholarship); a research grant from the Sierra Club Canada Foundation, including the Great Lakes Basin Conservancy (Grant 5-21077); the OMNRF through the Canada–Ontario Agreement (Grant 5-21092); and in partnership with the Georgian Bay Musky Association. We appreciate the comments of two anonymous reviewers, whose input contributed to improving the quality of the manuscript.