Tools for tracking marine mammals and mapping ocean systems: evaluating and calibrating novel swim speed sensors

Archival biotelemetry devices record swimming speeds and ocean flow on marine mega fauna, mostly pinnipeds.  These utilize impeller type swim speed sensors.  These attach to the dorsal fur of the study subject using 2-component epoxy.  The animals subject the sensors to extreme conditions.  Shoreside, the impeller openings may become clogged with sand, in particular on volcanic islands where sand includes ferromagnetic components that tent to stick to permanent magnets used in impeller rotors.  In the Arctic and Antarctic, impeller ports and rotors may freeze.  Improving the current devices is ongoing and requires testing through various conditions.  To begin testing, the properties of the existing impeller swim speed sensors are documented and compared with novel differential pressure sensor designs at different water flows from 0.1 to 2.0 m/s as well as to susceptibility to mechanical abrasion, clogging and icing.  The information will provide new designs for collecting ocean flow speed and animal energetics, when coupled with GPS data, and implement improvements to existing archival biotelemetry devices that are scheduled for deployments on Wedell seals in Antarctica and Northern Elephant seals in California, in the fall of 2011 and spring of 2012.