Orcas of the Johnstone Strait
As a kayak guide, a large part of your job is being knowledgable about the environment and ecology of the area in which you are guiding. Without a formal background in geography, marine biology, ecology, or really any related field, I have done a lot of this research individually. I have compiled this information about the Orcas of the Johnstone Strait and I present to the guests during an evening of our tour to give them information about the whales that we may be lucky enough to see.
Before getting into all of the information about orcas, also known as orcinus orca in Latin, I think we should talk about their other name—the killer whale. Now this name surely has a negative connotation and stems from a miscommunication between Spanish and English Mariners in the early 18th century. The Spanish called these whales “ballena asesina” which translates to the killer of the whales as they had observed orcas taking down larger whales when exploring the Atlantic. The English mistranslated it to killer whales and the name has stuck ever since.
This perpetrated that orcas were feared predators in the ocean and, in the case of the European fishermen in the Johnstone Strait and surrounding regions, that they were not vital parts of the ecosystem. These fishermen believed that there were thousands of orcas and that they were the ones who were eating all of the salmon. They would shot and kill these whales on site believing that their populations were growing and threatening threatening the fish stock. In 1961, the fishers went as far as to petition the DFO which resulted in them installing a machine gun on a lookout on Quadra Island for the sheer purpose of gunning down whales. Thankfully this gun was never fired, but this goes to say how widespread this hatred of the orcas was.
Things started to change in the early 1970s, much to the credit of the scientist Dr. Micheal Bigg and his colleagues. Together they organized a count of these whales over the entire inland stretch of Vancouver Island. When he was hired as the head of marine mammal research at the DFO, he was responsible for running the census to asses the true number of these whales. On July 27, 1971, fishermen, lighthouse keepers, boaters, and others who frequented the coast were tasked with counting the whales. The true number, which was found to be accurate when the survey was repeated with photo validation was somewhere around 250, dwarfing the thousands that were believed to be roaming the sea.
Through this work, Dr. Bigg and his team also began to understand the field of photo-identification. Orcas can be identified by their dorsal fins and saddle patches (the white/lighter coloured patch behind the dorsal fin). This was the start of the identification of these whales and scientists were then able to gather information about their movement patterns and social relationships. This also where the different sub-populations of the Orcas were found and allowed scientists to differentiate them.
There are 3 groups of Orcas that live in the Johnstone Strait: the offshores, the Biggs (also known as the transients), and the Northern Residents. These different groups are whats known as divergent populations. Genetically, they are all the same species; however, the groups will not inter-breed with each other and exude different characteristics and behaviours.
We’ll start with the offshores, as they are the least likely to be seen in these waters. They spend most of their time around the continental shelf off the west coast of Vancouver Island and are rarely seen. Little is known about them, but there have been clues from remains that have led Scientists to certain conclusions. Mostly this is about their diet, which is believed to be largely sharks and fish. This discovery comes from the fact that when performing necropsies on offshore orcas, they would find that their teeth are extremely worn down. Shark skin is rough like sandpaper and wears down the orcas teeth. Often times the orcas will target the sharks livers, the fattest and most nutritious part of the animal, and leave the rest for the other scavengers in the ocean to sustain themselves from. This preserves their teeth and avoids them being worn down to the gums. They normally travel in large groups and are rarely seen in these inshore waters.
The next group is the most distinct: the Biggs orcas. These were previously names the transients but were renamed in Dr. Bigg’s honour. This group is the mammal hunters. Eating all types of marine mammals from seals and sea lions all the way to dolphins and whales, it is believe these whales consume an average of one mammal a day. These orcas are silent hunters, not relying on echolocation so as to sneak up on their prey. Moving in smaller groups, they hunt silently and often times rely on blunt force trauma to injure or kill their prey. In the cases of taking down larger whales, they will use blunt force trauma to stun the animal then they will pile on top of the animal to drown it. A pointy, more triangular fin is a distinct feature of the Bigg’s and, should you be viewing them from the air, they are often times shorter and have larger skull. The larger skull is used to ram their prey in opposition to the residents and the shorter body is an adaptation to make them built for speed and power.
