Researchers have noted a decline in sharks in the Gansbaai coast area since 2017. This comes as two orcas have killed at least EIGHT Great White Sharks.
THE TWO ORCAS TRIGGER THE FLIGHT RESPONSE TO FEAR IN SHARKS
According to a study published in the African Journal of Marine Science, the shark carcasses washed up without their livers and hearts or with other injuries distinctive to the orca pair.
Shark experts at the Dyer Island Conservation Trust suggested the orcas trigger the ‘flight’ response to fear in sharks when nearby.
The report furthermore states that this, in turn, results in their rapid, long-term emigration from the area, creating an opportunity for an influx of new predators to deplete other species.
14 SHARKS WAS TRACKED FLEEING THE AREA WHEN ORCAS ARE PRESENT
“The research is particularly important, as by determining how large marine predators respond to risk, we can understand the dynamics of coexistence with other predator communities.
“These dynamics may also dictate the interactions between competitors or intra-guild predator-prey relationship.”Senior White Shark biologist Alison Towner
In a study published today in the African Journal of Marine Science, Towner reports that she has tracked 14 sharks fleeing the areas when orcas are present over a five-and-a-half-year period.
This accompanied a dramatic decrease in visual sightings in certain Western Cape Bays, where they have dominated over many years.
THE LOSS OF TOP PREDATORS COULD DISRUPT ECOSYSTEMS
The study warned that the loss of top predators could disrupt ecosystems and trigger trophic cascades.
“Predator–prey interactions between white sharks, other coastal sharks, and killer whales are increasing in South Africa and are expected to have pronounced impacts on the ecosystem.”The Study
The Dyer Island Conservation Trust On Monday, the 20 June, said a white shark was reported in from the Die Dam area of Overberg.
“The shark was retrieved by the Marine Dynamics Academy team (MDA) where the 2.94m specimen was then transported back to the International Volunteer lodge. Morning of June 22, photogrammetry and measurements were taken by Aline Pryazkhina and Ettiene Roets with the MDA volunteers. The shark appeared to have killer whale tooth impressions and a tear injury at the pectoral fin. The examination of this shark is similar to the previous sharks that have been predated by Orcas.”
Meanwhile, earlier this week a man was killed by a shark in Plettenberg Bay.
FATAL SHARK ATTACK IN PLETTENBERG BAY EARLIER THIS WEEK
The National Sea Rescue Institute (NSRI) spokesperson Craig Lambinon said the Plettenberg Bay duty crew was activated following eye-witness reports of a shark incident involving a swimmer at Sanctuary Beach, on the Robberg side of Robberg 5, Plettenberg Bay.
“Sadly, injuries sustained are fatal, and the man was declared deceased by the doctor.
“The family of the deceased man is in the care of Police and counsellors. Condolences are conveyed to the family of the deceased man.”Craig Lambinon