Meeting Abstract

10.2  Sunday, Jan. 4  New Minke Whale (Balaenoptera acutorostrata) Lunge-Feeding Processes and Behaviors KOT, B.W.; University of California, Los Angeles bkot@ucla.edu

Minke whales (Balaenoptera acutorostrata) are the smallest members of the filter-feeding rorqual whales (Balaenopteridae). Like most rorquals minkes feed by lunging into schools of fishes or krill with their mouths agape. They engulf a large volume of water and prey then channel it into their expandable ventral pouch. Musculature and elastic material properties of the pouch then generate hydraulic pressure that forces water back out the mouth through a set of baleen plates which retain prey. My investigations into the complex behaviors, processes and mechanisms central to this unique feeding system are possible because minke whales often feed visibly at the surface in my study area. During the summers of 2004, 2006 and 2007 I observed and obtained video footage of surface-feeding minkes from inflatable boats in the Gulf of St. Lawrence in eastern Canada. Individual whales were photographically identified and new photogrammetric techniques using digital video allowed me to determine some of the first acceleration and velocity information for lunge-feeding minke whales. I also calculated motions of the mandibles and ventral pouch which appear to play important roles in prey filtration. Over 100 feeding minkes were studied which allowed me to identify new aspects of their feeding processes and behaviors. I also conducted a short-term study which provided evidence that a minke whale with entanglement-like injuries to its ventral pouch had decreased feeding abilities versus five uninjured minkes in the area. Collectively this study demonstrates that new methods are revealing more information about the mostly misunderstood rorqual feeding system; it also suggests that more conservation measures are needed to help address the threats that fishing gear pose to whales with specialized feeding systems.