This 4-metre shark was filmed thrashing about in shallow waters at Coronation Beach, north of Perth.
According to BBC:
The Western Australia Department of Fisheries said in a statement that it found "no visible signs of injury or disease" but discovered "a large Australian sea lion" in its throat.
Tash Tapper, who shot footage of the shark on the beach, said the whole scene was "surreal".
Research scientist Rory McAuley said: "Such a large object may have damaged the shark's internal organs or impeded water flow into his gills, contributing to his death."
This post has been corrected to properly credit BBC.