Background Information: Orcas, Humpacks and More!
Johnstone Strait is a deep and narrow glacier-carved passage located between the east coast of Vancouver Island and the British Columbia mainland. Bordered by Queen Charlotte Strait to the west and Discovery Passage to the east, gentle conditions prevail in the sheltered waters of Johnstone Strait and the nearby Broughton Archipelago.
Nutrient rich water from the deep, cold Pacific is funnelled into the gentler waters of northern Johnstone Strait with each tide. In late summer salmon return to the region to spawn and the largest resident pod of killer whales in the world, with a population of approximately 200 whales, congregates to feast. There is no better place to view these amazing marine mammals. In addition to the orcas, Johnstone Strait offers up a wide variety of other marine life, including Minke, humpback and grey whales, Pacific white sided dolphins, harbour porpoises, Dall’s porpoises, harbour seals, Steller sea lions and sea otters.
The Orca (Killer Whale)
The orca, or killer whale, is a toothed whale and is the largest member of the dolphin family. There are 3 distinct populations of these warm-blooded, air breathing mammals: Resident Killer Whales, Transient Killer Whales and Off-shore Killer Whales. Some biologists believe these populations actually represent 3 distinct, non-interbreeding species, but others challenge this assertion. Regardless, the main characteristics which set each of these populations apart are social behaviour, physical appearance, preferred food and vocal dialects. One of the best locations for viewing resident killer whales is off Vancouver Island in British Columbia.
Killer whales (orcas) are easily recognized due to their striking black and white coloration and a sleek, streamlined body shape that is tapered at both ends. The rounded pectoral flippers are used mainly to steer and, with the help of the flukes, to stop. The dorsal fin acts as a keel and helps to stabilize the killer whale and in males the dorsal fin is the largest of any of the cetaceans. The males or bulls start maturing at 14 years and reach full physical maturity at about 20 years. Most males reach a length of 8-9 metres and have a lifespan of between 40-60 years. The females or cows average about seven m in length and reach sexual maturity at 14-15 years and have a lifespan of 60-80 years. The gestation period is 16-17 months and a single calf is usually born. Newborn killer whales nurse for at least one year and mortality rates of calves is quite high.
The resident killer whales of the Johnstone Strait area eat predominantly fish (Chinook salmon being their preferred food but also lingcod, halibut, greenling and various small flatfish). Although they are often seen in the vicinity of other marine mammals they usually ignore them. In contrast, transient killer whales feed almost exclusively on marine mammals and seabirds.
Killer Whales often hunt cooperatively in groups (known as pods) for food. They work together to encircle and herd prey into a small area before attacking. Adult killer whales must eat approximately 3-4% of the body weight in food per day.
Resident orcas live and travel in pods organized along lines of maternal relatedness ranging in size from 3-50 individuals.
Orcas spend much of their time feeding or searching for food. They are deemed to be travelling when they are moving consistently in one direction in a relatively tight formation. They could be moving from one feeding spot to another or simply transiting an area. Resting is typically done after foraging and the whales group together, and dive and surface as a cohesive unit. They slow down or come to a complete stop and usually become quiet. Social behaviour among killer whales includes a wide variety of activities including breaching, spy-hopping, tail slapping, beach rubbing and flipper slapping.
Orcas can also be distinguished by the kinds of underwater communication sounds they produce – squeals, squawks and screams are used for social communication within and between groups. Studies have shown that these vocalizations differ between populations and pods, and can even be used by the whales to distinguish between individuals. Orcas also have acute hearing and vision both in and out of the water. Echolocation enables them to locate and discriminate objects by projecting high-frequency sound waves and listening for echoes. Orcas echolocate by producing clicking sounds and then receiving and interpreting the resulting echo.
Humpback Whales are also quite abundant in the nutrient rich waters around Johnstone Strait. Humpback whales are baleen whales that seasonally feed on tiny crustaceans, plankton and small fish. They are gulpers and therefore look for concentrated masses of prey which they can gulp in huge mouthfuls. On average a humpback whale will eat between 4000-5000 pounds of plankton, krill and small schooling fish each day in the cold waters of the north Pacific. Pacific humpbacks migrate south in the winter to give birth in the warm waters of Mexico and Hawaii.
Humpback Whales are well known for breaching and their complex songs. The name humpback whale describes the motion it makes as it arches its back out of the water then shows off its magnificent tail flukes in preparation for a dive.
Humpback Whales grow to an adult size of 17 m and weigh 40,000 kg. They can live for 45-50 years. They typically live alone or in transient small groups which come together for cooperative feeding. When the waters are super rich in nutrients many humpbacks can be seen together.
Our Marine Mammal Explorer trip gives a small number of visitors the unique privilege of observing orcas, humpbacks and many other species of aquatic mammals and marine birds over a number of days while staying on our floating base-camp – the beautiful Ocean Light II sailboat. There’s no better, or more comfortable, way to observe and photograph these spectacular animals!