Melon-headed whales in Hawai‘i
Melon-headed whales underwater, photo (c) Deron Verbeck/Iamaquatic.com
Melon-headed whales are a poorly-known tropical oceanic odontocete. They are only infrequently encountered in Hawaiian waters. In our study we've encountered groups an average of every 14 days on the water (every ~1,500 km of search effort). Group sizes are variable, ranging from a single animal to 800 individuals, but typically they are found in the largest groups of any species we encounter (median = 287 individuals). Although they are not the primary focus of our work, for every group we encounter we collect identification photographs (over 30,000 to date), biopsy samples for genetics, stable isotopes and toxicology studies (120 to date), and since 2008 have been deploying satellite tags to examine movements (12 deployed in 2008). In July 2011 we published a paper on results from some of the satellite tagging work - to download a copy click here.
Three melon-headed whales, photo (c) Robin W. Baird
Melon-headed whales whales are closely related to false killer whales, short-finned pilot whales and pygmy killer whales, all of which are found in Hawaiian waters. The are most frequently confused with pygmy killer whales.
Download the above for information on how to distinguish between pygmy killer whales and melon-headed whales.
Dorsal fins of two melon-headed whales showing the notches that are used to identify individuals, photo (c) Robin W. Baird. Jessica Aschettino's Master's thesis from Hawai‘i Pacific University used the photos we've obtained to assess population size, population structure and movements of individuals. One unexpected finding is that there appears to be two populations of melon-headed whales in Hawai‘i, a large population of individuals that move frequently among the islands that utilizes deep waters, and a small population that is resident to the island of Hawai‘i that uses shallower waters. In September 2011 we published a paper on this work - to download a copy click here.
Melon-headed whales in Hawaii spend much of their time during the day logging at the surface resting, as in this photo. Photo (c) Robin W. Baird.
For more information:
Huggins, J., R.W. Baird, D.L. Webster, D.J. McSweeney, G.S. Schorr and A.D. Ligon. 2005. Inter-island movements and re-sightings of melon-headed whales within the Hawaiian archipelago. Presentation at the 16th Biennial Conference on the Biology of Marine Mammals, San Diego, CA, December 2005. Download PDF copy of poster
Ligon, A.D., R.W. Baird, D.L. Webster, D.J. McSweeney, and G.S. Schorr. 2007. Habitat preferences of melon-headed whales (Peponocephala electra) around the main Hawaiian Islands: implications for interpretation of the 2004 Hanalei Bay stranding event. Poster presented at the 17th Biennial Conference on the Biology of Marine Mammals, Cape Town, South Africa, November-December 2007. Download PDF copy of poster
- Aschettino, J.M., R.W. Baird, D.J. McSweeney, D.L. Webster, G.S. Schorr, J.L. Huggins, K.K. Martien, S.D. Mahaffy, and K.L. West. 2011. Population structure of melon-headed whales (Peponocephala electra) in the Hawaiian Archipelago: evidence of multiple populations based on photo-identification. Marine Mammal Science doi: 10.1111/j.1748-7692.2011.00517.x. Download PDF copy
- Woodworth, P.A., G.S. Schorr, R.W. Baird, D.L. Webster, D.J. McSweeney, M.B. Hanson, R.D. Andrews and J.J. Polovina. 2011. Eddies as offshore foraging grounds for melon-headed whales (Peponocephala electra). Marine Mammal Science doi: 10.1111/j.1748-7692.2011.00509.x Download PDF copy
- Aschettino, J.M. 2010. Population size and structure of melon-headed whales (Peponocephala electra) around the main Hawaiian Islands: evidence of multiple populations based on photographic data. M.Sc. Thesis, Hawai‘i Pacific University. 117 pp. Download PDF copy (this is a 13 MB file so you may need to right-click to download it)
- 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. Download PDF copy
- Aschettino, J.M., R.W. Baird, D.L. Webster, G.S. Schorr, D.J. McSweeney, and J.L. Huggins. 2009. Melon-headed whales (Peponocephala electra) in Hawaiian waters: A look at population size and structure. Talk presented at the 18th Biennial Conference on the Biology of Marine Mammals, Quebec, October 2009.
- Schorr, G.S., R.W. Baird, D.L. Webster, D.J. McSweeney, M.B. Hanson, J. Polovina, and R.D. Andrews. 2009. Satellite tagging of melon-headed whales in Hawai‘i reveals widely dispersed movement patterns. Talk presented at the 18th Biennial Conference on the Biology of Marine Mammals, Quebec, October 2009.
- Southall, B.L., R. Braun, F.M.D. Gulland, A.D. Heard, R.W. Baird, S.M. Wilkin, and T.K. Rowles. 2006. Hawaiian melon-headed whale (Peponocephala electra) mass stranding event of July 3-4, 2004. NOAA Technical Memorandum NMFS-OPR-31. Download PDF copy
All photos are copyrighted and should not be used without permission.
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