Summer 2024 was a continuation of a study started the previous summer investigating the effect of anthropogenic sound on bluegill sunfish (Lepomis macrochirus). This work is a joint study between the College of Saint Benedict + Saint John's University and the University of St. Thomas that was funded by the FDRC. 

Honolulu American Fisheries Society Meeting

Dayna Wiley, an undergraduate Biology major at the College of Saint Benedict conducted the foraging trials to investigate whether sound exposure from simulated intermittent boat traffic affects the foraging behavior of bluegill. 

Bluegill in forage tank with speaker

Dr. Vetter (UST) setting up sound equip.

Anthropogenic noise, such as motorboat traffic, can have adverse effects on fish populations. High-amplitude noise has been shown to cause hearing damage and interfere with essential behaviors, including feeding, migration, and reproduction. Studies suggest that fish regularly exposed to boat noise exhibit different behavioral responses compared to populations in quieter, protected environments. We collected bluegill sunfish from a lake with no motor use (Quiet Lake; Lake Sagatagan, Collegeville, MN) and examined their foraging behavior in response to playback of motorboat traffic (0.06-10 kHz; 150 dB re 1 µPa). This behavior was compared to bluegill from a lake with motor use allowed (Loud Lake; Upper Spunk Lake, Avon, MN). 

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Dayna collecting bluegill

Our results suggest that sounds of certain frequencies (0.06-10 kHz ) or at/below  certain intensities (150 dB) do not significantly alter bluegill foraging behavior. Importantly these findings are likely not applicable to all MN species. 

Minnow consumption differed significantly between Day 1 and Day 2, suggesting a temporal effect on foraging behavior where bluegill satiate during the first 24 hours when prey is abundantly available.

In the summer of 2022, students Nick Franta and Sara Gartner examined how light intensity affects behavior of Deepwater Sculpin (Myoxocephalus thompsonii), a benthic fish common to Lake Superior. The undergraduate researchers determined the as light intensity decreases, sculpin activity increases. It is likely that sculpin increase activity with darkness since the predatory lake trout (Salvelinus namaycush) is usually moves to shallower water at night (diel vertical migration). 

Midwest Fish & Wildlife Conference in Kansas

Their study was the control portion of a larger study investigating sculpin behavior in the presence of the siscowet lake trout. Tom Hrabik (UMD) and Owen Gorman (USGS) are coauthors on this paper which is currently in internal review with USGS. 

The sculpin foraging tank at CSB/SJ

Preparing for fish transport from Lake Superior