At present, only one species of killer whale (Orcinus orca) is recognized globally and there are thought to be more than 50,000 individuals that can be found across the globe. The killer whale populations around the coast of British Columbia are the most studied cetaceans in the world and it is where I have spent the last three months in order to learn more about them. In British Columbia, there are three ecotypes: Offshore, Resident, and Bigg’s (previously called Transients) killer whales. These ecotypes are all distinct from one another in morphology, behaviour, acoustics and genetics. They do not communicate with each other, socialise or interbreed. There is now a great deal of work which suggests that they might actually be separate species of killer whales.
The offshore killer whales number approximately 300 individuals but they are rarely encountered and so they are the least well known. They travel in large groups and are acoustically active, feeding on fish and sharks. Their diet on sharks which have rough skin causes their teeth to get worn right to the gum line. Bigg’s killer whales are mammal-eaters, primarily feeding on harbour seals, harbour porpoises and sea lions. There is thought to be approximately 500 individuals, with about 300 of these regularly occurring in the inshore coastal waters. They have large home ranges, with some showing a degree of site fidelity to a few locations, visiting every year. However, their movements are unpredictable and there are still a lot of unanswered questions about them. The resident killer whales are the most studied having predictable distributions, particularly in the summer where their movements are dictated by the presence of Chinook salmon. There are two populations of resident killer whales, the northern residents (in the Johnstone Strait) and the southern residents (near the San Juan Islands and Haro Strait). Overall, the number of northern residents is 254 and the southern residents is just 84. The Southern resident population in particular was severely reduced during the 1970s by captures for the aquarium trade. Their number is still low and they are listed as Endangered. Resident killer whales live in extremely close family units, called matrilines, with sons and daughters living with their mother for life, sometimes up to three of four generations all living together, every single day for life.
Due to the ground breaking work by the late Dr Michael Bigg, it has been possible to identify nearly every single killer whales in the British Columbia by use of photos of their dorsal fins and saddle patches which are all unique. For decades, killer whales have been studied using dorsal fin photos, mostly by boat based surveys to understand their social organisation, genetics and vocal dialects. However, Vancouver Aquarium’s Dr Lance Barrett-Lennard, and his colleagues Dr John Durban and Holly Fearnback (NOAA) are leading the way on novel insights into the health of killer whales in British Columbia using drones. Flying above the whales to take photos of them provides a different perspective on the whales. Lance and his colleagues are able to assess the condition of each whale by measuring the length and width of the whales using a technique called photogrammetry. Whale condition is linked to foraging success, and so the more the killer whales can find the Chinook salmon that they feed on in the summer, the better their condition will be. What this essentially means is that we can determine how fat and healthy they are or how close to starvation they might be. The hope is that his work continues for many years in the future and becomes a tool for long-term monitoring to help identify when the whales are nutritionally stressed, before they begin to starve. Working with fisheries managers, this could mean that if the killer whales are showing signs of low food source, fisheries could be restricted in the areas that are most important to them so they have access to prey.
I spent the best part of June and July looking through thousands of these photos identifying each individual so that Lance and his team can track inter-annual variability for each individual and identify the ones that are losing weight. This technique can also be used to identify pregnant females from as early as 5 months and so it can also help scientists calculate the rates of miscarriage in killer whales and also keep an eye on our soon-to-be mums.
For more information on the marine mammal research being conducted by scientists at Vancouver Aquarium click here: http://www.vanaqua.org/act/research/cetaceans
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Several years ago, I read a book that inspired me so much, I travelled to the other side of the world in the hope of experiencing a glimpse of what the author did. The book ‘Orca: the whale called killer’, written by Erich Hoyt in 1981, has been a constant seller over the decades. Hoyt eloquently describes his summers in the 1970s spent following a resident pod of orcas in the beautiful, rugged and wild Johnstone Strait off Vancouver Island in British Columbia. Through his close encounters with the oceans’ apex predators, he realised that these creatures are not the fearsome, voracious predators they were believed to be. Instead, they were intelligent, gentle and compassionate. The stories of the families he told - the calves born, the old ones lost, the intimate moments shared and the pressures they faced. I was hooked. I just had to see them for myself, to be there in that place and to hope of having the same up close and personal encounter as he did. So I travelled to Telegraph Cove, an old quaint town in the middle of nowhere, on the northern end of Vancouver Island. From there I kayaked down the Johnstone Strait to just outside the Robson Bight Ecological Reserve. For four days, we paddled up and down these waters, constantly scanning the horizon for a glimpse of them.
At one point we thought we saw dorsal fins in the far distance. My heart began to race, through excitement that I might finally get to see them up close and also through an element of fear, for that very same reason. Have no doubts, these are large creatures, robust and strong. They could snap my kayak in half without a second thought, flip me out and leave me helpless at their mercy if they wanted. But deep down I knew this would not happen. There is not a single incident in the wild of a killer whale harming a human. They are frequently in close proximity to boats and kayakers and seem much less interested in us than we are of them. We are just another thing to navigate and at best, momentarily inspect. As it turns out the distant dorsal fins were just some floating logs. My disappointment was palpable. I left British Columbia not seeing a single killer whale. I was frustrated but not dispirited.
Since then, I have travelled to the Hebrides in Scotland to encounter our West Coast Community (WCC) of killer whales. The WCC consists of just eight killer whales. This tiny population is genetically and culturally distinct from other killer whales that visit the bountiful but cold waters off Scotland. This family do not appear to mix with other killer whales and they have not been seen with a calf in the 24 years that they have been monitored. Given that they were all adults the first time they were identified by the Hebridean Whale and Dolphin Trust, it is now likely that they are too old to breed. This means that it is only a matter of time until one by one; the WCC will disappear.
I wanted to learn more about this population but my research about them has led me back to British Columbia. Killer whales here are the most studied killer whales on the planet. If I am to learn more about the WCC, I first have to learn all I could from the experts here. This time, instead of heading to the Johnstone Strait to see the resident population, I travelled to Tofino to work with the Strawberry Isle Marine Research Society, on the western side of Vancouver Island. The coastline of this peninsula is even more wild and rugged, buffeted by strong Pacific Winds that have gathered across the ocean from Japan. I came to Tofino to learn about the transient killer whales, or rather Bigg’s killer whales as they are now called. They are much more unpredictable in their movements and they have a large home range that stretches the entire coastline of British Columbia. They are not the fish-eating ones that Hoyt described; these specialise on other marine mammals such as seals, porpoises, sea lions and occasionally even bigger animals such as minke whales and gray whales. It is their diet of other marine mammals that defines so much for their life. Their distribution, communication and social structure are all likely determined because of their diet. The WCC in Scotland are also mammal eaters and so my instinct was that they are likely to be much more similar to the transient killer whales we see in the British Columbia than the residents.
Over the last three months I have been involved in some of the cutting edge research on killer whales and have learnt a lot about them and the other amazing marine mammals here. I have worked with experts at Vancouver Aquarium and I have read countless journal articles and wonderful books in my pursuit for knowledge. I look forward to sharing some of this in a series of blog articles in the coming weeks.