Indonesia, Lake Toba: Fish cages blamed for dead fish, environmental damage

Apriadi Gunawan and Syofiardi Bachyul The Jakarta Post 7 May 16;

Tourists expecting to enjoy the beauty of Lake Toba over the long weekend may be disappointed as the lake has been contaminated by thousands tons of dead fish in the Haranggaol waters, Simalungun, North Sumatra.

In response, 1,000 people of Haranggaol sub-district joined together to remove the carcasses of goldfish and tilapia ( ikan nila ) from the lake on Friday.

Hasudungan Siallagan, a cage-culture fish farmer, said the locals were willing to clean Lake Toba because they wanted to prevent the dead animals from polluting the water, which could affect tourism and make the water unsafe for use by residents.

“Up to 820 tons of dead fish have been lifted from the fish cages in Lake Toba in the past two days. And today, 1,000 tons of dead fish will be lifted out,” Hasudungan told The Jakarta Post in Haranggaol on Friday, adding that 1000 tons of dead fish had been found as of Wednesday.

He added that about 116 cage-culture farmers in Haranggaol had reported that their fish were dead.

“We have been managing fish cages in Lake Toba for decades and this is for the first time we have seen the mass death of fish,” he said.

“All of the fish from two zones are reportedly dead, from a total of six zones of fish cages in Haranggaol. So, there are only four zones left and I haven’t got any news about that,” he said.

Hasudungan said the farmers had suffered billions of rupiah in losses because of the mass death of fish. He also said local government research into the incident had concluded that the cause of the mass death was lack of oxygen.

Head of the Simalungun district Agriculture and Fisheries Agency, Jarinsen Saragih, confirmed that the cause of the mass death of fish in Lake Toba was an oxygen shortage triggered by the postponed fish harvest.

“Lack of solar radiation since April 28 has also aggravated the oxygen shortage,” he told the Post on Friday.

Jarinsen dismissed speculations that the mass death of the fish was because of water pollution in Lake Toba, adding that “the dead fish were only found in the fish cages, not in the lake”.

Meanwhile, the local government of Agam district in West Sumatra plans to decrease half of floating net cages in Maninjau Lake in order to improve the ecosystem.

Head of Agam Maritime and Fisheries Affairs Agency, Ermanto, said that his team had recorded the number of floating net cages and instructed their owners to gradually reduce the amount in the lake.

“The lake water is heavily polluted. There is a lot of sediment from residual feed and tons of dead fish found every year. If left unchecked, fish will not be able to live inside the cages,” Ermanto told the Post recently.

According to the fisheries agency’s records, there are 16,964 fish cage swaths containing 4,000 minnows in the lake area of 99.5 kilometers. A total of 10,765 swaths are made of iron and 6,199 are made of bamboo.

Ermanto said he would regulate that all fish cages must be made of fiber and not iron, which can rust, or bamboo, which can decay.

Currently, there are 5,520 fish cages owned by 146 locals. Each of them own up to 250 cages. The local government plans to limit cage ownership to a maximum 20 fish cages per owner.