Tracking data from male Narwhal shows whales regularly dive to depths of over 700m — ScienceDaily
The narwhal – the mysterious Arctic whale is known for its sword-like teeth – spends more than half of the time diving to find food, but can also last up to three days without meals, according to Manh A study by Cuong Ngô and colleagues from the University of Copenhagen, Denmark, was published in PLOS Computational Biology .
The narwhal is a deep dive whale that feeds on halibut, mackerel and squid. The researchers analyzed 83 days of continuous marker data for a single male Narwhal (Monodon monoceros) in the arctic waters of eastern Greenland. They also recorded a sudden drop in the temperature of the whale's stomach, indicating that the whale had been fed cold Arctic prey for the first seven days. They found that swimming can be divided into three types – swimming 50 meters from the ground, shallow for 50 to 350 meters, and deep diving between 350 and 900 meters. Although the author used data from a single person, the data set – which includes more than 8,500 dives – is the longest and most detailed record of whale diving activity ever studied. Such long-term records are difficult to obtain because tracking devices often separate after a few days or weeks.
Narwhals is believed to be affected by warming waters, competition with fisheries, and reduced sea ice caused by vessel disturbances. This research is the first step in understanding the diving behavior of these elusive creatures, which may ultimately help to design protection strategies to help protect climate change. The authors suggest that future studies should compare these baseline data with records of narwhals exposed to high levels of human activity.
"Advanced statistical methods provide unique insights into hidden deep-lying whales in the Arctic's pristine areas," said Susanne Ditlevsen, a senior research author. “We found a complex relationship between the characteristics of the diving modes under different behavioral states, which has not been found in cetacean research.”
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