Abstract

The use of satellite-monitored radio tags to track the movements of large whales has yielded important information for conservation and management. Because almost all large whale satellite tags are invasive, often involving penetration through the blubber and across the fascia into muscle, there is concern regarding the implications of this methodology for the health of tagged animals. Previously, follow-up information to assess impacts of satellite transmitters on tagged whales was mostly opportunistic. Therefore little was known of the physiological consequences and processes associated with tagging, or the determinants of tag design or placement that improve methodological performance. A project designed to assess physiological effects of implantable tags on whales is being undertaken in a well-studied population of North Atlantic humpback whales (Megaptera novaeangliae) in the Gulf of Maine. The strong fidelity of individuals to particular feeding sites, long feeding ground residency, and strong overlap with observer effort (from dedicated scientific cruises and commercial whale watching operations) has resulted in repeated sightings of tagged animals. Since 2011, implanted satellite tags were deployed in 35 individuals of known age, sex, and with high probabilities to be re-sighted. Nineteen tags were deployed in 2011 with all but one whale being relocated within that summer season. Re-sightings were documented on an average of 10.6 days (min = 4, max = 22) since tag deployment, and with observations spanning 46.0 days on average (min = 6, max = 136). Tags deployed in 2011 transmitted for 23.8 days on average, with a maximum of 97 days in one case. Eighteen whales tagged in 2011 were successfully re-sighted during the 2012 season and coverage of those individuals now spans more than 400 days. In 2012, sixteen tags were deployed with 14 individuals being documented on an average of 7.6 days (min = 1, max = 14) since tag deployment, with observations spanning 43.3 days on average (min = 1, max = 79). Tags deployed in 2012 transmitted for 29.5 days on average, with three tags lasting for more than 80 days. Preliminary results have provided unique and unprecedented information on behavioral and physiological responses to tagging and on tag performance. Considerable variation was observed in behavioral responses, with some individuals exhibiting minor reactions and others showing pronounced, extended disturbance after tagging. There is also evidence that behavioral responses may be related to the animal's activity at the moment of tagging. For example, whales engaged in feeding activities showed less disturbance than travelling individuals. Physiological responses are also variable, with some whales showing minor local injuries while others presenting swellings, which in one extreme case has persisted for nearly 400 days. Such responses also appear to be related to the location of tag, with tags deployed laterally on the body showing more pronounced reactions than those placed closer to the body's dorsal midline. Finally, the high re-sighting rate achieved by this study has revealed tag design flaws and informed efforts to improve the technology.

Acknowledgements

Funding for this research is provided by the National Oceanic and Atmospheric Administration (NOAA) and Exxon via the National Oceanographic Partnership Program (NOPP) and the National Fish and Wildlife Foundation (NWFW). We particularly thank the following whale watching companies and affiliated organizations that have shared whale watching data with the project: Brier Island Whale and Seabird Cruises, the Dolphin Fleet, Captain John Boats, Blue Ocean Society, New England Coastal Wildlife Alliance, Whale and Dolphin Conservation Society and the Whale Center of New England.

* Presenting author