March 21, 2023 at 08:22
Inbreeding is currently the biggest threat to killer whales on the North American west coast. The dolphins are sometimes so closely related that they die at a younger age. The already endangered species cannot recover in this way.
Female killer whales are most fertile at age 20. But often enough, they don’t even reach that age, according to a new study published Monday in the scientific journal Nature Ecology and Evolution.
According to the researchers, it is not necessarily inbreeding itself that makes the population so vulnerable. “It’s more that inbreeding makes the animals more vulnerable to disease and environmental factors,” co-researcher Kim Parsons told the AP news agency.
According to the researchers, there are three main groups of killer whales west of the US and Canada. Although the groups’ habitats overlap, they haven’t crossed regularly enough in the last 30 generations, the researchers said.
An orca performs a trick at a water park in the Chinese city of Shanghai. Photo: Getty Images
Catch for water parks dramatic for the killer whale
The orca population west of the United States and Canada has had a hard time over the past half century. Due to environmental pollution and the capture of killer whales for water parks, the species was threatened with extinction.
In the 1960s and 1970s, it was very common to catch killer whales for the entertainment of humans. According to the water parks, there were enough orcas in the sea and the animals could also be caught sustainably.
But at least thirteen orcas died during the catch. 45 orcas ended up in animal parks around the world. As a result, 40 percent of orcas off North America rapidly disappeared, the report said. Now catching killer whales is prohibited by law.
Situation not hopeless
Still, according to Parsons, the situation is not hopeless for the orca. According to her, people can help the species by creating the best possible habitat for the orca. That is already happening. In North America, for example, dikes have been breached and dams have been removed to make room for salmon, food for orcas.
There are also restrictions on fishing, so that there is still enough food left for orcas. And boats need to move slower and farther away from orcas, so the animals are less stressed and can hunt better.
Humans should not interfere with the orcas’ reproductive process, say the researchers. Certainly not by bringing the animals into contact with each other by catching them. “We really should leave it to the orcas to mate with whoever they want and support the population in other ways,” says Parsons.