We assess the potential for population structure of melon-headed whales (Peponocephala electra) around the main Hawaiian Islands based on photo-identification data from 2002 through 2010, to help inform genetic analyses of population structure and interpretation of data obtained from satellite tags. In addition, we compare photographs obtained from 1986-1996 to more recent photos to assess long-term site fidelity, and photos obtained from Palmyra Atoll from 2006-2009 to assess the potential for movements between Hawai‘i and Palmyra. Associations among individuals indicates the existence of at least two populations of melon-headed whales around the main Hawaiian Islands, a small population resident to the island of Hawai‘i (the Hawai‘i Island resident population) and a larger population of individuals that move throughout the main Hawaiian Islands (the main Hawaiian Islands population). Genetic samples are available from both populations and satellite tags have also been deployed on individuals from both populations. Re-sightings of individuals from the Hawai‘i Island resident population span up to 22.6 years and of individuals from the main Hawaiian Islands population span up to 13.1 years, indicating long-term site fidelity for both populations. There were no matches of individuals from Palmyra Atoll to Hawai‘i, however only a small number of identifications were available from Palmyra (66 distinctive or very distinctive individuals), thus comparisons of additional photos from Palmyra are warranted.
Citation:
Baird, R.W., J.M. Aschettino, D.J. McSweeney, D.L. Webster, G.S. Schorr, S. Baumann-Pickering and S.D. Mahaffy. 2010. Melon-headed whales in the Hawaiian archipelago: an assessment of population structure and long-term site fidelity based on photo-identification. Report prepared under Order No. JG133F09SE4440 to Cascadia Research Collective from the Southwest Fisheries Science Center, National Marine Fisheries Service, La Jolla, CA.
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