OLI Grant: Digital Archival Tag to Study Harbor Porpoise Echolocation and Underwater Behavior
Grant Funded: 2006Harbor porpoises (Phocoena phocoena) are small toothed whales, which inhabit temperate and subarctic waters and use echolocation for foraging and navigation. They live in coastal areas where fisheries are active, vessel traffic is intense, and marine industries like offshore wind farms may be located. Harbor porpoises face mortality from entanglement in bottom-set gillnets or other fishing gear, entrapment in herring weirs, and behavioral disruption or habitat exclusion due to anthropogenic noise. Understanding how harbor porpoises use sound to navigate and to detect, select, and capture prey is critical for mitigating the effects of human activities on porpoise populations. Detailed information on harbor porpoise echolocation in the wild would also facilitate important studies comparing echolocation strategies between whale species and between captive and free-ranging porpoises. We propose to develop high-frequency audio recording electronics suitable for recording the click sounds of harbor porpoises. We propose to integrate that audio recording capability into the Dtag (an existing archival whale tag that records audio, position, and depth data), and to develop a housing and attachment system to deploy the resulting tag on harbor porpoises. We will first test the tag on captive animals; then we hope to deploy it on wild porpoises. The tag design and deployment project we propose will include both established investigators and students in an interdisciplinary collaboration between biologists and engineers. It will develop new tagging technology to observe in detail the underwater acoustic behavior and movements of harbor porpoises (and possibly other small whales as well). Finally, experiments with the tag will advance not only our understanding of porpoise echolocation strategies, but also our ability to mitigate anthropogenic impacts on porpoises and to mimic their abilities using custom engineered devices.