According to a new study, two particular whale species have been genetically affected by the whale hunting era back in the 20th century.
Whale Hunting Effects on Species' Genetic Diversity
Commercial whaling involved whale slaughter across the globe for the species' meat and oil. Because of this, several populations have been wiped out while several species were left close to extinction.
A new study has shown that the progeny of whale survivors are still affected by the grim effects of whale hunting. This was discovered by researchers as they examined bones of whales found on beaches close to abandoned stations for whaling in South Georgia Island within the South Atlantic Ocean. Some of these bones are over a century in age. However, they were able to remain preserved due to the cold tundra climate of South Georgia.
The researchers then compared the old bone DNA with whales that are alive today. They specifically focused on three South Atlantic species, namely, the humpback, fin, and blue whales.
The results of their study show that whaling from the previous century significantly and particularly affected both humpback whales (Megaptera novaeangliae) and blue whales (Balaenoptera musculus). Both of these species appeared to have lost their full maternal DNA lineages.
Angela Sremba, a marine ecologist from the Marine Mammal Institute of Oregon State University and the study's first author, explains that a maternal lineage is typically linked to the cultural memories of an animal that are passed down across generations. These memories may include breeding or feeding locations. Given the loss of maternal lineage, this knowledge is also likely to be lost.
Marine biologist Scott Baker from the Marine Mammal Institute explains that for the last 60 years, whales have not been present in the feeding grounds of South Georgia. This suggests the loss of cultural memory.
Baker adds that the number of whales that are going back to this area today is not big. However, they could be rediscovering the area.
The study also revealed that modern fin (Balaenoptera physalus), humpback, and blue whales in these areas still have quite remarkable genetic diversity. This shows relative optimism regarding general recovery.
The majority of whales who remain alive today are likely to be descendants of these whales who faced human onslaught.
Any 20th century whale survivors could be nearing the end of their life. As they die, it may entail even greater loss of maternal DNA lineages.
Sremba explains that it is urgent to conduct studies like this as specialists still have the fleeting chance to document the genetic information carried by these older whales who are still alive today.
Whale Hunting and Recovery
During the early 20th century when whale populations started to plummet in other areas, whalers kept on targeting the Southern Hemisphere. They established whaling stations in areas like South Georgia.
From the century's turn to the 1960s over 2 million whales in the Southern Hemisphere were killed. This number included roughly 175,000 from South Georgia's proximate vicinity. During this time, several whaling stations were hosted on the island.
While some South Atlantic whale populations are now reaching recovery, several still lie below the projected numbers before this whaling era.
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