Assessment of Re-sighting Rates of Previously Dart-Tagged False Killer Whales and Short-Finned Pilot Whales in Hawai'i: A Preliminary Report Taking into Account Re-sighting of Social Groups.

摘要

Understanding the impacts of invasive research techniques is critical to ensure that such research activities will not have detrimental effects on populations under study. In Hawaiian waters we have been using remotely-deployed dorsal-fin attached Low-Impact Minimally- Percutaneous External-electronics Transmitter (LIMPET) satellite tags (Andrews et al. 2008) to examine movements and habitat use a number of species of odontocetes (see e.g., Schorr et al. 2008, 2009; Baird et al. 2010, 2011a, 2011b; Woodworth et al. 2011). Early re-sightings of previously tagged individuals of several species with complete healing of the tag attachment sites suggested that impacts of tagging were minimal (Hanson et al. 2008), however an assessment of re-sighting rates of tagged versus untagged individuals has not yet been undertaken. With funding from the National Oceanographic Partnerships Program (NOPP) and the Office of Naval Research, we are conducting follow-up studies on tagged whales to assess the effects of tagging on survival and reproduction. These studies are utilizing information from several species for which there are both reasonably large samples of previously tagged individuals (in particular false killer whales and short-finned pilot whales), and for which there are long-term photo-identification catalogs available for assessment of social organization and re-sighting rates. There are resident populations of both of these species around the main Hawaiian Islands, individuals are easily approached and the majority are distinctive, and encounter rates are high enough that there is a relatively high potential for re-sightings. Both false killer whales and short-finned pilot whales exhibit strong social bonds (Baird et al. 2008, 2011c; Mahaffy et al. 2011), although groups encountered in the field are often larger aggregations that include one or more smaller, more stable, social units.