Pygmy killer whales in Hawai‘i

Pygmy killer whales (Feresa attenuata) off Kona. Photo by Deron Verbeck. All three individuals in the photo have been documented numerous times, almost always together: in the foreground, HIFa012 in our catalog, an adult male, has been documented 25 times since 1996; in the middle, HIFa002, also an adult male, has been documented 28 times since 1994; in the back (far left), HIFa003, an adult female, has been documented 29 times since 1991 (all as of the end of 2010).

For copies of publications on pygmy killer whales click here

An inquisitive pygmy killer whale off the bow of our research vessel, off O‘ahu in October 2010. Photo by Robin W. Baird.

Two pygmy killer whales socializing. Photo by Daniel Webster.

The pygmy killer whale, a small toothed whale found in tropical oceanic waters world-wide, is one of the least-frequently encountered species of delphinids (oceanic dolphins) in the world. More is known about pygmy killer whales in Hawai‘i than anywhere else in the world, based primarily on a long-term photo-identification study undertaken by researcher Dan McSweeney of the Wild Whale Research Foundation, a non-profit group based on the island of Hawai‘i. Dan's observations have been combined with additional photo-identification effort since 2000 by researchers from Cascadia Research Collective, and results published in Marine Mammal Science in 2009. Additional photos were also provided by Tori Cullins of the Wild Dolphin Foundation, Deron Verbeck, and Beth Goodwin.

Pygmy killer whales are closely related to false killer whales, short-finned pilot whales and melon-headed whales, all of which are found in Hawaiian waters. The are most frequently confused with melon-headed whales.

Download the above for information on how to distinguish between pygmy killer whales and melon-headed whales.

Pygmy killer whale with healing injury on mouth-line, probably due to an interaction with a line fishery. Photo by Russ Andrews.

Although they are encountered only very infrequently, there is a small resident population of pygmy killer whales off the island of Hawai‘i. This is the first evidence of a resident population of this species anywhere in the world. Individuals have been resighted over periods of over 24 years (as of 2010), and there is evidence they use the area year-round. In addition, using photographs of individuals traveling together in the same group, it is clear that some associations among individuals are very stable, similar to the long-term associations seen in some other species of whales such as killer whales and short-finned pilot whales.

Pygmy killer whale rolling at the surface, December 2008. Photo by Robin Baird. Note the scarring on the mouth-line, probably due to interaction with a line fishery.

Because of the small population size the population is more at risk from human impacts than most species of whales and dolphins in Hawaiian waters. A stranded pygmy killer whale found dead on O‘ahu in 2006 had evidence of interacting with fishing gear (a hook and line injury in the mouth), and Hawai‘i is also home to regular naval sonar exercises that potentially could impact this species. With the very low encounter rates it will be almost impossible to determine whether the population is increasing or decreasing or monitor the impacts of such activities as naval exercises. Also, the standard methods NMFS uses for monitoring population trends, large-vessel line-transect surveys, will not be feasible, given the low encounter rates.

Pygmy killer whale off Kona. Photo by Dan McSweeney.

Two pygmy killer whales off Kona, December 2008. Photo by Robin Baird. A little bit of background on pygmy killer whales. Pygmy killer whales were first discovered based on two skulls, one described in 1827 and the other in 1874. The species was then effectively lost to science until 1952. The first six times live individuals were documented in the wild are worth reporting. The first live individual known to be of this species was harpooned, off Taiji, Japan, and brought in for processing. Although the individual was quickly flensed almost all the parts were obtained and the external appearance was recreated and described, along with the skeleton. The common name pygmy killer whale was first proposed based on this specimen by Yamada (1954). The second time this species was documented alive in the wild, off Senegal in 1958, the individual was captured and killed. The third known at-sea sighting was of a group of 14 individuals off Japan in 1963 - in this case the entire group was captured and taken into captivity, where all died within 22 days. The fourth recorded at-sea sighting of this species, also in 1963, ended a bit better, when only one individual in the group was captured and taken into captivity, this time in Hawai‘i. The fifth record of a live animal was an individual captured and accidentally killed in a tuna purse seine off Costa Rica in 1967. In the spring of 1969 a live individual was harpooned off St. Vincent. Finally, later in 1969, a group was observed in the Indian Ocean with none of them being killed or captured.

Pygmy killer whales resting underwater off Kona. Photo by Deron Verbeck. The individual in the foreground, HIFa006, is an adult female seen 21 times since 1994 (as of August 2010).

A pygmy killer whale calf with shark bite wounds. Photo by Dan McSweeney.

Another view of the pygmy killer whale calf with shark bite wounds. Photo by Robin Baird.

Pygmy killer whales prior to deployment of a suction-cup attached time-depth recorder/VHF radio tag, used to study diving behavior. Photo by Robin Baird.

Pygmy killer whales. Photo by Jay Barlow.

Cascadia Research and the Wild Whale Research Foundation are continuing studies of this species in Hawai‘i. In early December 2008 the first-ever satellite tag was deployed on a pygmy killer whale off the island of Hawai‘i to examine movements, and another satellite tag was deployed on a pygmy killer whale in April 2009.

Satellite tagged pygmy killer whale with companions (including HIFa006, photo above), December 7, 2008. Photo by Robin Baird.

For more information on pygmy killer whales:

Society for Marine Mammalogy Fact Sheet on Pygmy Killer Whale

Baird, R.W., G.S. Schorr, D.L. Webster, D.J. McSweeney, M.B. Hanson and R.D. Andrews. 2011. Movements of two satellite-tagged pygmy killer whales (Feresa attenuata) off the island of Hawai‘i. Marine Mammal Science doi: 10.1111/j.1748-7692.2010.00458.x Download PDF copy

Baird, R.W., G.S. Schorr, D.L. Webster, S.D. Mahaffy, J.M. Aschettino and T. Cullins. 2011. Movements and spatial use of satellite-tagged odontocetes in the western main Hawaiian Islands: results of field work undertaken off O‘ahu in October 2010 and Kaua‘i in February 2011. Annual progress report under Grant No. N00244-10-1-0048 from the Naval Postgraduate School. Download PDF copy

Baird, R.W. 2010. Pygmy killer whales (Feresa attenuata) or false killer whales (Pseudorca crassidens)? Identification of a group of small cetaceans seen off Ecuador in 2003. Aquatic Mammals 36:326-327. DOI 10.1578/AM.36.3.2010. Download PDF copy

McSweeney, D.J., R.W. Baird, S.D. Mahaffy, D.L. Webster, and G.S. Schorr. 2009. Site fidelity and association patterns of a rare species: pygmy killer whales (Feresa attenuata) in the main Hawaiian Islands. Marine Mammal Science 25:557-572. Download PDF copy

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