Meeting Abstract

36.5  Friday, Jan. 4  Comparative Kinematics of Lunge-Feeding in Rorqual Whales: Evidence of a Uniform Feeding Process KOT, B.W.; Univ. of California, Los Angeles bkot@ucla.edu

Rorqual whales (Balaenopteridae) are the largest animals on earth yet little information exists about their filter-feeding process due to the difficulties of locating and studying feeding whales at sea. Rorquals mostly feed by lunging into aggregations of fishes or krill with their mouth open. They engulf a large volume of water and prey which is directed into their highly expandable ventral pouch. Water is then forced back out of the mouth through a set of baleen plates which retain prey. Most previous work on rorqual feeding involved anatomical studies of dead whales or telemetric studies of living whales which were not seen feeding. Therefore, functional aspects of the feeding process remain highly speculative. My research involves capturing and analyzing film of rorquals while they are visibly feeding at the sea surface. I use digital video to comparatively quantify the lunge-feeding kinematics of four species of rorqual whales: blue whales (Balaenoptera musculus), finback whales (B. physalus), minke whales (B. acutorostrata), and humpback whales (Megaptera novaeangliae). I observe and film surface-feeding whales from inflatable boats in the Gulf of St. Lawrence in eastern Canada during the summer. Velocities of lunge-feeding and from key feeding anatomy (e.g. mandibles and ventral pouch) are calculated for each species. Results from 1300 hours at sea and over 3500 lunge-feeding events from hundreds of rorquals during 2004, 2006, and 2007 show variation, by species, in the anatomical motions of feeding. However, when scaled for body size the motions become very similar. This work provides evidence that rorqual whales use a somewhat uniform feeding process. It also documents some of the longest continual surface-feeding bouts ever recorded from individual blue, finback, and minke whales.