Humpback is the star of the sea

EVERY animal group has its celebrity species.

The robin is our favourite bird, the salmon is the most perfectly-shaped fish and the lion has been crowned ‘king of beasts’.

The bottle-nose dolphin, the species to which Fungie belongs, is an iconic, toothed whale. Playful, intelligent and curious, bottle-noses press the right public-relations buttons. The great whales, which use sieves rather than teeth to hunt, are less cuddly, but they too have their superstar. The baleen species that draws the crowds is the humpback, a master performer on the maritime ‘stage’ and on TV.

Although in every ocean, humpbacks were rarely seen in Irish waters until recently. Only six were caught by the whalers working out of Blacksod in the early 20th century, and less than ten have been stranded on Irish shores since records began.

The number of humpback sightings has increased dramatically in the last few years, and, according to the Irish Whale and Dolphin Group (IWDG), these giants regularly visit our south and west coasts. This year looks like being excellent for them — four were seen off Kerry in recent weeks. The east coast is not popular with large whales, but a humpback appeared near Lambay last month, apparently for the second year in a row.

The name ‘humpback’ comes from the whale’s habit of hunching its back, dorsal fin aloft, as it starts a dive. The pectoral fins resemble enormous, white-and-black wings. Nobody is sure why they are so big. Are they the whale equivalent of a dog’s panting, the fins helping to dissipate body heat when the animal is in warm, tropical waters? Females are larger than males. A matriarch can be 17m long and weigh up to 40 tonnes. Fishing techniques include ‘bubble-netting’; shoals of fish near the surface are surrounded by bubbles released by whales swimming underneath them. The trapped fish are then attacked from all sides.

Not all that much is known about the social lives of whales, but it’s thought that associations between male and female humpbacks are of the short, ‘love them and leave them’ variety.

The most celebrated humpback display is known as breaching, a ritual which males perform during the mating season. I saw it once from a boat off the Galapagos Islands, an unforgettable experience.

A whale would rise vertically out of the water, arch backwards and fall back into the sea with a mighty splash. Humpbacks, it’s thought, don’t mate in Irish waters, but breaching was recorded here recently.

These sea giants are not just great dancers; whales are probably the most sophisticated vocalists of the entire animal kingdom, apart from ourselves. A humpback’s song, up to half an hour long, can be heard by other whales 30km away. Its structure is extraordinarily complex and each population has its own dialect. Individuals develop a repertoire that is changed from time to time. The function of the vocalisations in not understood; scientists are trying to unravel whale language. The songs may carry information that helps deter rivals or impresses prospective mating partners.

Not only is the humpback a hit with the public, it’s also the darling of the scientists. Marine creatures are difficult to study. We know almost nothing about the lifestyles of some whale species, but the humpback is a bit of a show-off and lets itself be studied. An animal’s entire body becomes visible during breaching and the black-and-white markings make it possible to recognise individuals. Each whale has its own, individual tail pattern and humpbacks lift their tails out of the water when diving. They also indulge in a water-beating display, slapping the ocean surface with their tails.

By photographing these, scientists can identify individuals. Subsequent sightings help reveal movement patterns. With enough data, associations between groups can be worked out and population sizes estimated.

The whale fluke database for our region is known as the North Atlantic Humpback Catalogue. More than 7,000 whales have been photographed to date. The number in the IWDG’s Irish humpback catalogue is 17 and rising.

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