Shark survives after being stabbed in the head by swordfish

A blue shark was skewered in the head by a swordfish, but survived to tell its tale in the first known case of a shark surviving this type of impalement.

When the shark was caught by fishermen in Vlorë, southern Albania, it showed no new puncture wounds and it had bait in its stomach, indicating it was feeding normally. An autopsy later revealed an 18.6-centimeter swordfish bill fragment embedded in his skull.

“When I realized that there was a swordfish beak inside the shark’s head, I was amazed,” says Andrej Gajić from the Sharklab ADRIA research center in Vlorë.

Gajić has performed tens of thousands of shark autopsies. “I’ve never encountered anything like this before and I’ve never heard of it in literature,” he says. His team tries to resuscitate and release accidentally captured sharks if possible, but this shark died before arriving at port.

There have been eight previously documented cases of blue sharks (Prionace glauca) impaled by the swordfish (Xiphias gladius) with the swordfish’s rostrum found in or near the shark’s head. A big-eyed thresher shark (Alopias superciliosus) and a short-finned mako shark (Isurus oxyrinchus) have also been found gored by billfish, the group that includes swordfish.

This is the first verified survival of a shark in such an encounter. When it was impaled, the young swordfish likely reacted instinctively by raising its head and snapping its beak without damaging any of the shark’s vital structures, Gajić said.

The adult shark measured 275 centimeters and weighed 44 kilograms. Swordfish can measure up to around 455 centimeters and weigh up to 650 kilograms. There are reports of blue sharks feeding on swordfish, and both animals use aggressive hunting tactics to prey on dense schools of fish or squid.

Such impalements can occur when swordfish attempt to defend themselves against an attack by a blue shark, or during an accidental collision when both predators feed on the same prey. Gajić says more observations are needed to determine the cause.