Rescue workers use a specially made net to guide the shark known as Bukang-i out of the waterway at Bukhang Waterfront Park in Dong-gu, Busan, on Friday. [Yonhap]
Rescue workers use a specially made net to guide the shark known as Bukang-i out of the waterway at Bukhang Waterfront Park in Dong-gu, Busan, on Friday. [Yonhap]

The shark that has captivated the public by lingering for 19 days in an artificial waterway at Bukhang Waterfront Park in Busan has been confirmed as a bignose shark — a species classified as endangered due to declining population numbers.

The National Institute of Fisheries Science confirmed the identification Tuesday, according to Yonhap. The shark, nicknamed Bukang-i, has been in the waterway at the park since Sept. 18.

When Bukang-i first entered the waterway, the institute initially estimated it was either a bull shark or a bignose shark, both belonging to the genus Carcharhinus.

To determine the exact species, researchers analyzed close-up video footage. The analysis revealed a clearly developed interdorsal ridge — a raised line running between the first and second dorsal fins — a defining physical characteristic of the bignose shark.

The presence of an interdorsal ridge indicates a bignose shark, while its absence points to a bull shark. The two species are difficult to tell apart with the naked eye.

The bignose shark is a large species with a broad, rounded snout. Its upper jaw features triangular teeth with well-developed serrations.

Newborns measure about 70 to 100 centimeters in length, and the species can grow up to 4.2 meters.

It is widely distributed across tropical, subtropical and temperate coastal and offshore waters worldwide, including in Korean coastal seas, and tends to prefer water temperatures between 18 and 26 degrees Celsius.

Its diet consists mainly of fish and squid. No research has been conducted on the feeding habits of bignose sharks in the North Pacific, but those found off the coast of Australia are known to prey on mackerel, horse mackerel and sardines.

The bignose shark is viviparous, giving birth to live young. It grows and reproduces slowly. The International Union for Conservation of Nature lists it as endangered on its Red List due to population decline.

In South Korea, the bignose shark was once classified as the same species as the bull shark. It was not reported to the domestic scientific community as a previously unrecorded species until 2019.

Bukang-i measures about 3 meters in length. Examination of the shark's reproductive organs confirmed it is female.

Authorities weigh options as Bukang-i shows no sign of leaving

Rescue workers use a specially made net in an attempt to guide Bukang-i out of the waterway at Bukhang Waterfront Park in Dong-gu, Busan, on Friday. [Yonhap]
Rescue workers use a specially made net in an attempt to guide Bukang-i out of the waterway at Bukhang Waterfront Park in Dong-gu, Busan, on Friday. [Yonhap]

Meanwhile, authorities continue to deliberate over how to handle Bukang-i.

According to Busan city officials and other relevant authorities, Bukang-i was spotted Tuesday in its usual area — the waterway between the fourth and fifth pedestrian bridges — as it has been on most days.

On Friday, authorities used a specially made net to herd Bukang-i to a point about 100 meters from the waterway's exit, then fixed the net in place to prevent the shark from swimming back inside. But Bukang-i cleared the net and returned to the inner waterway the very next day.

Officials believe the shark seized the opportunity when high tide raised the water level enough to partially submerge the net.

The development dashed authorities' expectation that Bukang-i would swim around outside the net and eventually make its way back out to sea on its own.

When Bukang-i was first spotted in the waterway on Sept. 18, officials assumed it had entered in search of food and then become disoriented by the waterway's bent shape, which made it difficult to find the exit.

That assumption was the basis for the decision to attempt a rescue.

With the shark having gone out of its way to return inside the net, however, authorities now find themselves needing to reconsider why Bukang-i entered the waterway in the first place.

For now, authorities have decided to halt further rescue attempts and remove the net, giving the shark a clear path to leave on its own.

The National Institute of Fisheries Science is monitoring Bukang-i's health daily. Based on its swimming behavior and overall condition, the shark appears to be in good health.

Food availability and water temperature are seen as the key factors that will determine whether Bukang-i eventually returns to the sea.

The waterway is known to be home to mullet and other fish species that could serve as prey for the shark.

As temperatures drop and the water in the waterway cools, conditions could become increasingly inhospitable for Bukang-i.


yul@heraldcorp.com