‘Fishing king-predator’ freshwater cormorant plagues municipalities nationwide

“I’m forced to quit my 43-year-old fishing business because of freshwater cormorants”

Mr. Lee Jae-wan (65), who makes a living from inland surface fishing in Danyang, Chungcheongbuk-do, has a bad feeling whenever he sees freshwater cormorants in the Namhang River. Hundreds of them flock together and eat fish as they come. “Freshwater cormorants have been settling in the Namhang River for many years, and now their numbers have increased significantly,” says Lee. “The cormorants are destroying the Namhang River ecosystem by eating native fish such as sand mudfish and sparrowhawks.”

Freshwater cormorants first appeared in the Namhan River in Danyang in the winter of 2017. At first, there were only three or four birds, but now there are hundreds.

As the number of freshwater cormorants has increased, the catch of inland fishermen has decreased. Each cormorant eats 700 grams of freshwater fish per day. “The five nets I set up every evening were full of fish, and I used to harvest 20 kilograms of fish per net,” Lee said, adding, “Recently, the nets have been empty.”

Local governments across the country are grappling with the issue of freshwater cormorants, which have been displaced from their wintering grounds by the climate crisis. They are called “fishing kings” or “underwater predators” because they eat freshwater fish whenever they can, increasing their population.

“Freshwater cormorants are currently inhabiting all over Chungbuk Province and destroying the ecosystem,” the Chungbuk Provincial Government said on Friday, adding that it recently recommended to the Ministry of Environment to designate them as harmful wildlife. It is estimated that more than 3,000 freshwater cormorants live in Chungbuk.

In recent years, the number of freshwater cormorants has been increasing rapidly in Gyeongpo Lake in Gangneung City, Gangwon Province, a representative lagoon on the east coast. A group of cormorants occupy a rocky island near Wolpajeong in Gyeongpo Lake on April 10. Yonhap News Agency

The damage is also severe. In Cheongju, more than 300 private fishing spots have been damaged by freshwater cormorants. In Chungju, Jecheon, Okcheon, and Danyang, inland fishermen are complaining of reduced catches.

The situation is similar in other provinces such as Gangwon Province. Gangwon Province’s inland fish catch plummeted from 933 tons in 2017 to 613 tons in 2021. According to a survey by the Gangwon Research Institute, more than 20,000메이저사이트 cormorants live in 42 rivers, lakes, and reservoirs in the province.

The feces of freshwater cormorants are causing willow colonies in Chuncheon’s Soyang River to turn white and die. At Yongdam Lake in Jinan-gun, home to more than 1,000 freshwater cormorants, there are reports of reduced fish catches and deteriorating water quality. Yongdam Lake is a drinking water source for people in Jeollabuk-do.

As the freshwater cormorant population surges, the damage is likely to increase. According to the Ministry of Environment’s National Biological Resources Center, the number of freshwater cormorants nearly doubled from 16,021 in 2017 to 32,096 last year. The number of observation sites also increased from 95 in 2017 to 168 last year.

Experts believe that the freshwater cormorant, a winter migratory bird, has become a native species due to environmental and climate changes in Korea. “The freshwater cormorant feeds by diving, but it seems to have become a native bird because rivers and streams have become deeper and richer in fish due to river maintenance,” said Park Hee-cheon, head of the Institute of Bird Ecology and Environment. “In addition, climate change has improved the habitat environment, and the number of cormorants is increasing by taking away the habitat of egrets and herons.”

Local governments are trying to control the population by using noise guns to repel cormorants and installing natural enemies. According to the Wildlife Protection and Management Act, freshwater cormorants cannot be captured. In addition, freshwater cormorants are listed as an endangered species of concern. The Ministry of Environment currently allows only non-lethal methods of population control, such as pruning and thinning.

“The damage caused to fishermen by freshwater cormorants is serious, and it is urgent to take measures,” said an official from Chungbuk Province. “The Ministry of Environment should manage the population through captivity to protect fishermen and the ecosystem.”