BC killer whale ecotypes – by Tim Silva

My Dear Reader,

It is a cold, rainy day here at Eagle Eye as I write to you. I do not mind the weather though, as the cause that I have pledged myself to, working with the Robson Bight Warden Program, is a noble one. As part of our purpose here is to educate, and partly of my own inclination, I feel it of great importance to write to you about the differences between the various ecotypes of Orca found here on the coast of British Columbia.

Killer Whale. Orca. Blackfish. These cetaceans are known by many names, and there have been many research hours put into understanding these amazing animals. However, to the average citizen the many divergent populations and their extensive differences that have been discovered may not be well known. To illuminate upon some of these variances let me begin by describing the most commonly sighted group here in the Vancouver Island area, Residents.

Resident Killer Whales are by far the most common sight during the summer months as they follow the yearly salmon runs in Georgia and Johnstone Straits. Residents are classified into two groups: Northern and Southern. The northern community consists of around 295 individuals, is listed as threatened and rarely ventures further south than Campbell River. Southern Residents only number around 78 individuals, thus are critically endangered, and are generally found in southern Vancouver Island waters. It is speculated that the southern residents are in their current state due to the capture of individuals for the aquarium trade during the 1970’s. They are having a hard time rebounding from this because of lack of food, increased vessel traffic and elevated pollution levels in those waters. Due to these factors, new calves unfortunately only have a 50% chance of surviving to adulthood (Northern Residents are faring much better than their southern cousins, with a 2.5% increase in population per year). Residents, as a whole, are salmon eaters, mainly focusing on the largest, fattiest salmon species found in these waters: Chinook, aka Spring or King. Due to their prey’s inability to hear them these whales are quite vocal, with each family group possessing their own variation on certain calls. Behaviourally southern residents tend to be very surface active while it is only the northern population that exhibits the beach rubbing behaviour often seen in Robson Bight.

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This activity is still not completely understood, but the most accepted current theory is that it is a culturally passed on behavior exhibited simply because it feels good. Though these two communities share many similarities they do not interact with each other, and mostly keep to their habitual areas. In the winter, the northern Residents turn their attention to Alaskan and offshore waters, with the southern community heading towards Washington and beyond. However, there is another ecotype whose roaming and vagrancy is so well known, it is even part of their name.

Transient Orca are the top predator of these waters. Recent research into transient behavior has shown that the same groups occupy our waters year after year making these Transients not as transient as originally speculated. To correct for this misnomer this ecotype is now being referred to as Biggs killer whales, after the late Dr. Michael Bigg, the pioneer to killer whale research in BC. There are a few key differences that you could use to distinguish these whales from the aforementioned residents and other Orca. For starters, Biggs tend to be the bigger of the BC ecotypes, and their dorsal fins are pointed at the tips, giving them an almost shark-like appearance. Their diet consists mainly of marine mammals, ranging from seals (harbour seals being the favourite) to dolphins and even smaller whales. On extraordinary occasions they have even been recorded hunting deer swimming between islands. Biggs are also the least vocal of the multiple ecotypes, typically only vocalizing when eating or socializing and undergo longer, more unpredictable dives. These habits all help them hide from prey that is constantly on the alert for their approach.

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Our final ecotype found off the coast of British Columbia are known by the name Offshores. We still have a lot to learn about this ecotype, but I will endeavor to tell you all I can. It is estimated that their population is over 300 individuals, they are roughly the same size as Residents, and live in quite large family groups. As the name suggests, they are found far from the coast near the continental shelf, and are rarely seen. One fact we do know is that their diet consists mainly of sharks. Initial evidence of their diet was provided by the fact that deceased Offshore whales teeth were found to be greatly worn down, thought to be caused by the rough skin of the sharks they seek. This theory was solidified when scientists following Offshores during their deep dives for prey were lucky enough to collect liver samples of Pacific Sleeper sharks floating to the surface. Travel patterns for this group are still largely unknown.

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Well there you are. A brief synopsis of the ecotypes of Orca found on our beautiful coast. If you wish to learn more, there are many fantastic books and papers written on the subject. Or if you so wish can find me at Eagle Eye, and I will answer any questions you may have. I hope you are doing well, and that we will meet someday. You know where to find me.

Sincerely,                                                                                                                                                               Tim Silva

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