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Evidence giant blue whale making comeback - Auckland University

Contributor:
Fuseworks Media
Fuseworks Media

The critically endangered blue whale is increasingly looking like one of conservation’s biggest success stories and the good news just keeps on coming.

In the first multi-year survey at South Georgia Island in the southwest Atlantic where hunting drove whales almost to extinction, an international team of scientists reports some whale populations may be close to full recovery while others show promising signs of a comeback.

University of Auckland whale researcher Dr Emma Carroll, who has co-led the survey with Dr Jen Jackson from the British Antarctic Survey (BAS), says the latest data from South Georgia shows protection of whales has worked.

"South Georgia has a similar latitude to New Zealand’s own sub-Antarctic islands and as with our own populations of southern right whale near the sub-Antarctic Auckland Islands, we knew populations were increasing but these latest results are fantastic," she says.

"It’s also particularly significant because whales were slaughtered in their tens of thousands at South Georgia and to see them return in such numbers is just an absolute thrill."

Surveying humpback, blue and southern right whales, leading scientists from around the world report humpbacks are now a common sight in coastal waters at South Georgia with 790 reported during 21 days of surveying this season.

A preliminary estimate suggests more than 20,000 humpbacks are now feeding there in the summer months before migrating to colder waters in the sub-Antarctic to breed.

The rare and critically endangered blue whale, the largest animal that has ever lived, was sighted just once during the first year of the survey, in 2018. This year blue whales were sighted or acoustically recorded 55 times.

"Continued protection and monitoring is required to see if this unprecedented number of blue whales sightings is a long-term trend, as we see in humpbacks," Dr Jackson says.

The southern right whale was not seen in 2019 although it was regularly sighted in 2018 and 2020. Dr Jackson says that may be because they preferred to feed elsewhere in 2019 but scientists will further analyse the data to better understand feeding behaviour.

Genetic monitoring work pioneered in New Zealand’s southern right whales, Tohorā, will also be used to understand how southern right whales feeding around South Georgia are connected to wintering grounds around South America.

"What is clear is that protection from whaling has worked with densities of humpbacks in particular similar to those of a century ago and we are thrilled to see them at South Georgia again," Dr Jackson says.

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