The humpback whale (Megaptera novaeangliae) is the one of the most well-studied whale species. The genus Megaptera means “large winged,” highlighting its long pectoral fins and broad tail fins or flukes, which it slaps on the water's surface in enormous displays. This whale has become renowned for these displays. They are also famous for their songs, which the males sing during the breeding season.
Description
Humpback whales are dark grey or blue-black with unique patterns of white on their pectoral fins, undersides and flukes. They are easy to distinguish from other whales by the hump found on their back and their relatively large pectoral flippers. These flippers can be up to a third of their body length and are serrated, as are their flukes. The combination of the serration and the patterns of white colouration on their flukes is unique to individual humpback whales and can be used to distinguish one whale from another, like a fingerprint. Adults are around 11 to 16 m long and weigh around 25 to 35 tonnes but can reach up to 45 tonnes. These whales have knobs with sensory hairs on the top of their head and their lower jaw that help them maneuver in the water. As filter feeders, humpback whales have deep skin folds along their underside called rorqual grooves, which allow them to expand their mouth and throat during feeding to engulf larger volumes of water that will be filtered through their baleen. Females are, on average, larger than males, but these whales can also be sexually distinguished by the presence of a calf for females or the detection of singing for males.
Distribution and Migration
Humpback whales are found in all oceans, from cold and food-filled polar waters to warm, tropical environments. These whales complete one of the longest mammal yearly migrations, with some swimming up to 8,000 km. Humpbacks spend their summers at high-latitude feeding grounds where the waters are very productive. There, they feed and build up energy stores for the winter. In the late summer and early fall, they migrate to spend their winter in lower-latitude, less nutritious tropical waters. During the winter, they will eat very little and use their energy stores for sustenance. These warm tropical waters are mating, calving and nursery grounds for these whales. Although most humpback whales follow similar migration patterns, there are many distinct populations throughout the oceans that do not cross over.
Reproduction and Development
During their winter stay in tropical warm water, humpback whales prefer shallow waters near offshore reef systems or lagoons. There, adults will mate. Males can be very aggressive at the breeding grounds as they compete for better access to females, and they will sing a long, complex song that changes every breeding season. Mothers will then undergo an 11-month gestation period before giving birth to a 4–4.5 m and 1–2 tonne newborn. The calves will remain near their mother for a year before weaning. During this year, they will have a close relationship, and their mother will be very protective. Mother and calf will often physically touch each other while remaining in shallow, sheltered waters. Once the calf has gained enough weight and strength, they will migrate to the polar feeding grounds. Female whales only calve every 2–3 years, but some individuals have been observed to calve annually. These whales will reach sexual maturity after 4–10 years but are only considered full-grown by 12–18 years old. Humpback whales can live up to 80–90 years.
Behaviour and Feeding
Humpback whales are baleen whales, meaning they eat very small food such as krill and small fish that they filter through the baleen plates in their mouths that act like a sieve. These whales will hunt using group-coordinated techniques such as bubble netting, where the group will push a school of fish up toward the surface by surrounding them with bubbles. In the summer, they can eat up to 1.4 tonnes of food daily to build up their energy stores to survive the following migratory months. These whales are often found close to shore, where they are very active at the surface, breaching often and slapping their pectoral fins on the surface.
Whaling
Due to their slow swimming and habit of spending most of their time near the surface, humpback whales were easy targets for whalers. They were overexploited for commercial whaling for centuries until 1966, when the International Whaling Commission banned commercial humpback whaling to prevent their extinction. By 1985, their populations were reduced by more than 95 per cent compared to historical numbers. Despite a global moratorium being placed on whaling in 1985, the humpback whales are still recovering and have yet to reach their pre-commercial-whaling population estimates.
Threats and Conservation
Humpback whales are currently listed as a species of least concern by the International Union for Conservation of Nature’s Red List of Threatened Species, though some subpopulations are considered endangered. The Canadian Species at Risk Act and the Committee on the Status of Endangered Wildlife in Canada list the North Pacific population of humpback whales as Special Concern.
Humpback whales are vulnerable throughout their range to vessel strikes and vessel harassment, but the risk is higher in coastal areas with increased boat traffic and underwater noise. Another threat to humpback whales is climate change and its effects on their winter feeding grounds. By changing the timing and distribution of sea ice, the distribution of their prey, such as krill, could change, leading to nutritional stress and diminished whale reproduction. They are also susceptible to entanglement in fishing gear, and most humpback whales experience entanglement at some point in their lives. While they can often shed the gear, some do not survive the entanglement. Their natural predators include orcas and great white sharks, which primarily target calves. The designation of Marine Protected Areas in their natural habitat can help protect humpback whales as it limits the boat traffic and industrial activities that threaten these animals.
Relationship with Indigenous Peoples
Many Indigenous Nations of Canada's west coast have had a strong connection with humpback whales going back millennia. The whales feature in many of their cultures and traditions, and historically have been hunted for subsistence. Nations such as the Haida, Heiltsuk, Nuxalk, Gitga’at, Makah, and Nuu-chah-nulth have a strong spiritual connection and view them as sacred animals that bring good luck and fortune. They have a deep respect for the whales and understand that they are an important part of the region's ecosystem, and frequently advocate for the species’ conservation and protection.