The Swordfish is a highly migratory (pelagic) species found in tropical and warm waters all across the globe. They are also found on a large percentage of seafood restaurant menus across the United States which I find interesting because despite the fact that Swordfish as a species is a household name they’re an extremely deep water fish and we rarely if ever see them in our lifetimes unless it’s while reeling them up from the deep. I’ve been fishing my entire dang life and I’ve never seen one nor hooked one.
Scientists will occasionally happen across Swordfish on deepwater expeditions but it’s not a fish you’re likely to ever see swimming around in the bay unless it’s lost or sick. Unlike shallow-water fish that are easily observed, we don’t really see what the Swordfish does with the vast majority of its life which is why we’re only just now learning that Swordfish stab sharks in the head and murder them.
The broad pointed bill at the tip of the Swordfish is its iconic feature. I’ve seen videos of Sailfish using their bill to ‘slap’ baitfish and knock them unconscious so they can easily feed on them. What I’ve never seen is a Swordfish stab a frickin’ shark. There have been unconfirmed rumors for years that Swordfish use their bills to stab sharks and kill them…unconfirmed until now.
A shark washed up on a Mediterranean beach in Valencia, Spain back in 2016 with what appeared to be a piece of wood in its head, and this continued to happen periodically for several years with the same ‘murder weapon’ in the dead shark’s head each time. Now, scientists have been able to determine that it wasn’t wood but a piece of a Swordfish bill and these fish are stabbing and killing the sharks. The New York Times just published recent research on this which confirms the old fisherman’s tale:
Historically, whalers, fishermen and scholars saw swordfish as stab-happy gladiators. But modern scientists were skeptical. Sure, swordfish sometimes impale boats, whales, submarines and sea turtles. But perhaps these swordfish had aimed for smaller prey, and rammed something else by mistake.
Or maybe not. 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.
Mr. Jambura led a study of the recent dead thresher shark, which turned up this April. Sara Al Mabruk at Omar Al-Mukhtar University in Libya had spotted a video posted by local citizen scientists. In the video, a man approaches a shark on the beach, then pulls a sword from its back like a bizarre twist on Arthurian legend. “I was like, ‘Oh come on Sara, we have to do something about this. That’s just incredible,’” Mr. Jambura said. (via NYT)
Here’s that dead shark that was stabbed/impaled by a Swordfish, one of many over the past few years that has been killed by a Swordfish:
The team’s findings were published in the Journal of Ichthyological Research and now that we’ve confirmed that Swordfish are stabbing sharks the question becomes ‘why?’ because their bills are mangled and they don’t grow back. It’s not uncommon for a fisherman to reel in a Swordfish with a busted bill but why would the fish risk its sword if it won’t grow back? Here’s what the NYT article has to say about that:
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, they argue, the swordfish might have been taking out an ecological rival. In the overfished Mediterranean, the swordfish might have fought to ensure a larger share of the remaining scraps.
Mr. 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.
Whether the swordfish were protecting themselves from a threat or fighting to dominate a food source, the study provides evidence that they stab sharks with their swords intentionally https://t.co/YEcyED6SH9
— NYT Science (@NYTScience) October 27, 2020
So the short answer is ‘to win a fight’ and the long answer is ‘lots of reasons’. Because these fish hang out in depths up to 7,300-feet and are regularly found around 1,800-feet deep there’s really not much that can be said for certain about why an individual Swordfish stabbed a shark in the head and killed it. But we can now say for certain that Swordfish to use their swords to stab sharks, something that hasn’t been definitively proven until recently.
If you want to burn one of your ‘free monthly articles’ from the New York Times I suggest reading the article in full because it’s pretty fascinating. Just follow that link to read more!