DV-09-016 A comparative study of morphology and dynamic buoyancy in cetaceans

Christie Mahaffey
5711 Boardman Hall
University of Maine
Orono, ME 04469

With so many diverse uses and activities in the waters of the Gulf of Maine, avoiding conflict or reducing impacts on rare native species like whales is a priority. This project aimed to study the physiological contraints in deep-diving cetaceans in the Gulf of Maine to understand how exactly whales react to conflict. Scientists have assumed that whales don’t have a problem with decompression when recovering from a rapidly dive, because their lungs collapse at a certain depth. However, recent research indicates that previous models of cetacean lung capacity and buoyance are too simplistic. Results from a tagging study by Mahaffey suggest a biomechanical model that allows whales to control their ascent from a deep dive in a way that accounts for decompression and conserves the animal’s energy stores.

Sea Grant funds supported Mahaffey’s travel to the Woods Hole Oceanographic Institution’s marine mammal stranding network laboratory to examine the lungs of recently deceased animals and collect crucial data to test whether she could determine the center of buoyancy in dead stranded animals at varying pressures representing different dive depths. Mahaffey successfully tested the concept on one cetacean and one pinniped, however the stranding season did not provide enough animals that were both small enough to fit in the pressure chamber and with minimal decomposition to produce a complete or publishable data set. The project did, however, demonstrate soundness of the experimental design and allow for comparison of the effectiveness of different tags. These data are useful to ongoing marine mammal projects and future collaborations.

One-year project, $5,000.