Restoration of whale populations will allow them to live up to 200 years - study

Bowhead whales may not be the only species that can live to be 200 years old. Researchers have found that commercial hunting of large whales has hidden the ability of these underwater giants to live to a great age, UNN writes with reference to The Guardian.

Details 

An article published in the journal Science Advances suggests that commercial hunting of large whales - sperm, blue, fin and bowhead whales - has "masked" the ability of these underwater giants to live to a ripe old age.

Since the 1990s, it has been known that Arctic bowhead whales, with their slow metabolism fueled by cold waters and abundant food, can live up to 200 years or more. This is also indicated by the dating of old Inuit stone harpoons found in bowhead whales that survived previous hunts.

However, a new study indicates that bowhead and fin whales may have the same life expectancy. The first scientific reports of "extraordinary longevity" emerged when scientists examined the ear plugs of fin and blue whales hunted by Japanese whalers in the late 1970s. By calculating the layers of annual growth of the ears, they found that animals that were thought to live to be 70 years old were at least 114 years old.

At the time, they were the oldest documented nonhuman mammals," the study authors say. "This extra-long age should not be unexpected. Whales are the largest living animals, and body size is closely related to life expectancy,

The moratorium on hunting large whales, introduced in 1982, has contributed to the increase in humpback and fin whale populations. Scientists suggest that without predation, the whales could have regained their natural life expectancy.

Conservationists also argue that there is an even more pressing reason for countries like Iceland and Japan to stop whaling. 

The scientists made their new findings by analyzing the life expectancy of two similar species: the southern right whale, which lives under the equator, and the North Atlantic right whale, which was once common off the coast of Northern Europe but is now almost entirely confined to the east coast of the United States. They found that up to 10% of thriving southern species live past 130 years of age. Of the northern species that are hunted, only 10% lived past 47 years. 

The population of the North Atlantic right whale, a close relative of the bowhead, is now so reduced after intensive fishing in the past, when it was the "right" whale to hunt due to its thick layer of blubber, that it is no longer recoverable. 

According to the Massachusetts Center for Coastal Studies (CCS), which has conducted one of the longest studies of the endangered population, only 372 individuals remain.

Declining genetic strength, ship collisions, entanglement in fishing gear, climate change, and sound pollution have weakened them to the point where they have been declared "functionally extinct" in the Eastern Atlantic, while the population in the Western Atlantic is "not recovering.

Longevity is critical for species that produce a small number of young. So human-caused mortality - once by hunting, now by marine fishing - is shortening the natural lifespan and reproductive period of whales to the point where they are at risk of extinction,

Polar explorers show how whales jump in AntarcticaApr 28 2024, 04:30 AM • 26468 views