Bukangi: Will the shark leave the Busan canal and make it back to sea?

As soon as a large shark was spotted in a canal in Busan, a bustling shipping hub and beach city on South Korea's south-eastern tip, marine biologist Kim Hyun-woo was drafted in to rescue it. He got the call in mid-September, on his way home from a business trip tracking shoals of mackerel to aid fishing vessels. Despite being one of the country's leading shark experts, he never thought he'd be asked by the coastguard to actually save one.

South Korea is no stranger to sharks but one this size, in a shallow, concrete canal right by the world's seventh busiest port, was unheard of - until now. With an excited crowd already gathering at the waterfront, his team from the National Institute of Fisheries Science had to move fast.

The first task was to determine the species. Some sharks are more dangerous than others. The star of the 1975 blockbuster Jaws, the great white shark, is known to attack and kill humans. The specimen in Busan was found to be a female dusky shark, a species linked only to two deadly attacks. Still, Kim feared someone in the crowd might jump or fall into the canal.

The shark had to return to sea. A small coastguard ship made an initial attempt using an electrical deterrence device, which generates a weak current that sharks avoid. They're usually used after sightings near popular beaches. But after five hours, officials determined this particular shark was too large and fast for the device.

Kim changed tack, deciding instead to wait for the shark to let herself out. But that did not happen. As authorities looked for ways to guide her out of the canal, the stranded creature went viral. Just hours after she appeared, the council had sent everyone in the city an emergency text alert, urging pedestrians and residents to 'exercise caution for their safety'.