US Navy

Marine Species Monitoring

Visual Survey and Tagging of Hawaiian Odontocetes

Introduction & Objectives

As part of the long-term United States (U.S.) Navy-funded Marine Species Monitoring Program, Cascadia Research Collective (CRC) carries out vessel-based field efforts in conjunction with passive acoustic monitoring undertaken by U.S. Navy (Navy) scientists on and around the underwater hydrophone ranges of the Pacific Missile Range Facility (PMRF). The efforts are timed to occur immediately prior to the start of Submarine Command Courses (SCCs), to allow for collection of movement and dive data that could be used to examine exposure and response of cetaceans to Navy mid-frequency active sonar.

The purpose of the monitoring effort was to assess the spatial movement patterns and habitat use of cetaceans that are exposed to mid-frequency active sonar and how those patterns influence exposure and potentially responses. Results from this effort were compared with previous Cascadia Research Collective (CRC) survey effort and photo-identification and tag data from Kaua‘i, based on surveys in 11 different years since 2003. During the survey, the Marine Mammal Monitoring on Navy Ranges (M3R) system was used both to direct the research vessel to potential high-priority species and to inform the research vessel when only low-priority species were detected on the range, allowing it to survey off the range and thus increase overall encounter rates with high-priority species.

Technical Approach

Wildlife Computers SPLASH10-F satellite tags are funded by the Navy for deployment on Navy priority species, and additional tags are provided by Wildlife Computers or CRC for deployment on other species (e.g., humpback whales Megaptera novaeangliae). Tags are programmed to collect dive behavior and Fastloc®-Global Positioning System (GPS) data from the time deployed until three and a half days after the end of the SCC and continue to transmit the dive and Fastloc®-GPS data for an additional six days.

Data throughput of transmitting tags is limited by the availability of Argos satellite coverage (20 percent in equatorial regions improving to 50 percent at the poles). Wildlife Computers Motes are stationary, unattended ground-based listening stations which continually log telemetry data from satellite tags on animals within reception range (distances over 207 kilometers have been observed – see http://bit.ly/motestudy for more information). The received data are accessible online either immediately through a Wi-Fi/GSM connection or at a later date through physical USB download. Prior to 2017, a Mote receiver had been installed on Makaha Ridge on Kauai to support this project. In 2017, an additional Mote receiver was installed at Ni‘ihau to expand the monitoring capacity in this survey area. Motes work with, and enhance, the Argos system. They are always online, even when satellites are not in view, thereby significantly increasing data throughput for any tag within range. Data are uploaded to the Wildlife Computers Portal where they are easily viewed and managed by researchers.