Humpback whale migration starts early
Durban - The annual humpback whale migration appears to have started early off the eastern coastline this year, the KwaZulu-Natal Sharks Board said on Wednesday.
"Scientists both in New Zealand and Australia have also recorded the early movement of these cetaceans," said the board's head of operations, Mike Anderson-Reade.
Humpback whales leave their feeding grounds in Antarctica to migrate to warmer waters to mate and give birth every year.
They move away from icy waters to the east coast of SA and Mozambique and arrive around May. Pregnant females will give birth in warm waters and then nurture their calves for a few months before leaving the area.
According to the oceania.org website this was because at birth humpback whale calves have little body fat and would not survive in the icy waters of the Antarctic.
"The calves grow up here before they go back to Antarctica. They leave our waters around October, November and December," said Anderson-Reade.
"Normally we see these whales arriving here in May, but this year we have already seen the animals in the past few weeks."
A whale carcass was seen floating offshore in Amanzimtoti early last week. Later 14 tiger sharks got caught in shark nets at Scottburgh beach, a short distance away on the KwaZulu-Natal south coast.
"The carcasses of these whales are notorious for attracting large [great] white and tiger sharks," Anderson-Reade said.
"Should these carcasses drift close inshore, the sharks that are scavenging on them may present a threat to bathers and surfers."
The board said with the increase in number of the humpback whales "in our waters", it was inevitable that their mortality rate would increase naturally and through other causes. These included being hit by ships or killed by sharks.
He said it was possible that some humpback whales might move down toward the Western and Southern Cape coastline.
On April 14, the carcass of a 14m-long whale washed up on the rocks at Buffels Bay. A day later the National Sea Rescue Institute issued a shark warning.
"[Bathers are urged] to exercise caution following reports of increased shark activity in the vicinity of Buffels Bay and Knysna, following the beaching of a... whale carcass," spokesperson Craig Lambinon said at the time. He said fishermen and boaters had informed the institute of an increase in shark activity.
On April 19, a great white shark attacked and killed champion body boarder David Lilienfeld at Kogel Bay. The beach has since been closed.
Meanwhile, whale carcasses washing onto beaches remained a "considerable" removal problem for local authorities, said Anderson-Reade.
"If the KZNSB is informed timeously of the accurate position of a drifting carcass, attempts may be made, in the interests of public safety, to tow the carcass offshore into the current and away from the coast," he said.
"This will also obviate potentially high catches of sharks in the shark nets, as was the case last week."
The board appealed to the public to contact it on 031 566 0400 to report dead whales floating between Richards Bay and Port Edward.