There have been numerous reports about sharks missing their liver. According to reports, the culprits are orcas. Last month two orcas went on a shark-killing spree, so Newsweek spoke with a marine biologist to look into this matter.
Why Orcas Attack Great White Sharks
Andrew Trites, a professor and director of the Marine Mammal Research Unit at the Institute for the Oceans and Fisheries at the University of British Colombia spoke with Newsweek about the orcas or killer whales' behavior. According to him, there are different populations of killer whales with specialized diets. He noted that only a few are ecotypes or specialize in eating sharks.
For instance, in British Colombia, there is an ecotype that specializes in eating sharks, and two other populations specialize in eating fish or marine mammals.
As for killer whales targeting sharks' livers, Trites said it was because the latter's livers are full of oil and full of calories. Sharks have large livers with lots of oils and vitamins, making them appealing to killer whales as it could help them sustain their high calorific food requirement to maintain their energetically expensive lifestyle.
The expert noted that the sharks' livers help them maintain buoyancy because sharks lack swim bladders like most fish. Sharks' livers account for five to 10 percent of their weight, which is over the top compared to humans and other animals.
Killer Whales Attack Sharks
According to a study published in the African Journal of Marine Science in 2022, eight great white shark carcasses had washed up on beaches in the Western Cape near Gansbaai. Seven of the eight sharks had their livers torn out. There were also visible orca bites on their bodies.
In February, a pair of orcas massacred 17 sharks in 24 hours in South Africa. The Marine Dynamics academy has been tracking the orcas - Port and Starboard - since 2015 to know more about their hunting habits.
Every shark found had a missing liver. Experts were convinced that Port and Starboard feasted on the liver due to its abundant compound called squalene, a precursor for producing hormones, Daily Mail reported.
However, they don't extract the livers; they do so with surgical precision. The killer whale duo reportedly work together. They push sharks toward the surface and flip their belly before biting into their stomachs to extract the oil-rich liver while leaving the other organs intact.
Sharks are apex predators, and their absence due to killer whales going after them impacts the ecosystems. Alison Towner, a white shark biologist following Port and Starboard, previously told Newsweek that great white sharks have been avoiding the area to avoid being attacked by orcas.
However, balance is crucial in marine ecosystems, and with no great white sharks, seals can predate and critically endanger African penguins.
Towner said the impact of orcas removing the sharks in the area puts so much pressure on their environment.
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