Lauren Shipman


Developing a Procedure for Using a Fish Finder to Measure the Water Depth of Big Rice Lake to Understand the Reason for a Population Decline of Manoomin (Wild Rice)

Located in the northeast part of MN, Big Rice Lake is very important to the Anishinaabe people because of its abundance of Manoomin. Manoomin, the Ojibwe word for wild rice, is deeply ingrained in the culture and history of the Native peoples who harvest it. Unfortunately, since 2006, the Manoomin population in the lake has declined and never recovered to its original levels. A project collaboration between the inter-tribal agency, the 1854 Treaty Authority, and researchers from the University of Minnesota has been studying why Manoomin populations have declined in Big Rice Lake, as well as a number of other lakes across Minnesota and Wisconsin. Tribal resource managers’ knowledge, recent scientific studies, and preliminary results from this collaboration all show that the cause of the population decline varies, but one of the suspected causes in Big Rice Lake is a fluctuation in water depth, which causes other perennial vegetation to out-compete Manoomin. To study this factor, a Humminbird Helix 7 Fish Finder was acquired to create a bathymetric map of Big Rice Lake. This device produces sonar pulses which can be used to determine the depth of the lake bottom. For this study, a procedure for the fish finder was created from other bathymetric research reports, the fish finder manual, and calibration through field testing. This procedure will then be used on a shallow lake around the Twin Cities and refined for later use on Big Rice Lake.

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