Fish community size spectra and the role of vessel avoidance in hydroacoustic surveys of boreal lakes and reservoirs

Wheeland, Laura J. (2014) Fish community size spectra and the role of vessel avoidance in hydroacoustic surveys of boreal lakes and reservoirs. Masters thesis, Memorial University of Newfoundland.

[English] PDF (Migrated (PDF/A Conversion) from original format: (application/pdf)) - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. Download (2MB) [English] PDF - Accepted Version Available under License - The author retains copyright ownership and moral rights in this thesis. Neither the thesis nor substantial extracts from it may be printed or otherwise reproduced without the author's permission. (Original Version)

Abstract

Hydroacoustic data were used to quantify vessel avoidance by fishes, and derive fish community size spectra in two shallow boreal systems in eastern Manitoba, Canada. Lac du Bonnet reservoir and adjoining lakes at Nopiming Provincial Park were studied during summer 2011 and 2012. The magnitude of boat avoidance varied between these relatively similar water bodies (p = 0.04), but was not significantly influenced by fish depth or survey speed. Length-frequency spectra were determined from acoustic surveys at Lac du Bonnet, and acoustic data were used to map bathymetry of the reservoir. Community abundance (spectra height) was greater in 2011 then 2012 (p < 0.05), and decreased through the summer. Spatial variation in spectra parameters appear to be related to physical habitat characteristics. I conclude that vessel avoidance should be quantified in situ, and that acoustic size spectra may be used to monitor differences in fish communities over time and among habitats.

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