Gulf of Alaska | Mammals
First observations of harbor porpoise mating in Alaska & preliminary results from photo ID matching: Conservation implications for this elusive species in Kachemak Bay Presenter: Deborah Boege Tobin , ddtobin@alaska.edu, University of Alaska Anchorage-Kenai Peninsula College- Kachemak Bay Campus Josephine C. Shostak , jcshostak@alaska.edu, College of Charleston; University of Alaska Anchorage-Kenai Peninsula College-Kachemak Bay Campus Serena A. Tierra , satierra@alaska.edu, University of Victoria; University of Alaska Anchorage-Kenai Peninsula College- Kachemak Bay Campus Teresa Becher , tmbecher@alaska.edu, University of Alaska Anchorage; NOAA Alaska Beluga Monitoring Partnership Bruce Schulte , bruce.schulte@wku.edu, Western Kentucky University Marc Webber , mawebber@alaska.edu, The Marine Mammal Center; University of Alaska Anchorage-Kenai Peninsula College-Kachemak Bay Campus Harbor porpoises ( Phocoena phocoena ) have a reputation for being inconspicuous and until recently, their behavior has been poorly described, despite their common nearshore occurrence across much of the Northern Hemisphere. For the past seven years we have studied this species reliably in waters near Homer, Alaska, in conjunction with our team in San Francisco (NOAA Fisheries permit #20386). Herein, we describe our sightings and resightings (mark-recapture) to date, and our expanded pilot study defining habitat use and behavior of this species in Kachemak Bay. Additionally, we documented the first six observations of aerial behavior in this region using still and video imagery. A description of their mating habits in San Francisco Bay revealed that males often become fully or partially airborne as a consequence of their rapid sexual approaches to females (69% of mating attempts, n = 85) and that aerial behavior occurred only in a mating context. Furthermore, males always attempted to copulate by positioning their ventral side on the females’ left side (100% of approaches, n = 142), typically perpendicular to her level position at the surface. Mating may occur while traveling or aggregating for feeding and when calves are present. Researchers should be aware that rapid approaches to a conspecific and aerial behavior may be a sign of mating, rather than foraging, activity. We seek collaborators with photos or videos to identify this high-energy lateralized aerial mating behavior throughout Alaska. Observations of aerial mating, as described here, foraging behavior, and the presence of calves, should be considered when defining conservation hot-spots for harbor porpoises. In January 2021, the Kachemak Bay Critical Habitat Area, home to the largest NOAA National Estuarine Research Reserve, was reopened to personal watercraft (e.g., Jet Skis). For the first time since 2001 many species, such as marine mammals (harbor porpoises; sea otters; harbor seals; endangered Steller sea lions and fin whales, and potentially endangered or threatened humpback whales; killer and minke whales), birds (seabirds, marine waterfowl, and shorebirds), numerous fish and invertebrates, including some relied on by locals for subsistence harvests, not to mention phyto- and zoo-plankton, may be impacted by this vessel traffic. We plan to expand our study of harbor porpoises in Kachemak Bay to ultimately determine if such watercraft disturbance may affect their distribution and behavior.
Alaska Marine Science Symposium 2023 247
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