Mysterious Killer Whales Come Inshore
Many Port McNeill (N. Vancouver Island, BC) residents were whale watching on the evening of March 30th and they didn’t have to leave their homes to do so!
A group of 12 offshore killer whales was extremely active right in front of the community; even repeatedly spyhopping (popping their heads out of the water). To have whales this visible near your home is a great gift but, all the more remarkable is that these were very mysterious, threatened whales.
“Offshores” are a distinct type of killer whale that does not mate with the killer whales that eat marine mammals (“transients”) nor with those that feed on fish, mostly salmon (“residents”).
About 300 individual northeastern Pacific offshores have been photographed but studying them is usually very difficult. As their name suggests, they are most often near the continental shelf and they are very wide-ranging. Offshores weren’t even identified till 1979 and weren’t confirmed to be a distinct population until 1989.
So little is known about them. Only very recently did the research of Dr. John Ford et al illuminate what the whales might be doing around the continental shelf and why their teeth are worn down so much more than the teeth of other killer whales. DNA analysis of prey samples confirmed that the diet of offshores includes Pacific sleeper sharks (4m+), a species with very abrasive skin that are found around the continental shelf. In some cases the offshore killer whales’ teeth are so worn down by the the sharks’ skin that it is believed they become dependent on the help of other offshore killer whales to catch and eat this prey. The offshores’ scarred bodies served as a further hint that they may do battle with sharks.
Their diet is believed to also include other shark species (e.g. salmon sharks, blue sharks) and halibut.
Inshore sightings of these whales provide a very unique opportunity to learn more about them e.g. what they are eating when inshore and why they are so full of toxins. It is puzzling that offshores killer whales appear to becoming inshore more often and this may be due to a shift in diet or range in their prey.
Luckily one of the world’s leading killer whale researchers, Graeme Ellis of the Pacific Biological Station, was able to join the offshores in front of Port McNeill for this research opportunity. He was alerted to their presence by the superstars at the Orca Lab (Leah Robinson and Marie Fournier) who first heard these whales’ unique vocals in the Robson Bight area on March 25th.
I too was extraordinarily privileged to be able to contribute some ID photographs from sightings on March 27th and . . . I don’t think I’ll ever quite be the same after watching these mystery whales surfing in 3’ waves.
It all just goes to show that you never know who you’ll meet on Northern Vancouver Island!
[Great thanks to residents of Port McNeill and Angela Smith of Ocean Rose Adventures for helping get photos of a lone male offshore killer whale in Port McNeill Bay on March 27].
For more information on offshore killer whales see:
- Draft Recovery Strategy for the Offshore Killer Whale (Orcinus Orca) in Canada
- Department of Fisheries and Oceans Management Plan for the Offshore Killer Whale (Orcinus orca) in Canada (includes natural history and analysis of threats)
- BC Cetacean Sightings Network information on offshores (includes vocals)
- Scientific study referred to in the blog: Ford JKB, Ellis GM, Matkin CO, Wetklo MH, Barrett-Lennard LG, Withler RE (2011) Shark predation and tooth wear in a population of northeastern Pacific killer whales. Aquat Biol 11:213-224
- January 2011 Vancouver Sun article “Orca off B.C.’s coast love the taste of shark – but they’re wearing their teeth flat on the abrasive skin of the sleeper shark, study says”( reporting on Ford et al’s research)
- Dalheim, Marilyn, Alisa Schulman-Janiger, Nancy Black, Richard Tenullo, Dave Ellifrit, Kenneth C. Balcomb, III (2008) Eastern temperate North. Pacific offshore killer whales (Orcinus orca): occurrence, movements, and insights into feeding ecology. Mar Mamm. Sci 24:719–729
- Committee on the Status of Endangered Wildlife in Canada (COSEWIC) assessment of offshore killer whales (they meet the criterion for “Endangered” but have been designated “Threatened”).
- Species At Risk Act (SARA) species profile