Sensory and Foraging Ecology in Baleen Whales - René Swift (University of St Andrews, Scotland)

René Swift, a PhD student at the University of St Andrews (Scotland), is currently undertaking a project to investigate the sensory and foraging ecology of baleen whales. Baleen whales, some of the largest animals to have lived on the planet, successfully feed on some of the smallest and most abundant prey, such as krill and forage fish. We still do not know how baleen whales detect and locate their prey. Unlike for toothed cetaceans the wave-lengths of sounds produced by baleen whales appear to be too large to detect small targets. Thus it would seem that baleen whales have evolved another method to effectively detect prey. The cues used to detect prey may include environmental signals, such as thermal fronts, and acoustic or chemical signals produced by the prey. To investigate these questions, non-invasive camera and accelerometer tags (data loggers that were designed and developed at the University of Tokyo, Japan) are attached by suction cup to humpback and fin whales. The whales are followed for the duration of the tag attachment (between 8 - 10 hours), with simultaneous surveys of the prey field, using the camera tag on the animal, and a hull mounted echo-sounder aboard the research vessel. This allows us to observe the whale's foraging movements in relation to prey density and distribution. During a preliminary study conducted in 2011, using these methods, Mr. Swift was able to confirm for the first time, that Gulf of St. Lawrence humpback whales switched from foraging in the water column to foraging on the seabed. During the coming fourth field season for this project, the focus will shift to fin whales, in order to compare the species. The data collect for nearly 30 humpback whales tagged over the last three seasons will require considerable time to analyze.