This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Antarctic blue whales appear to be creeping back from the brink of extinction after 50 years of protection. A new study estimates the total population at 4,018, up from 418 after the last reported whale catch in 1973.
Still, their population pales in comparison to pre-whaling levels, when hundreds of thousands of blue whales swam in the Southern Ocean. Antarctic blue whales were the primary target of commercial whaling in the 20th century. Each whale can weigh more than 400,000 pounds (180,000 kilograms), making them the largest animals known on Earth and a profitable source of whale oil.
Killing them was banned by the International Whaling Commission in 1964, but illegal whaling by Soviet fleets continued for another 10 years. By the time it stopped, it was almost too late for the species. "No whale was hunted quite to the extent that Antarctic blue whales were hunted," said lead author Zoe Rand, a postdoctoral scholar in the UW School of Marine and Environmental Affairs.
"We brought together historical whaling data and contemporary abundance estimates to create a full picture of just how heavily people hunted them and how they are doing now." The results were published Nov. 5 in Endangered Species Research. Tracking whale populations helps researchers determine whether they are recovering from whaling, but counting whales is a challenge. Although large enough to spot from space, Antarctic blue whales spend limited time on the surface.
Researchers rely on a combination of photo identification and line transect surveys to estimate the total population. Line transect surveying involves traveling in a straight line and counting animals sighted en route. In this case, a ship sails along an axis looking for whales.
The number of sightings and distance from the boat can be used to calculate density, and therefore abundance. However, these methods are imperfect and expensive. The International Whaling Commission surveyed the entire Southern Ocean in expeditions from 1978 to 1984, 1985 to 1991 and 1991 to 2004.
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