A dusky shark that became a national sensation in South Korea has returned to a canal in the port city of Busan, just hours after a lengthy rescue operation guided it back toward open water.

The shark, nicknamed Bukangi, was first spotted swimming in the canal last month and quickly drew widespread public attention. Over the following weeks, rescuers made multiple failed attempts to guide it back to the sea using large nets.

On Wednesday, a livestreamed operation lasting more than eight hours saw rescue workers carefully guide the three-metre-long shark through the canal toward open water in a nearby harbour. Hundreds of fans gathered at a park overlooking the canal, cheering and waving goodbye.

By Thursday morning, however, Bukangi had reportedly swum back into the canal, breaking through a barrier installed by authorities to prevent its return.

The shark became briefly trapped in a tight space between two layers of nets. Rescuers freed it by removing the outer layer and subsequently reinforced the remaining barrier. Since then, authorities said, Bukangi has been swimming further out but continues to circle back toward the mouth of the waterway.

A government official said on Thursday afternoon that rescuers had concluded their operations to free the shark.

In the month Bukangi spent in the canal, it attracted more than 1.6 million visitors and gave a significant boost to Busan's tourism. The city embraced the shark as an unofficial mascot.

Authorities had grown concerned about Bukangi's well-being. The shark appeared to be injured and was not eating. Videos circulating on social media showed it swimming with what appeared to be a bloodied snout. Officials also warned that falling water temperatures could weaken it further.

Experts believe Bukangi may have been drawn to the canal by unusually warm waters and an abundance of fish. With sea temperatures rising each year, they say Busan could see more sharks in the future.

The rescue prompted mixed reactions among residents and visitors. Some felt the shark should be allowed to remain in the canal, while others believed it was better off in the open sea.

Two people were seen holding cardboard signs protesting against Bukangi's removal. One of them, Cho Hannah, had travelled two hours from her home in North Gyeongsang province to see the shark.

"This shark has made this canal her home, and we are kicking her out unnecessarily. I am afraid the shark might die tangled with the net, or die out at sea," she said, calling Bukangi "a rare gift" to Busan.

Others expressed concern for the shark's health and supported the decision to return it to the sea.

"Bukangi seemed much larger when I first saw her on 18 September, when she first got here. Now she seems gaunt. I'm worried for her health if she stays," said Yoon In-taek.

Shin Seungmin said Bukangi had "brought so much joy to us" but that she belonged in the wild.

"It doesn't sit right with me that she keeps returning here. It will be best if Bukangi leaves, doesn't come back, and lives and feeds freely in the open sea. I'd love to see her find a healthy, free life out there," he said. "But she should go and live her normal shark life."