Hawai‘i's false killer whales

Pseudorca, or false killer whales, are a large toothed whale that lives in the tropical and sub-tropical open ocean. In Hawaiian waters there is a small population associated with the main Hawaiian Islands that are long-term residents, they are kama‘aina, truely Hawaiian, Pseudorca. More is known about Pseudorca in Hawaiian waters than anywhere else in the world, and they are one of the highest priority species for our Hawai‘i research program. Below you will find photographs and a variety of information on Pseudorca in Hawai‘i and elsewhere.

Pseudorca are uncommon everywhere - they are at the top of the food web, and like other top predators are naturally rare. A NMFS study of all of Hawaiian waters out to the international boundary found that false killer whales were the least abundant of the 18 species of toothed whales and dolphins found in Hawaiian waters.

A Pseudorca carrying a tuna, followed by its hunting companions. Photo (c) Deron Verbeck.

In Hawaiian waters Pseudorca regularly use near-shore areas. The island-associated population is genetically differentiated from Pseudorca in offshore Hawaiian waters (Chivers et al. 2007). Photographs obtained by researcher Dan McSweeney (of the Wild Whale Research Foundation, based in Holualoa) from the mid-1980s and 1990s have been used to demonstrate that this population has long shown fidelity to the area (Baird et al. 2008). The most recent population estimate for the insular population is just 123 individuals (Baird et al. 2005). Like the killer whale (not particularly closely related but with a very similar skull), Pseudorca are long-lived (into their 60s), slow to reproduce (having one calf only every 6 or 7 years), and do not start reproducing until their teens. Like humans, females go through menopause, and have a long post-reproductive period. Thus Pseudorca populations would be very slow to recover from any impacts from human activities. Also like killer whales, because they are long-lived upper-trophic level predators, they accumulate high levels of toxins and may be impacted by competition with human fisheries.

Our photo-identification work has demonstrated that Pseudorca have long-term bonds. They share their prey, not only with their companions, but also with humans. A Pseudorca that was alone in British Columbia and Washington from the late 1980s until a few years ago, far from their normal range off Mexico, repeatedly caught large salmon and would offer them to boaters. In Hawaiian waters, Pseudorca have offered fish to human snorklers and divers.

Pseudorca with yellowfin tuna. Photo (c) Dan McSweeeny/Wild Whale Research Foundation

A group of Pseudorca from the insular population. Photo (c) Deron Verbeck.

Recent evidence indicates the insular population of Pseudorca in Hawai‘i has declined dramatically over the last 20 years (Reeves et al. 2009). Five years of aerial surveys undertaken from 1993 through 2003 by Joe Mobley of the University of Hawai‘i West O‘ahu have shown a steep decline in sighting rates. Group sizes of the largest groups documented in surveys undertaken by Steve Leatherwood and Randy Reeves in 1989 were almost four times larger than the entire current population estimate (Reeves et al. 2009).

This graph shows a significant decline in the sighting rate of Pseudorca around the main Hawaiian Islands in aerial surveys undertaken by Joe Mobley of the University of Hawai‘i West O‘ahu (with thanks to Joe Mobley for providing survey and sighting details). These surveys were undertaken at the same of the year each year covering the entire main main Hawaiian Islands.

Mother and calf Pseudorca, December 10, 2008. Photo (c) Robin Baird.

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To help raise awareness of Pseudorca conservation and management issues within Hawai‘i we have created and printed two versions of a brochure for the general public. These brochures are being distributed through the Hawaiian Islands Humpback Whale National Marine Sanctuary education programs as well as through other venues in Hawai‘i. PDF copies of the brochure (meant for printing double-sided) can be downloaded by clicking on the photos above. Left photo (c) Doug Perrine/SeaPics.com - all rights reserved. Right photo (c) Deron Verbeck/iamaquatic.com. If you are interested in printed copies of the brochure for distribution please contact Robin Baird at rwbaird (at) cascadiaresearch.org

Maps and photos from recent field projects where we've encountered Pseudorca

During field projects in Hawai‘i we post regularly updates on sightings and often include maps of movements of satellite tagged individuals etc. We encountered Pseudorca during several recent field projects - you can find links to the project updates below.