Once a target for whaling boats, now humpbacks draw whale watching crowds with their acrobatics, as they rebound from a history of being hunted.
Humpback whales (Megaptera novangliae) are found throughout the world. Their spectacular behaviours make them favourites of whale watching cruises. Although they travel long distances in the open ocean, humpbacks also spend significant time near the coasts. Humpback whales may enter estuaries, rivers and bays as they migrate along the coasts, sometimes at their peril. Studies of humpbacks are aided by their unique markings and lack of fear of humans.
Status and Population
Humpback whales are listed as Vulnerable by the IUCN, as Appendix 1 by CITES and as Endangered by the US. World population is estimated at approximately 6,000 animals. Humpback whales were one of the species targeted by whalers. More than 60,000 were killed in the early 1900s. Humpbacks have the most blubber of all the roqual whales relative to their size which made them valuable sources of oil.
In addition to habitat degradation and depleted food supply, pollutants such as DDT, PBCs, chlordane and dieldrin sequester in have been detected in their blubber. Levels are highest during feeding seasons and drop during breeding. This is most likely because they are feeding on fish and krill contaminated with these chemicals. They gain weight, mostly in blubber, during feeding season and utilize that blubber for migrating and breeding. Sadly, these toxins are also passed on to calves during nursing.
But the good news is that humpback populations are increasing and the north Atlantic stocks are coming back the strongest.
Whale Watching and Research
Today their economic and social value comes from their willingness to allow boats to approach and observe them. On their feeding grounds humpback whales generally ignore vessels that maintain a safe distance. In some cases the whales actually approach boats, so who’s watching who?
The undersides of humpback whale tail flukes are black and white, with each animal having a unique pattern. Using these patterns, many individual humpbacks are being studied over time. Whale watch boats assist in these studies noting the unique identification marks and comparing them with id books onboard. They then report which whales they have seen, their condition and what they were doing.
Some of the behaviours which make humpbacks so much fun to watch have a practical purpose. Slapping the water with their pectoral flippers or their tail flukes (called lobtailing) while swimming in a circle is part of feeding behaviour which may stun or confuse prey making for easier feeding. Flipper slapping is also seen during courtship. Body slashing and tail slapping can be aggressive behaviours aimed at other whales or boats that come too close. Breaching (coming completely out of the water) and spyhopping (coming headfirst out of the water) allows them to see what’s happening above the surface.
But watching humpback whales in the wild, it seems very likely that sometimes they’re just having fun.