Development of a CTD biotag: Challenges and pitfalls

This paper describes the design and development of a small CTD biotag that measures a suite of oceanographic data. Though presently configured to measure conductivity, temperature, and depth along with geo-location, it is expandable to acquire behaviorally related data, including acceleration, ambient light, and compass heading. The size of the instrument (100 mm x 40 mm x 20 mm) has been optimized for deployments on medium-sized marine predators such as penguins, tuna, and sharks. Several first generation prototypes have been constructed and initial laboratory and field tests have been performed and are reported. In addition, this paper highlights the challenges and difficulties encountered during the developmental process of a new biologging instrument.