The recent stranding (June 2016) of two false killer whales at Waimairi Beach, Christchurch was a rare event. The first stranding in eleven years and only the third ever South Island stranding, the last one being in 1984. For many people it was also the first time they have heard about these charismatic whales.
Like its namesake, the false killer whale (or Pseudorca) is a member of the dolphin family. The somewhat unfortunate name is derived from similarities in skull morphology between the false and the ‘actual’ killer whale (or orca). False killer whales have one of the widest global ranges of any cetacean but don’t seem to be particularly common anywhere. While they occasionally venture into colder waters, they are significantly more frequent at lower latitudes.
New Zealand research
Stranding and sighting records suggest that false killer whales are more likely to be encountered around northern New Zealand. There is a dedicated research program in New Zealand that has identified a small number of whales that return to coastal waters year after year. There are two stable clusters of around 75 individuals each and the two groups regularly join up. More research is needed to find out if these whales form their own small population or whether they belong to a larger and wider ranging group. Interestingly, the research has also revealed that false killer whales may form long-term associations with oceanic bottlenose dolphins.
A stranding risk
While false killer whale strandings are very rare, they can be as large as pilot whale strandings involving, at times, several hundred individuals (for example, 253 individuals in the Manukau Harbour in 1978). The close-knit social structure that was documented off northern New Zealand suggests that a stranding, involving an entire pod, is a real risk. The impact on the local population could therefore be substantial. Consequently, it is very important that false killer whales are correctly identified at strandings and at sea.
False killer whales are often confused with pilot whales and at first glance they do look very similar. However, once you know what to look for, telling the two species apart is quite easy!
At sea, the best clues are:
- Small, dolphin like dorsal fin
- Long, slender body
- No white markings
- Pointed head
- Often lifts head above water when surfacing
- Often breaches
- Often bow-rides
- Often seen with bottlenose dolphins
At a stranding, there are further identifying features:
- Small pectoral fins with a characteristic ‘elbow’
- Large, orca-like teeth
- Protruding melon in adult males
Individual false killer whales can also be identified by the markings on their dorsal fins. This requires a clear profile image of the fin. Photographs are very important as they help answer a number of questions about the individual and its population. In the latest stranding, photographs helped researchers to ascertain that neither of the two individuals have been previously identified in the groups sighted off northern New Zealand (or elsewhere). Good photographs could also help us establish if the refloated whale has joined another group.
The research program relies heavily on sighting reports from the public so if you encounter false killer whales, please let False Killer Whale Research know right away and take lots of photographs. Their sighting hotline is 0800 327 688 (0800 FAR OUT). For more information about sightings etc. visit their Facebook page.
Learn more about Project Jonah at: http://www.projectjonah.org.nz