Fish experts have been unable to shed light on why scores of dead fish were seen in the sea near uShaka beach in Durban earlier this week.
Divers Selwyn Rautenbach and Carl Stow said they came across 20 to 30 dead fish, mainly shad, lying on the ocean floor, about 50m offshore, on Wednesday.
“We were going to dive at the wreck of the Ovington Court, but we didn’t stay in very long because the sea was dirty and smelly.
“The dead fish were lying in more or less a straight line, with their mouths and gills open. There were probably many more further along the backline, maybe a couple of hundred, but we cancelled our swim,” said Rautenbach.
Stow said he did not think the dead fish had been dumped by fishermen as there were no visible hook marks or other wounds.
Sean Fennessy, a fish scientist at the Oceanographic Research Institute in Durban, said he had not received similar reports from other residents and it was difficult to speculate on what might have killed the fish.
“It is possible that this is related to the recent sand pumping and dredging in the uShaka/harbour mouth area, because there has been quite a lot of activity here over the last few weeks.”
If this was the case, the fish might have been sucked up by dredgers and then floated out to sea.
However, after seeing video grabs of the dead fish, Fennessy said it was possible that they were undersized shad discarded by a ski boat crew before returning to shore. If there was a mix of species, they could have been discarded by seine netters.
“It really is difficult to know without inspecting the fish and gathering other evidence, but if we receive other reports like this we could look into it more closely,” he said.