oa Update on the use of an open source tri-axial accelerometer tag for monitoring whale shark (Rhincodon typus) behavioral disturbance

Background The rapidly decreasing cost of electronic components has enabled access to better tools for monitoring the behavior of whale sharks on a fine scale never before achieved. We use the new Kinematic tag (Oceans Forward) and the OpenTag (Loggerhead Instruments) as a novel approach to visualizing behavior of whale sharks. Fine scale habitat use and baseline behaviors are fundamental for understanding potential anthropogenic impacts of disturbance. Approach Each tag is an Arduino compatible open-source inertial measurement unit for recording motion sensor data to a solid state memory card. A three dimensional gyroscope, accelerometer and magnetometer allow for calculating pitch, yaw, and heading, while depth and temperature sample continuously. The rechargeable lithium battery allows for deployments up to 14 days sampling at 100 Hz. The Open Tag is placed in a hydrodynamic syntactic foam float, and banded around the dorsal fin. A galvanic release incorporated into the tag allows for a release time to be programmed and a VHF tag (Animal Telemetry Systems) aids in recovery. Trackplot (University of New Hampshire) was used to visualize behavior. Further analysis was conducted using Humu signal processing suite (Humu.io). Results Five tags were successfully deployed in the waters offshore of Cancun, Mexico between 2013 and 2015. Behaviors noted included frequent surface intervals, even during the night when previously believed whale sharks were normally in deeper waters. A maximum depth of 62.2 m was observed, with mean depth of 17.2 m. We were able to identify possible harassment at the surface and visualize possible defecation events. Conclusion Both the k-tag and Open Tags fill a unique niche in whale shark studies as a useful tool to better understanding of fine scale habitat use and behavior. By incorporating these data into Trackplot with data from potentially harassing activities such as vessel traffic, we can visualize behavior and investigate potential erratic changes in depth, heading and lateral movement amplitude indicative of harassment.