On the way to work and on the way home. We unpack the issues drawing attention online and offline, going beyond the facts to the economic value and social meaning behind them. Every issue in the world, unpacked!
A shark nicknamed "Bukangi" has now spent 13 days in an artificial channel at Busan's North Port waterfront park, holding public attention. Some say authorities should simply wait until the shark swims out to sea on its own, but experts warn it must be returned to open water before water temperatures drop.
The city of Busan said on the 30th that 23,000 people visited the waterfront park the previous day, when a rescue operation was under way. From Sept. 18, when the shark was first spotted, through Sept. 29, cumulative visitors reached 639,000. Onlookers watched the operation and cheered for the shark to make it back to sea safely.
On Sept. 29, the coast guard and fire authorities deployed five boats and used water pumps to shoot jets of water from inside the channel, trying to drive the shark toward the exit. The shark dodged the jets by diving to deeper water or swimming tight against the channel wall.
When the operation failed to go as planned, some residents suggested it might be better to wait for the shark to leave on its own rather than force it out. Experts, however, say leaving the animal in the artificial channel for an extended period could be dangerous.
A narrow channel is no place for a shark
The channel where the shark is staying is 1.5 kilometers long and 30 to 60 meters wide. Depth ranges from 2.5 meters to 4 meters depending on the tide. Because the environment differs sharply from the open sea where sharks live, experts say a long stay could damage the animal's health or kill it.
Choi Yoon, an honorary professor of marine biology at Kunsan National University, said the channel is shallow, so its temperature falls quickly. "Bukangi's movements will slow down and it may become unable to feed," he said.
Once surface water temperatures fall below 20 degrees Celsius, conditions can become unsuitable for sharks. With temperatures forecast to drop sharply across the country starting Oct. 1, attention is also turning to changes in water temperature.
The shark is believed to have entered the waterfront park channel while chasing prey. Experts think it cannot find the way out because both ends of the channel bend.
If the water in the channel cools, temperatures are likely to fall first on the landward side while the seaward side stays relatively warm. The shark could move toward warmer water and find its way out to sea naturally, but experts say waiting for that outcome carries the risk that it dies.
Choi said he sees the chances of the shark leaving the channel on its own and the chances of it dying as "about even."
Feeding is another concern. Fish that could serve as prey, including mullet, live in the channel, but the shark has not been observed catching any so far.
Ji Hwan-seong, a researcher at the National Institute of Fisheries Science, said the species the shark is believed to belong to, the dusky shark, feeds in deep water. "It is difficult for that kind of wild animal to live in a narrow channel for a long time," he said.
He added that a shark can survive about two weeks without food but cannot survive if water temperatures fall.
Others warned against letting a wild animal grow accustomed to an artificial environment. Lee Chung-il, a professor of marine ecology and environment at Kangwon National University, said any wild animal that becomes used to an artificial setting has trouble returning to the wild. "It is right to get it out of the channel before it is too late," he said.
The coast guard and fire authorities plan a second rescue attempt on Oct. 2. This time they will install a large net specially made by the National Institute of Fisheries Science across the channel and pull it slowly toward the sea to keep the shark from moving back inland.
Once the shark is confirmed to have moved out to sea, authorities plan to block the channel entrance to prevent it from returning.
A shark in Busan, and climate change
As the shark draws nationwide attention, some say the episode points to shifts in the marine ecosystem driven by climate change. A large shark entering a channel in a seaside park is highly unusual, they say, and can be read as a signal of change in the marine environment.
The National Institute of Fisheries Science said on the 30th that 73 large sharks were caught incidentally off the east coast from the start of this year through the end of last month, 2.5 times the 29 recorded in the same period a year earlier. Incidental catch refers to sharks caught in nets set for other fish.
By species, shortfin mako accounted for the most at 37 cases, followed by salmon shark and blue shark with 10 each, and dusky shark and hammerhead with five each. Bukangi is also believed to be a dusky shark.
Large sharks do not have any particular adverse effect on coastal fisheries, but they can harm people, so caution is needed during marine leisure activities.
Rising water temperatures are seen as a factor behind the increase in large shark sightings off the east coast. Kim Maeng-jin, a researcher at the National Institute of Fisheries Science, said warming in the East Sea has expanded the range of warm-water species, making large shark appearances more frequent. "This trend could continue," he said.
