**ABSTRACT NOT FOR CITATION WITHOUT AUTHOR PERMISSION. The title, authors, and abstract for this completion report are provided below.  For a copy of the full completion report, please contact the author via e-mail at jaustin@d.umn.edu. Questions? Contact the GLFC via email at frp@glfc.org or via telephone at 734-662-3209.**

 

Reproductive behavior of wild and hatchery lake trout in the Drummond Island Refuge, Lake Huron: Modeling and physical observations component

 

Austin, J. A.1

 

1Large Lakes Observatory

University of Minnesota

Duluth, MN 55812

 

April 2015

 

ABSTRACT:

 

As an addendum to acoustic fishery work performed in the vicinity of Drummond Island, we made observations of physical parameters and configured a numerical model to help to put bio-acoustic observations into a broader context.  Observations consisted of deployments of thermistors during the 2012, 2013, and 2014 field seasons coincident with a subset of the acoustic array, as well as the deployment of an acoustic Doppler current meter (ADCP) at a single site in 2013. The thermistor array provided data on temperature along the lake floor in the vicinity of the deployment. A clear seasonal signal is present, along with indications of lateral motion, undulations of the thermocline, and a weak near-inertial signal in the vicinity of the thermocline. ADCP observations showed activity in three spectral bands: the near –inertial band (~16h) associated with the rotation of the earth, diurnal tides (24h), and the primary Helmholtz mode (~67h), which represents the exchange of water between Lakes Michigan and Huron.

A numerical model was configured to simulate circulation in the vicinity of the study site; the model consisted of a fully but coarsely resolved Lake Huron and Lake Michigan, with much higher resolution in the vicinity of the study area, with spatial resolution on the order of 150m- 200m in this region. The model was run under a number of different wind and river forcing scenarios; implementation of surface heat fluxes (and hence simulation of the formation and breakdown of stratification) was beyond the scope of this study. The model provides a broader spatial view of currents in the vicinity of the study area, and allows us to characterize the influence of meteorological and riverine forcings.