Aquaculture and Fisheries Commons^™

Effects Of Moonlight And Daylight On Hydroacoustic Estimates Of Pelagic Fish Abundance, Chris Luecke, Wayne A. Wurtsbaugh

Watershed Sciences Faculty Publications

To determine how moonlight and daylight affect hydroacoustic estimates of fish abundance, we used a dual-beam transducer and echo integration to survey pelagic fish (primarily Bonneville ciscoes Prosopium gemmifer) in Bear Lake, Utah and Idaho. During the new moon, the fish were dispersed (not schooling) below the thermocline, chiefly at the depths of 10–20 m. At full moon, they were dispersed but much closer to the bottom, where they were difficult to detect. Acoustic estimates offish density and biomass during full moons were approximately 50% of values derived during new moons. A diel survey during a new moon indicated that …