Potential Use of Remotely Sensed Data for Indexing Fish Habitat in Lakes and Reservoirs: Faster, Cheaper, Better?

Although quantitative approaches to measuring fish habitat have been widely used for streams since the late 1980s, similar methods for lentic waters have lagged behind.  More recently, field-based habitat approaches have been proposed for lakes and reservoirs across the U.S. and Europe; habitat components include riparian cover, littoral cover, submerged structures, substrate composition, and depth and drawdown characteristics. Two of these protocols were applied to two Iowa reservoirs, Easter Lake and Pleasant Creek Lake, during summer 2015. Data were collected multiple times throughout the summer at Easter Lake to assess sensitivity to seasonal changes and between-sample variability.  A fall drawdown at Easter Lake also allowed for ground-truthing of substrate composition and underwater habitat estimates during winter 2015-2016. Results indicated that field surveys provided varying levels of accuracy and required extra time and staff dedication relative to remote sensing.  Remotely sensed data, such as those collected using hydroacoustics, were able to be collected in a single day for an entire waterbody and yielded complete information on bathymetry, substrate, and vegetation; satellite imagery provided up-to-date riparian and watershed data.  Paired with standardized fish collection data, remote sensing could provide useful fish habitat metrics that are fast, cheap, and accurate.