Mass dolphin death
Beaching leaves experts puzzled
10 March 2020 | Disasters
It is a disaster for the black dolphin population off Africa’s west coast: A total of 86 dolphins were found dead on the beach about 60km north of Lüderitz.
“The scene was more than just sad,” said marine biologist Kolette Grobler.
She said that commercial crayfish fishermen made the discovery last Friday. The beach is located at the remote Hottentots Bay. “Because it sounded very unusual, we set off on Saturday morning with the fishery research ship Anixab,” Grobler said.
Once there, they counted a total of 86 dolphins – all in an advanced state of decay.
Grobler estimated that two dolphins were only a few days old. She assumes that the animals had already been beached between five and seven days before. “Because of the decay, we couldn’t take any samples from the carcasses. However, we did take water samples to check for possible toxins.”
Scientists have several theories about the beaching. Most likely is the assumption that a dolphin was either injured or sick and intentionally swam to the beach, and that the other dolphins followed to try and help.
This theory would be plausible, since 34 black dolphins were stranded in Shearwater Bay four years ago. Thirty-three dolphins were brought back into the water by senior marine biologist Jean-Paul Roux and some tourists. One dolphin did not survive the beaching. At that time it was very week, which probably triggered the stranding.
Dolphin expert Simon Elwen (of the Namibia Dolphin Project) has the same theory: “As with many other social animal species, black dolphins stick close to a sick or injured animal and can end up stranded themselves,” he told this newspaper.
Experts cited either seawater toxins or seismic activity as another possible cause. “They could also have been driven to the beach by a killer whale,” Elwen speculated.
Black dolphins are relatively small, but are known for their impressive aerial acrobatics. From land, they are rarely seen compared to other species, as they are usually in deep water. They occur in parts of South America, southern Africa, Australia, New Zealand and on several sub-Antarctic islands.