Thanks to some help from a quick-thinking ferry captain, a thresher shark has made a successful escape after becoming trapped in a UK harbour. Best known for their scythe-shaped tails, threshers tend to stay far offshore, where they hunt in deep water, so this sighting is quite out of the ordinary.

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It's thought the lone shark swam into Fishguard Harbour in Wales in pursuit of schooling fish, and wound up stuck between a local ferry, Stena Europe, and the nearby dock. Experienced captain Richard Davies killed the vessel's engines in the hope that the distressed animal would simply swim under the ship and back out to sea, but the shark couldn't find its way.

"When captain Davies realised the shark was trapped, he eased the bow of the Stena Europe away from the quay wall, which allowed it to escape!" says the team at Goodwick Sea Trust, noting that the animal swam away in seemingly good condition.

Thresher sharks are considered vulnerable to extinction by the IUCN, but they're relatively common in UK waters (earlier this year, a group of fishermen in England sacrificed an official size record to release a 368-pound (167kg) thresher back to the sea). However, the sharks' open-ocean diet is one reason why they're hard to spot – they tend to stay 40 to 50 miles offshore. Those weaponised tails allow the sharks to stun baitfish like anchovies, larger fish like herring, mackerel and salmon, as well as squid and other invertebrates. 

What's more, the sharks are mostly seen in these waters in the summer, which makes this harbour visit even more unusual. "A mate of mine has been here 30 years and had never seen a shark before!” Stena crew member Daniel Williams told Wales Online.

Juvenile threshers do show up in coastal waters, and it's possible this one came into the harbour in search of food. In any case, we're glad to see the shark managed to manoeuvre its way to safety!

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Top header image: Klaus Stiefel/Flickr