High-resolution bathymetry and backscatter data collected at eighteen spawning reefs in NE Lake Michigan using a Norbit iWBMSh multibeam echosounder, 2021-2023 (UTM Zone 16N, NAD 83, NAVD 88)

Eighteen lakebed areas in northern Lake Michigan known to be used by adult fishes for spawning were surveyed between 2021 and 2023 using a Norbit® iWBMSh multibeam echosounder to support fisheries habitat assessment. More than 3500 kilometers of high resolution multibeam data were collected with 0.05m horizontal and 0.5m vertical positional accuracy, with 100% overlap between survey track-lines. Raw echosounder data were processed into bathymetry and backscatter raster layers gridded at 0.5-m and 1-m horizontal resolutions to allow for comparison of reef extents and support development of additional derived products including slope, aspect, roughness, Topographical Roughness Index (TRI), Topographical Position Index (TPI), Hillshade, and 10 Class geomorphic classification. These high-resolution map products can be used to accurately compare reefs and support additional analyses and geographic targeting of future research and restoration efforts.