The first victim washed up in September 2016. Police in Valencia, Spain, saw a blue shark dying in the surf along a tiny stretch of beach. They lugged the 8-foot corpse to the yard behind the police station. Then they called Jaime Penadés-Suay, who soon suspected foul play.
The shark had what looked like a bit of wood embedded in her head. He pulled. Out slid a broken fragment from a swordfish sword that had lanced straight through her brain.
“I thought it was crazy,” said Penadés-Suay, a graduate student at the University of Valencia and a founder of LAMNA, a Spanish consortium that studies sharks.
But since then at least six more sharks have washed up on Mediterranean coasts, each impaled with the same murder weapon and almost always in the head. In the latest example, an adult 15-foot thresher shark washed up in Libya. Inside was a foot of swordfish sword that had broken off near its heart.
Taken together these cases offer what may be preliminary scientific evidence of high-speed, high-stakes underwater duels that had previously been confined to fisherman’s tales.
When sharks die, their bodies typically sink to the bottom of the sea. So a published record of half a dozen stranded sharks with suspiciously precise wounds could indicate that these encounters are common — and that a swordfish sword is sometimes exactly what it sounds like.
“Now at least we have evidence that they might use it really as a weapon, intentionally,” said Patrick Jambura, a graduate student at the University of Vienna.
Jambura led a study of the recent dead thresher shark, which turned up this April.
Most victims of swordfish stabbings in the Mediterranean have been blue or mako sharks. Both of those species prey on young swordfish, suggesting one explanation: Maybe juvenile swordfish had felt like their lives were threatened and fought back.
But this time the sword fragment looked as if it had come from an adult swordfish, which typically are not eaten by a thresher shark.
Instead, Jambura and his team argue, the swordfish might have been taking out an ecological rival.
Penadés-Suay doubts competition would be enough of a motive given the risks involved in taking on a big, whip-tailed shark. Instead, he thinks, the swordfish might have felt attacked and tried to protect its territory.
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