Recent research by scientists from the Whale Trust Maui organization in Hawaii found that humpback whales may be much more mobile during their breeding season than previously thought, and some travel up to 6,000 kilometers in search of mates.
Humpback whales, whose scientific name is Megaptera novaeangliae, are found in all major oceans. Those in the North Pacific often spend their summers feeding in Alaska and Canada before migrating south in the winter to waters near Mexico and Hawaii to breed.
Scientists had assumed that whales choose Mexico or Hawaii as their breeding ground. However, some evidence, such as the songs of this species of cetaceans, suggests that the two groups can mix.
Specialist James Darling, from Whale Trust Maui in Hawaii, and his colleagues studied the database of Happywhale photographs of more than 26,000 individual humpback whales in the North Pacific taken by professional and amateur photographers since 1977.
This was possible because whales have distinctive pigment markings on the skin on the underside of the tail that allow them to be accurately identified. Using software, the researchers recognized two whales that were photographed in both Hawaii and Mexico during the same winter breeding seasons.
One male had traveled 4,545 kilometers in 53 days, leaving a group in front of Olowalu on the Hawaiian island of Maui to join a group of three whales off Clarion Island in Mexico's Revillagigedo archipelago in 2006.
A second whale, probably also a male, had traveled 5,944 kilometers from southern Zihuatanejo in Mexico to the waters of the ʻauʻau channel off Maui, where it was seen 49 days later, in the winter of 2018. There, he was one of the seven whales that chased a single female, as a challenger of his main companion.
“Our first reaction was, 'you have to be joking! '” , Darling told New Scientist. But distances that seem enormous to humans may not be significant for whales. “They could be traveling across the ocean as if it were their own backyard,” he explained. “This really changes the way we think about whales.”
In the summer months, observers had seen these two animals in the northern feeding areas off the coast of Canada and Alaska.
While the matching photos in the study showed males, females may also be making these long journeys, Darling considered. “If males were following females, it would make more sense than them swimming alone for 40 days without the females during the breeding season,” he said.
Whales usually travel at sailing speeds of around 4 kilometers per hour, Darling said. Even if these whales had been photographed exactly on their departure and arrival dates, calculations suggest that they swam faster than this.
The findings indicate that there are no distinct populations of whales in the northeastern Pacific, but rather several overlapping groups, Darling concluded. If this is the case, it could raise important questions about the conservation status of humpback whales.
“The results also question the rules on the conservation status of whales,” the researcher said. Since the 1990s, for example, whales that hibernate in Mexico are considered endangered, while whales that hibernate around Hawaii are labeled as “not at risk.”
The study comes shortly after scientists combined satellite tracking data from 845 whales to create the world's first whale migration map.
The map was created by the conservation charity WWF, and shows a sort of oceanic superhighways that whales use to travel around the world. It highlights the growing threats faced by the world's whales in their key habitats and the blue corridors they use to migrate.
WWF is now calling on countries to take steps to safeguard marine mammals along their journey areas.
Chris Johnson, who leads WWF's whale and dolphin protection initiative, said that “the cumulative impacts of human activities, including industrial fishing, collisions with ships, chemical, plastic and noise pollution, habitat loss and climate change, are creating an obstacle dangerous and sometimes fatal. course. '
Humpback whales live in oceans all over the world. They travel incredible distances every year and have one of the longest migrations of any mammal on the planet.
Since they travel so many kilometers from tropical breeding grounds to abundant and colder feeding grounds, it is difficult to estimate the size of the population, according to the U.S. National Oceanic and Atmospheric Administration (NOAA).
Of the 14 distinct populations, it is estimated that 12 have more than 2,000 humpback whales each and two have less than 2,000. Some populations (such as those in eastern and western Australia) are thought to exceed 20,000 animals, a remarkable recovery given that the same populations were nearly eradicated by whaling nearly sixty years ago.
In contrast, the smallest known population is the one that lives in the Arabian Sea throughout the year and can count as few as 80 individuals.
Threats to humpback whales include the decline in foods such as krill due to a combination of climate change and industrial-scale fishing.
Humpback whales can become entangled in many different types of items, including tie-downs, traps, pots, or gillnets. Once entangled, if they are able to move the equipment, the whale can crawl and swim with the attached equipment for long distances, ultimately resulting in fatigue, compromised feeding ability, or serious injury.
There is evidence to suggest that most humpback whales experience entanglements over the course of their lives, but they can often dispose of equipment on their own. Unintentional boat collisions can injure or kill humpback whales.
Humpback whales are vulnerable to boat collisions throughout their range, but the risk is much higher in some coastal areas with heavy ship traffic.
In addition, underwater noise threatens whale populations, disrupts their normal behavior and drives them away from areas important for their survival. Sound has been shown to increase stress hormones in your system and mask the natural sounds that humpback whales require to communicate and locate prey, as highlighted on the NOAA website.
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