Movement patterns and habitat characteristics of Lake Sturgeon ( Acipenser fulvescens) in the St. Marys River, Michigan, 2007–2008

Abstract

Historically, the St. Marys River (SMR), Michigan, provided suitable habitat for lake sturgeon ( Acipenser fulvescens) but their population declined dramatically during the past century due to overharvest and habitat alteration. Since 2000, the Lake Superior State University Aquatic Research Lab has monitored a remnant population of lake sturgeon in the SMR. During 2007 and 2008, lake sturgeon were implanted with sonic transponders to determine spatial extent, movement patterns, and habitat use in the SMR. Telemetry observations indicated that lake sturgeon inhabit a 40 km river reach, representing approximately one-third of the total area of the SMR. Lake sturgeon movement in the SMR was confined to an area between the North Channel of Sugar Island to the southern end of East Neebish Island, with the majority centered around the north end of Lake George. Additionally, lake sturgeon were not observed in the main shipping channel which suggests that they may actively avoid areas with high shipping traffic. During this study, individual weekly movement rates of lake sturgeon varied from under 100 m to over 25 km. Lake sturgeon used transition areas between lotic and lentic waters extensively. These areas create depositional habitats that may be essential foraging areas for lake sturgeon in the SMR. Telemetry results to date have not confirmed the spawning location of lake sturgeon within the SMR. However, two females with partially mature eggs were tagged in 2007 and may spawn within the next 2 years. Their movements could lead to the positive identification of the spawning location which would provide essential information for fisheries managers in the SMR.