2023-10-09 10:22:01
Whale bones like those used for the study – SCOTT BAKER, MARINE MAMMAL INSTITUTE
MADRID, 9 Oct. (EUROPA PRESS) –
Commercial whaling in the 20th century decimated populations but also appears to have had a lasting impact in the genetic diversity of today’s surviving whales.
Researchers at Oregon State University compared DNA from a collection of whale bones found on beaches near abandoned whaling stations on South Georgia Island, in the South Atlantic Ocean, using whale DNA from the current population and found strong evidence for the loss of maternal DNA lineages among blue and humpback whales.
“A maternal lineage is often associated with an animal’s cultural memories, such as feeding and breeding locations, that are passed on from one generation to the next,” he said. it’s a statement the study’s lead author, Angela Sremba, who conducted the research as part of her doctoral studies at the Marine Mammal Institute. “If a maternal lineage is lost, that knowledge is likely to be lost as well.”
The findings were recently published in the Journal of Heredity.
South Georgia is a remote island about 1,200 kilometers southeast of the Falkland Islands and is home to several whaling stations that operated from the turn of the century until the 1960s. In just over 60 years, more than 2 million whales were killed in throughout the southern hemisphere, of which 175,000 were killed near South Georgia.
There is still evidence of that slaughter on the island, which is littered with thousands of whale bones (many of them 100 years old or older) that were discarded during commercial processing. The cold temperatures in the region helped its preservation.
South Atlantic whale populations have begun to recover since commercial whaling stopped, but whale sightings around South Georgia remain low. This suggests that local populations may have been extirpated, a term to describe a type of localized extinction, said study co-author Scott Baker, associate director of OSU’s Marine Mammal Institute. Baker last visited South Georgia Island as part of a research trip in early 2020.
“For 60 years, whales have been absent from South Georgia feeding grounds, suggesting that cultural memory was lost,” said Baker, who was Sremba’s Ph.D. tutor. “The number of whales returning to this region today is still not large, but there is a feeling that they may be rediscovering this habitat.”
To better understand how whaling may have impacted the genetic diversity of the current population, Sremba analyzed DNA extracted from bones found on South Georgia Island and compared the genetic information to previously published data from living whales in the later contemporary population. to whaling.
She and her colleagues identified bones from humpback, blue, and fin whales, and found that while genetic diversity among whales remains high, There are indications of a loss of maternal DNA lineages in the blue and humpback populations.
The researchers were unable to detect differences in diversity between DNA samples from southern hemisphere fin whales before and after whaling, likely due to the limited availability of post-whaling samples.
Because some species of whale can live up to 100 years, there is also a possibility that some of today’s whales were alive during the whaling era, Sremba said.
As these whales die, that could result in further loss of additional maternal lineages. This underscores the importance of preserving whale genetic information now, he said.
“It is surprising that these species have survived. In another 100 years, we don’t know what might change, and we can’t measure any change now if we don’t have a good understanding of the past,” Sremba said. “This work provides an opportunity to reconstruct the history of these whale populations and help us understand what was really lost due to whaling activities.”
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