Orca moms may be feeding their sons into extinction

Orca moms may be feeding their sons into extinction

Subject : ENVIRONMENT

Section: BIODIVERSITY

Context: The study took place over nearly half-a-century and followed the lives of 40 female orca whales. The researchers wanted to understand why the species was becoming increasingly endangered.

More on the News:

• Researchers found that when female orca whales had sons their chances of giving birth to future offspring reduced by 50%. This remained the case throughout the mother’s lifetime and was not observed in orcas who gave birth to daughters.
• Killer whale mothers pay a high cost in terms of their future reproduction to keep their sons alive.
• It was along with these findings about the decreased reproduction rates that the researchers also noted how orca mothers continued a very close maternal relationship with their male offspring. The mothers gave their sons half the salmon they caught for themselves.
• That was not the case for the orca daughters, who were generally fed by their mothers until they reached their own reproductive age.
• There is an idea that this behavior — to ensure the young male ocas are fed and fit — could be an attempt by their mothers to increase the overall reproductive output of their population. Healthy males mate with many females, and that ultimately could increase the number of future offspring.
• This strategy of indefinitely sacrificing future reproduction to keep their sons alive may have been beneficial in their evolutionary past, but it now potentially threatens the future viability of the southern resident killer whale population.

About killer whales (orca):

• Orcas belong to a highly evolved group of toothed whales under the suborder Cetacean and dolphin family and are widely distributed in temperate and tropical waters.
• They have long life spans and are highly social, feeding cooperatively, and with complex vocal behaviours.
• While most killer whale populations in other regions show high site fidelity and residence rates, resident populations are yet to be identified in the northern Indian Ocean.
• Given their highly social and curious behaviour, orcas often approach fishing vessels to assess if there is any fish in the net, or just to observe people on the vessel.
• In the wild, there are no instances of killer whales fatally attacking humans.