Record size bony fish found floating dead near Azores archipelago

A team of researchers affiliated with multiple institutions in Portugal, working with a colleague from New Zealand and another from Japan, has released a report detailing an extremely large ocean sunfish that was found floating near to Faial Island off Horta Harbor in the Azores archipelago, off the coast of Portugal. In their paper published in Journal of Fish Biology, the group describes features of the huge fish and its probable cause of death.

Back in December 2021, fishermen working off the coast of Faial Island came across the carcass of a large fish floating on the surface of the sea. Impressed by its size, they pulled it from the water and carried it back to shore. Once ashore, the fish was identified as a southern or bump-head sunfish. The fishermen then called the Atlantic Naturalist Association to report what they had found.

A team was assembled and traveled to the dock to have a look at the fish. Once there, the fish was measured and then dragged onto a scale and weighed—the researchers found it to be 3.59 meters long and it weighed 2,744 kilograms. That made it the heaviest bony fish ever recorded.

Sunfish resemble bloated dolphins with a large dorsal fin. The southern sunfish, which is also known as Ramsay's sunfish, live in many parts of the world. In addition to its huge size, the sunfish is also known for its odd habit of laying sideways on the surface of the sea, basking in the sun. It is thought the behavior helps the fish warm itself after diving deeply into cold water to catch prey. Sunfish normally eat jellyfish, but have also been seen noshing on squid, fish larvae, several kinds of crustaceans and assorted small fish.

The researchers also found that the fish had been injured—there was a large dent in its head—which was likely what led to its death. The team suggests it was likely due to a collision with a ship. They also cut the fish open to examine the contents of its stomach and to diagram its digestive tract.

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