First Killer Whales, Now Otters Are Feasting on Shark Livers Too

Otters in a South African coastal town have begun targeting sharks, eating their livers and hearts before discarding the rest of the body. The otters have also been consuming the male reproductive organs, a scientist studying their behavior said.

Over the last few months, several shark carcasses have been found by rangers working in the area around Simon's Town, which sits on False Bay—a body of water famous for great white sharks breaching the water surface while hunting.

The shyshark carcasses were photographed and some were kept so they could be examined by Alison Kock, a marine biologist at South African National Parks who also serves on the executive committee of the shark safety program Shark Spotters. "Based on these examinations, I discovered that the dead sharks had their hearts and livers missing, and in the case of males, the male reproductive organs (claspers) were also eaten. These are the most nutritious parts of the body," she told Newsweek in an email.

Kock said carnivores can be selective in the nutrients they take from prey, with preferences evolving to optimize their fitness. Other predators known to do this include bears, seals and killer whales, the latter of which have been making headlines in recent years for their attacks on sharks. In False Bay and the surrounding regions, there have been several cases of great white shark carcasses being found with their livers missing. Killer whales are believed to be responsible.

In the case of the Cape clawless otters, Kock said predators will often start getting more choosy about the nutrients they take from prey when food is abundant. The region where the otters are consuming shark hearts and livers is by the Table Mountain National Park marine protected area. "Shysharks are one of the most abundant species in the area," she said.

puffadder shyshark
The carcass of a puffadder shyshark that had been eaten by an otter. Alison Kock SANParks

"The carcasses were found around an otter den, and the bites were numerous and small in size—and very different to the bites I've seen made by killer whales on the sevengill, bronze whaler and white sharks. I noted that lots of 'nibbling' took place on the carcasses I examined."

Images of the otters feeding on shysharks were also captured by another scientist who was running a camera trap project in the area. The behavior was also recently filmed at Miller's Point, a protected stretch of coastline in Simon's Town.

"Most people think of sharks only as predators, but they are often prey to a variety of other animals," Kock said. "Most sharks are not apex predators, but what we call meso (middle) predators. It's only the largest sharks, like whites, tigers and bulls etc. which we consider apex or top-order predators, and even these are prey for killer whales."

This article has been updated to clarify the predators that perform nutrient-selective behavior.

otter
Stock image of an otter. Clawless otters in South Africa have been eating shark livers and hearts then discarding the rest of the body. iStock