Shrinking size of whales can signal impending population collapse

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Shrinking size of whales can signal impending population collapse

June 23, 2017 - 20:31
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Scientists studying historic whaling records discovered that there had been specific signs that foretold the worldwide collapse of commercially harvested whales up to 40 years before it happened.

Sperm whales.

Research data from the past has revealed that one of the signs of impending global collapse of the population of whales is the shrinking sizes of the whales.

The scientists, from the University of Tasmania's Institute for Marine and Antarctic Studies (IMAS), and the University of Zurich, studied records from the International Whaling Committee (IWC) on the abundance and body size of four whale species (blue, fin, sei and sperm whales) before the 1985 commercial whaling moratorium.

Lead author Dr Chris Clements from the University of Zurich said, “Our study of IWC catch records showed there was a dramatic decline in the average body size of whales last century, detectable up to 40 years before the global population collapse.”

“We […] found significant declines in body size, with sperm whales taken in the 1980s four metres shorter on average than those taken in 1905,” he added.

According to IMAS co-author Associate Professor Julia Blanchard, “In the face of global environmental change, it's important that we can predict which species are at risk so appropriate conservation measures can be taken."

The research also has the potential to be applied to other species to highlight early warning signs of a species’ impending collapse.

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