Hydroacoustic Sampling for Lake Volume, How Much Data Is Enough?

Lake volume is an important factor used to estimate various biotic and abiotic parameters influencing a fishery.  A more accurate estimate of lake volume provides a more accurate account of these parameters influencing the fishery.  In this study, we quantified the intensity of hydroacoustic sampling effort required to obtain lake volume estimates within certain levels of precision.  Loon Lake in northeastern Washington State, 445 ha in surface area, was surveyed using standard hydroacoustic techniques to obtain GPS referenced depth readings.  Hydroacoustic data was converted into a Triangulated Irregular Network using Geographic Information Systems to obtain an accurate measure of the actual lake volume.  The hydroacoustic survey was conducted using transects that were stratified approximately 45 m.  The 45 m level of surveying effort was considered to provide the most accurate measure of lake volume, against which, other levels of sampling effort could be compared.  While more sampling effort provides greater precision for estimating lake volume, there is a point at which sampling efforts and precision of lake volume estimates are optimized.