Estimating abundance of pygmy killer whales in Hawai‘i

Informing the conservation status of rare and elusive species is a common management challenge. Pygmy killer whales are a small, long-lived, cryptic delphinid species predominantly found in pelagic waters. Two genetically distinct populations/stocks of pygmy killer whales inhabit Hawaiian waters: a pelagic and main Hawaiian Islands (MHI) stock. The MHI stock is resident to the the main islands, that is, uses the area year-round and primarily occurs in near-shore regions. Their insular domain has enabled long-term studies on their population dynamics. Long-term (1988-present) photo-identification/resightings and social network analysis have provided evidence for two island communities: a Hawai‘i and O‘ahu community. Because these animals are only infrequently encountered, their conservation status is not well-understood; the most recent abundance estimates for the MHI stock were over 10,000 individuals, although only a handful of groups were encountered throughout the entire islands during the survey. The objective of this project is to obtain a more realistic abundance estimate for this population using mark-recapture methods, while accounting for spatially varying stock structure and phylogeny, in hopes to better inform the conservation status of this stock. Learn more about Cascadia’s work with Hawaiian pygmy killer whales here: http://www.cascadiaresearch.org/hawaiian-cetacean-studies/pygmy-killer-whales-hawaii.

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Michaela A. Kratofil
(she/her), Research Assistant