Monday, October 2

Scientists have discovered a refuge for orcas in the northern Pacific that dates back to 20,000 years ago.

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The North Pacific’s orcas are credited to SDU/Olga Filatova.

There are multiple populations of orcas in the northern Pacific near Japan and Russia. They do not communicate, have no commonalities between food sources, use different languages, and cannot mate. How can this be reconciled when they live so close to each other and belong to the same species?

Olga Filatova, a whale biologist from the University of Southern Denmark, is currently employed at the Marine Biological Research Center at university and is keen on exploring how orcas have colonized the northern Pacific. She spent her time studying whales in Moscow and conducting several expeditions to the area.

Her recent discoveries have been published in Marine Mammal Science. They examine the complex relationship between orca culture and the North Pacific’s colonization, revealing that the current orcas populations in Nemuro Strait, Japan, are descended from those that existed there during the last ice age. The area was chosen as a refugium by long-lost ancestors, and their descendants have persisted there since then.

According to Filatova, orcas are docile and stick to their established practices, which they do not change or alter unless there is a compelling reason.

She has come across an orca refugium from the Ice Age for the second time, with the first one located 2500 km away near the Aleutian Islands. The pods there are as traditional and conservative as their Japanese counterparts, and are also descendants of Ice age ancestors who found shelter in frozen waters.

When the ice began to retreat again and orcas and other whales could swim to new areas without an icy surface, they did not follow. They remain in their refugee status, as reported by Filatova.

The studies are based on genetic analyses, which involve skin biopsies and sound recordings recorded underwater using microphones.

According to Filatova, the orcas found in the Nemuro Strait had a high genetic diversity, which is typical of glacial refugia. Their vocal range is distinct from that of their dialects living northward along the Kamchatka coastline. She suggests that these orca populations are likely the descendants of small groups that migrated west from the central Aleutian refugium.

Orcas possess a wide range of vocalizations, and since no two pods produce identical sounds, they can be used to identify individual connections to families and pod members. Orca populations are not genetically programmed to produce sound, such as those found in cats. In contrast, orcas receive communication from their mother or other family members through meowing when opening their mouth.

Filatova points out that the combination of this with genetic analyses provides a robust understanding of how orca communities interact.

Two Ice Age refugia have been unearthed, providing insight into how orcas could adapt to current and future climate shifts: The orca species are expected to move northward as the ice melts, and this colonization may occur in small, individual families or pods rather than large waves.

The identification of the two Ice Age refugia not only provides insight into how orcas survived during the Ice age but also enables us to understand how they grouped together, even if they are not part of a single species.

According to Filatova, many people believe that orcas should be separated into multiple species. She agrees with this, but believes that breaking them down into subspecies is problematic because of their distinctness in determining their role in the food chain and quotas for fishermen.

Some orcas consume fish, herring, mackerel, and a particular type of salmon.

Whether a pod feeds on fish or not has pronounced implications for the nature of fishing in their habitat.A country’s calculation of its fishing quota must take into account the natural number of fish that are killed by predators, and since an animal can consume 50–100 kg of catch daily, it heavily impacts the calculation process.

If pods are unable to touch fish and consume marine mammals, it is crucial for them to be captured and sold to marine parks. However, Chinese marine park land still has a significant market for orcas.

Because of the limited scientific knowledge of orcas, scientists have utilized a distinct classification method to differentiate between various types of animals and divide them into ecotypes. In the northern Pacific, three ecosystems have been identified, while in the southern hemisphere, four or five have already been described.

Filatova believes that there could be up to 20 distinct ecotypes.

“We must be familiar with the diverse ecotypes. Orcas are at the top of the food chain, and their eating habits and habitats have an impact on everything in our environment,” she states.

The SDU Marine Biological Research Center in Skagerrak and Kattegat have observed the presence of orcas in their waters, but it is unclear whether they consume fish or other marine animals, which could impact the food chain and fishing activities.

Filatova hopes to gain more knowledge about them. Perhaps they are a new ecotype, she says.

Olga A. Filatova et al. have published findings in Marine Mammal Science (2023) that genetic and cultural evidence indicates the presence of a refugium for killer whales during the Last Glacial Maximum near Japan. The journal has 10.1111/mms.13046 as of 2023.

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