Long term autonomous fisheries survey utilizing active acoustics

摘要

Rising costs of ship time and increasing budgetary constraints limit current fisheries acoustic survey practices. The limited spatial coverage and relative infrequency of such surveys compromise their value to fisheries managers. The Liquid Robotics Wave Glider allows scientists to collect data in a wider range of weather conditions and using fewer man-hours than typical shipboard acoustic surveys while operating at a greatly reduced cost. As part of an NSF-sponsored research project, Cornell University, BioSonics, Inc. and Liquid Robotics collaborated to design and manufacture a custom tow-body containing a specially modified dual-frequency BioSonics echosounder with 70-kHz and 200-kHz transducers. The tow body was attached to the submerged glider unit of a Liquid Robotics Wave Glider with a compliant tow cable to provide mechanical isolation between the Wave Glider and the tow body. Liquid Robotics conducted a series of tests in Kealakekua Bay, Hawaii, during March 2011 and March 2012 with the goal of evaluating the ability of the system to detect the mesopelagic boundary community's (MBC) offshore to onshore and upward vertical migration. The system was shown to be an effective method for collecting high-quality acoustic data for studying patterns in the distribution and migration of marine organisms. It also holds great promise for applications oriented towards continuous assessment of commercial fish stocks and the monitoring of marine ecosystem health.