A fisherman caught a “monster” shark – only to discover it had already been half-eaten by an even bigger predator.

The angler, who calls himself Trapman Bermagui, hooked the shortfin mako in the South Pacific Ocean off the coast of New South Wales, Australia.

But by the time he had hauled it on to his boat he was left with only the severed head with one fin attached. The head alone weighed about 100kg, he claimed.

“So this was all we got back of this monster mako,” he wrote on Facebook. “Unfortunately we didn’t see what ate it but must of been impressive!!”

“It was a crazy morning of shark fishing. Hoping to catch smaller sharks but just hooked big sharks that got eaten by bigger sharks again.”

Endangered sharks being served up in British fish and chip shops Show all 6 1 /6 Endangered sharks being served up in British fish and chip shops Endangered sharks being served up in British fish and chip shops Scalloped hammerhead shark Scalloped hammerhead shark fins were among those found being sold by an Asian food retailer in the UK. These sharks are endangered, and in parts of the Atlantic Ocean, their populations have declined by over 95% in the past 30 years. Istock/Janos Endangered sharks being served up in British fish and chip shops Spiny dogfish In the samples of takeaway fish and chips sampled, spiny dogfish made up 90% of those sold under the names huss, rock salmon and rock eel. Doug Costa, NOAA/SBNMS Endangered sharks being served up in British fish and chip shops Shortfin mako shark Another vulnerable species found in the dried shark fins tested in the British Asian wholefood retailer was the shortfin mako shark. Istock/Alessandro De Maddalena Endangered sharks being served up in British fish and chip shops Blue shark Blue shark was also found on sale in UK shops. This species is not as vulnerable as the others but is still listed as "Near Threatened" by the International Union for Conservation of Nature Istock/Howard Chen Endangered sharks being served up in British fish and chip shops Nursehound Around a quarter of the sharks being sold in UK fishmongers were nursehounds, another relatively safe species that is nevertheless classified as near threatened. Mario Antonio Pena Zapatería Endangered sharks being served up in British fish and chip shops Misleading names in fish shops The scientists behind the study investigating the prevalence of endangered shark meat on sale concluded that shops must stop selling these species under "umbrella terms" that hide their true origin. Istock

He also claimed that when his crew cut into the mako head they discovered the spear-like bill of a marlin embedded inside from a previous battle.

The post sparked dozens of suggestions about what might have eaten the mako, including Orcas, a great white or even a Megalodon, an extinct species of shark that existed millions of years ago.

One joked that the culprit could be a penguin or possibly a colony of penguins, adding: “What they lack in flight ability they make up for with ferocity. Me personally wouldn’t ever turn my back on a bird fish.”

Several people replied with the classic line from the movie Jaws: “We’re gonna need a bigger boat.”

Others were not so impressed, claiming that the fisherman had exaggerated the size of the shark head by using a false perspective for the photograph.

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The mako is considered the fastest shark in the world, reaching speeds of up to 43mph, and ranges in size from 2m (6.5ft) to 4m (13ft).