False Killer Whales of Hawai‘i

By Dr. Ryan Jenkinson

A false killer whale and shearwaters. Photo by Annie Gorgone

It’s that time of year when the charismatic and well-known humpback whales begin to return to local waters for their winter residence. While they deserve the admiration and joy they bring to the people of Hawai‘i and the visitors that flock here to get a look at them, it’s worth taking time to give some attention to the lesser known whales and dolphins found around the islands.

There are seven species of mysticetes (baleen whales like humpbacks) and 18 species of odontocetes (toothed whales) that are known to use the Hawaiian archipelago as either permanent residents, seasonal visitors, or occasional passersby.

Toothed Whales

The toothed whales include the dolphins we commonly see in nearshore waters around the islands (spinners, spotted and bottlenose), some well-known species that are periodic visitors (killer whales and sperm whales), some cool and interesting species (three species of beaked whales, rough-toothed dolphins), and a group of smaller, dark-bodied whales commonly referred to as “blackfish.” These animals can be found in Hawaiian waters year-round.

Blackfish

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For those of us who spend time offshore fishing, working or just sailing the islands, the first glimpse of a “blackfish” can be quite intimidating as far as trying to identify exactly what we are seeing. There are four different species. The two smaller species are melon headed whales and pygmy killer whales. The flippers and head of the pygmy killer whale are slightly more rounded, and they have more distinct coloration on their bodies. They are shy little nuggets though, that rarely approach boats. The two larger blackfish species include short-finned pilot whales and false killer whales. The short-finned pilot whales are the most common and can be identified by the large dorsal fin well forward on the body and their large, rounded heads.

False killer whales probably get the most attention of the blackfish, and for good reason. They are really interesting, form tight familial groups that are unique to Hawaiian waters, feed in spectacular fashion on large pelagic fish, and are not too shy about approaching vessels. First thing to know about them – they are not killer whales! The name was derived from observations of fossils and their skulls, which are similar to killer whales, before any live animals were ever described. Their scientific name is Pseudorca crassidens (“false orca with thick teeth”). They grow to between 15-20 feet long as adults and can weigh up to 3000 pounds.

On the surface, the only trait we humans share with false killer whales is that we are both mammals. But when you look deeper into their life history, biology and social dynamics, it is easy to see why so many find these animals relatable and interesting. They are long-living (up to 60 years) but do not begin to reproduce until their teens. They do not have many calves (one every seix-to-seven years) and females go through menopause but still remain vital parts of the social structure after they stop giving birth. They live in tight familial and social groups and form long-lasting bonds. They hunt for cephalopods and pelagic fish (ahi, ono, mahi mahi, ulua) cooperatively and often share the catch with each other. In fact, they have been known to offer to share with humans, bringing captured fish up to boats and swimmers. On a side note: while that is an awesome behavior, we strongly suggest not jumping in the water if you run into false killer whales offshore. Just like humans, the behavior and attitude of individuals can vary quite a bit —some might be friendly and willing to share in their feast while others might be a tad more protective. It’s best not to find out which end of the spectrum a 20-foot, 3000-pound whale falls on through trial and error,

Hawai‘i Populations

A false killer whale and its calf. Photo by Robin Baird

False killer whales are found in warm waters around the globe, but the Hawaiian false killers live in three very distinct sub-populations, segregated by location, habitat type and social differences between the populations. The unique characteristics of each population have been demonstrated through photo-identification work (the distinct shape and scarring on the dorsal fin of individuals can be matched over time) and through genetic studies. Resource managers call these groups distinct population segments (DPS), and conservation actions vary based on our understanding of each. The waters around Kaua‘i and Ni‘ihau are the one area that all three of DPS groups commonly cross paths. Even when they are found in the same area, they do not interact or interbreed.

The offshore or pelagic DPS is usually found, well, way offshore. The best estimates indicate there are around 2,000 offshore false killer whales around Hawai`i, but their population trajectory remains unknown. These animals are most likely to interact with large-scale commercial long-line fishing operations.

The Northwestern Hawaiian Islands DPS is the least well-known of the sub-populations; and population estimates and trajectories are vague.

A false killer whale (Pseudorca crassidens) leaping. Photo by Robin Baird

The third DPS is known as the insular Hawaiian false killer whale stock. They are found in nearshore waters of all the main Hawaiian Islands and are the ones most of us are likely to encounter. Within this “insular” stock, five distinct social clusters have been identified with mating and social interactions usually confined within each cluster. This a problem, because the total number of insular false killer whales is estimated at less than 200 individuals. The genetic pool within each social cluster is not very large, and from a mating and long-term population management perspective, that is a problem.

The historical size of the insular population is unknown, but aerial surveys in the 1980s observed aggregations of up to 400 animals in a single area. Current estimates are that the population is decreasing about nine percent per year. Because of this, the insular DPS was listed as endangered under the federal Endangered Species Act in 2012. They are also protected under the Marine Mammal Protection Act and Hawai‘i Revised Statues Chapter 195D.

Having a Tough Time

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So why are these insular false killer whales, these cool and interesting and charismatic animals, having such a tough go of it? And what can we do to help? Well, to the first question, the answer is complicated and there is no single “smoking gun” to explain why there are so few remaining. Without long-term historical data to compare to, it remains hard to know exactly how many insular false killers once roamed our waters. There is plenty of evidence to suggest it was at the very least three-to-four times more than we see today. One likely cause is from inbreeding depression — when a population becomes so small that genetic variation is too low to sustain long-term growth (known as the Allee effect). Because they are large animals that feed high on the food web, they tend to accumulate toxins and contaminants in their bodies. This can lead to reproductive issues and diseases. It is possible that competition with local fisheries (we tend to target the same things they eat) has decreased food availability for them. And like most animals, they will take advantage of an easy meal, so interactions with fisheries can harm or even kill them. Many of the insular false killer whales show signs of interactions with scarring on their dorsal areas and heads from lines and hooks, and it is common to observe trailing lines from their mouths.

State and federal agencies, and private conservation and research groups work to better understand and protect Hawai‘i’s false killer whales. This is done through collecting tissue samples for genetic studies, instrumenting individuals to track their movements throughout the islands, estimating population size and social structure through photo-identification work, and continuing education and outreach programs to make fishers and the public more aware of these animals. Much of the research and on-water conservation is carried out under the direction of Dr. Robin Baird at the Cascadia Research Collective. Visit www.cascadiaresearch.org/hawaiian-cetacean-studies/false-killer-whales-hawaii for more information, photos and updates.

How to Help

A false killer whale feeding on ulua. Photo by Colin Cornforth

Learn to differentiate the blackfish species so we know if we are observing a false killer whale. Identification guides produced by CRC and the Protected Species Program at the state Department of Land and Natural Resources, Division of Aquatic Resources can be found at numerous fishing shops and harbors across the islands or can be requested through emailing kylaherr@hawaii.edu. Additional identification tricks, general life history information, management and research resources can be found at another CRC website (https://falsekillerwhales.org), NOAA Fisheries (https://www.fisheries.noaa.gov/species/false-killer-whale#overview), and a soon to debut DAR Protected Species page. Also, let us know when you observe false killer whales. Any photos of the dorsal fin (preferably directly perpendicular to the fin) are incredibly helpful. But all sightings are useful, photos or not. These sightings can be reported to the hotline at 800-747-7329, with photos sent directly to hawaii@cascadiaresearch.org or the PSP at kylaherr@hawaii.edu.

Finally, if you are out fishing and see a pod of false killer whales approaching, do your best to avoid interactions. Bring in your lines if possible and before you move on, take some time to enjoy these local, native Hawaiian animals. Hey, if you are nice, they might even bring a fish over to share. If you do happen to hook one, do your best to cut the line as close to the animal as possible (to reduce the amount of trailing line and drag). If you observe a hooked or injured whale, please call the hotline at 888-256-9840. Mahalo for respecting our local wildlife and lets all work together to make sure these rare and amazing cetaceans are around for the next generation and for many more to come.

• Ryan Jenkinson is a marine ecologist and fisheries biologist. He is the head of the Protected Species Program at the state Department of Land and Natural Resources, Division of Aquatic Resources. He can be reached at ryan.s.jenkinson@hawaii.gov