BackgroundThe Centre for Whale Research has been developing satellite tags for both humpback whales and blue whales since 2000. Working together with Dr. Nick Gales from the Australian Antarctic division, the tags have steadily evolved and miniaturized.
The ultimate goal of the satellite tag development project is to create a tag that will transmit spatial and temporal data from individual whales for periods as long as one year without negatively impacting on the animals’ health or behaviour in any way. Tracking an individual whales’ movements for a full 12 months will give scientists and managers unprecedented insight into the spatial and temporal requirements of these threatened and endangered species.
Our first model was a suction cup based surface tag with a small plastic (delrin) anchor that was designed to attach like a limpet. Shot from a medium power crossbow, this design failed to stay attached for longer than 16 hours! As the electronic components have miniaturized over the last three years we have moved from the surface mounted tag concept to a fully embedded tag. These tags, known as Electronic Discovery Tags or ED Tags, are designed to lie completely encapsulated in the whales’ blubber layer with only a small aerial protruding.
The limiting factor for data retrieval for any of these tags is a combination of battery life and tissue rejection. Because cetacean skin cells can grow as much as 200 times faster than human skin cells (presumably a response to limit natural biological fouling and to promote rapid wound healing), tissue rejection of the tag can be extremely fast. Scaled to human proportions the tags are smaller in dimensions than a hair follicle. Where a sliver may take up to a week to be sequestered from the human body, a similar scaled object inserted in a whale can be rejected in one or two days. Obviously the skin of an animal that is deals daily with barnacle scratches and shark bites in the marine environment must have a very active immune system.
Despite short attachment times, much has already been learned from deployments of these tags, particularly for pygmy blue whales. As the components for the tags continue to miniaturize, we anticipate enormous leaps in understanding of the migratory patterns of these whales. The success of these tags certainly hold the key to the future of whale migration studies. This site will be updated with the latest developments regarding this important new science.