Remote sensing of capelin and other biological features in the North Pacific using lidar and video technology

Abstract

We evaluated airborne remote sensing, using lidar and colour digital video, in the North Pacific in 2000. Specific objectives were (1) to determine lidar depth-penetration range, (2) to develop ocean colour indices as a proxy for depth penetration and Chl a , (3) to compare lidar with acoustic and net-sampling data, (4) to define diurnal variability over large areas, and (5) to evaluate strengths and weaknesses. Depth penetration ranged from 18 to 50 m in non-silty water, with lowest values observed inshore by day and highest values on the continental shelf at night. A green index, derived from the three-band video data, was significantly related to depth penetration and was in general agreement with SeaWiFS satellite Chl a values. Significant correlations with acoustics data were obtained in an area with a high concentration of capelin, Mallotus villosus (Müller). The day and night distributions of two capelin locations are shown. At a number of zooplankton sampling stations, there was general agreement between densities derived from lidar and vertical net tows. We discuss the spatial patchiness of capelin and zooplankton, ramifications of those distributions on survey design and sampling, strengths, weaknesses, and future research direction for aerial remote sensing.