Since 2010, killer whales have been responsible for the murder and subsequent consumption of the livers of sharks

Since 2015, two killer orcas known as Port and Starboard have been responsible for the deaths of at least eight great white sharks.

 

Killer whales are being slaughtered at an alarming rate in the waters off the coast of South Africa.

 

Since 2017, a pair of male orcas (Orcinus orca) have been responsible for the massacre of at least eight great white sharks (Carcharodon carcharias) off the coast of Gansbaai. These orcas have torn the terrible animals apart and consumed their livers in all but one of the cases. Some of the sharks even lacked their hearts when scientists found them dead and torn on beaches in the area. These sharks are found occasionally by experts.

 

Orcas are known to kill a wide variety of prey, ranging from the tiniest fish to the giant sharks, sea lions, and even blue whales, so it is not surprising to see them engage in such gory displays. The authors of a new study that was published on Wednesday (June 29) in the African Journal of Marine Science claim that the violent escapades of two individual whales have rarely had such a clear and immediate influence on their habitat. However, this was one of those rare occasions.

 

According to the findings of the experts, the number of sightings of great white sharks in the region has significantly decreased ever since the two serial killer cetaceans started their killing spree five years ago. The researchers observed that dozens of sharks actively avoid sections of the Gansbaai coast when orcas are nearby by using a combination of long-term sightings and data from tagging. The researchers used the data from the tagging to support their findings. Tagged sharks have been known to vanish for weeks or even months at a time, abandoning areas that great white sharks have traditionally dominated throughout history.

 

"What we seem to be witnessing, though, is a large-scale avoidance strategy," Alison Towner, a senior biologist studying white sharks at the Dyer Island Conservation Trust in South Africa, said in a statement. Towner is the lead study author and studies white sharks at the Dyer Island Conservation Trust in South Africa. Wild dogs in Tanzania's Serengeti are known to use a similar strategy in response to an increased presence of lions. "The longer the great white sharks stay away from these areas, the more frequently the orcas visit these spots,"

 

Killer whales that kill repeatedly

 

About 120 kilometres (75 miles) to the east of Cape Town is where you'll find Gansbaai. The authors of the study state that because great white sharks are present in the region throughout the year, Gansbaai has become a popular tourist attraction for people who want to observe sharks.

 

Great white sharks can grow to be as long as 16 feet (4.9 meters) in length and have as many as 300 serrated, knife-like teeth. They are one of the most formidable predators that live in or frequent the ocean. But beginning in 2015, a pair of mature male orcas arrived in the area, and they proved to be more than a match for the sharks that lived in Gansbaai.

 

The orcas were immediately identified by the battle scars on their bodies, much like cartoon felons. The dorsal fin of one whale had crumpled to the right, while the dorsal fin of the second whale was twisted to the left. Because of these characteristics, local whale watchers have given the orcas the nicknames "Port and Starboard." A great white shark washed up dead on the shore not long after whale watchers at Gansbaai noticed the pair swimming together in the area.

 

Between the years 2016 and 2017, the remains of five additional white sharks were discovered, with four of the deceased having had their bodies torn apart and their livers removed. According to recent research by Live Science, sharks have a vast and fatty liver, which might give a great deal of energy and nutrients to predators. The deaths of each shark were found to be correlated with the presence of port and starboard in the vicinity. Even though they only claim to have killed eight sharks, there may be additional shark carcasses that have been lost at sea.

 

In the six months that followed the death of the first shark in Gansbaai, the number of daily shark sightings dropped from around six sightings per day to just one sighting per day. A decrease was also seen in the number of sharks that were detected that had been tagged with electronic transmitters. Before the assaults in 2017, tagged sharks ranging from three to eight were found in the region daily. For a few more months, that figure remained at zero. The data from the transmitters showed that individual sharks occasionally travelled several hundred miles away from Gansbaai within only a few days of being attacked by orcas. In some instances, sharks avoided the area for at least half a year before making their way back.

 

According to the findings of the researchers, this massive migration of sharks has had repercussions on the environment in the area. The most notable change is the introduction of a new species of mid-level predator, the bronze whaler shark (Carcharhinus brachyurus), which has relocated into the region to fulfil the role that great whites used to play. According to the findings of the researchers, the number of sightings of bronze whalers has dramatically increased since the disappearance of great white sharks, which are common predators of these sharks. The scientists noted that this change might cause a chain reaction throughout the entire food chain, which would impose stress on the whole ecosystem.

 

Where did all of these killer whale attacks come from in the first place? Orcas, as vicious as they are, do not usually hunt great white sharks, according to the researchers. However, scientists have identified a rare subspecies of killer whale in South Africa that has flat teeth and appears to specialize in hunting sharks. According to what was written by the team, it's probable that Port and Starboard are part of this organization. According to Towner, the unexpected sighting of orcas in Gansbaai may be "due to a drop in prey stocks, particularly fishes and sharks, prompting changes in their distribution pattern."

 

Additional research into the whales and sharks of Gansbaai is required if this marine homicide case is going to be solved in its entirety.

Article source : https://www.livescience.com/killer-whale-great-white-shark-killing-spree

Image source  : https://pixabay.com/id/photos/laut-paus-bungkuk-ekor-air-2052650/

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