New Optical, Acoustic, and Autonomous System Technologies for Fisheries Research

Traditional ship-based fisheries sampling methods are limited in their ability to collect data on time scales of short-term unpredictable events such as storms or upwelling, and for continuous sampling over longer periods such as monthly lunar and seasonal cycles.  Ship-based fisheries methods also have limitations sampling smaller spatial scales relevant to vertical thin biological layers, and horizontal features associated with internal waves, river and ocean fronts, and near shore alongshore currents.  New methods for fisheries data collection are therefore needed which can extend the range of temporal and spatial scales compared with traditional ship-based sampling, ideally with greater cost effectiveness.  Technologies reviewed here use optical and acoustic methods, as well as autonomous underwater and surface vessels and aircraft to provide new options for fisheries research.  Aircraft have long been used for visual surveys of fish such as capelin which aggregate in very near shore waters where ship-based studies are problematic.  Recently developed airborne ‘fish lidar’ optical systems can determine species of fish and size them to an accuracy of roughly 1cm to depths of about 100m.  Airborne lidar methods have been used to spatially and temporally extend ship sampling of thin vertical plankton layers to assess their importance to fish.  Additional fish lidar studies with new smaller laser and computer systems that can be operated from small autonomous aircraft suitable for launch and recovery from fishery research vessels would facilitate more routine use in fisheries research.  Active acoustic systems have been developed for deployment from fisheries research vessels to ensonify large areas (on order of 1000km2) of continental shelf to allow synoptic studies of fish in the water column.  These Ocean Acoustic Waveguide Remote Sensing (OAWRS) methods also need to be further employed by researchers.  Autonomous underwater vehicles (AUVs), especially gliders, are now used to track tagged fish to document habitat use, and can also be used to study predator-prey interactions.  Recently developed wave-powered autonomous surface vessels (ASVs) equipped with various sensors also allow fish habitat studies over long periods of time, and are particularly useful in remote areas.  In addition to data collection, ASVs can be integrated with AUVs as communication nodes so that AUVs need not interrupt sampling to surface for data transmission.  Examples of these systems are described for specific fishery research projects.