Chemical poisoning is believed to have killed thousands of fish in the Meriam River in Pidie regency and the Teunom River in Aceh Jaya, Aceh, over the last two weeks.
Dead fish have been found floating in the rivers since July 26. The fish, which include kerling or jurlung (Mahseer fish), are popular among locals as they form part of their daily diet.
Aceh Maritime Affairs and Fisheries Agency head Raihana said her agency was still studying samples of the dead fish, but preliminary findings had shown that the fish were poisoned by chemicals that were polluting both rivers.
“We are still conducting laboratory examinations and analysis but the fish certainly died of some form of chemical poisoning,” she said.
She said results of pathology tests on the fish conducted by the Syiah Kuala University’s School of Veterinary Medicine also indicated poisoning.
However, she could not yet determine which chemicals or the source of the pollution of the two rivers, which are linked.
“We have called on people not to consume fish from the two rivers, dead or alive,” Raihana said, adding that residents were also asked not to bathe or wash in, or drink water from the rivers.
Physical examination on the fish showed that the vital organs of the fish were swollen. They also suffered internal bleeding.
“It’s possible they were polluted by heavy metal elements but we are not yet sure what heavy metal it is,” Raihana said, adding that she expected to get the investigation results within a week.
Separately, activists from the Indonesian Forum for the Environment (Walhi) claimed the pollution might be linked to traditional mining activities conducted by people in the region.
One of the mining sites is located in Geumpang Pidie on the upper reaches of the Meriam River.
“We have warned the administration that if the mining activities continue in a number of areas in Aceh, pollution of rivers would continue to occur,” Walhi Aceh director Muhammad Nur said.
Walhi Aceh noted that pollution of river areas had been occurring since 2009 and some 250,000 hectares of protected areas had been turned into both legal and illegal mining sites.
Muhammad urged the provincial administration to take serious action to counter river pollution in Aceh, especially pollution related to mining activities.
Meanwhile, Aceh Governor Zaini Abdulah called on residents to cease illegal gold-mining activities, especially the use of mercury.
“Mercury usage without control by the authorities could pollute water and endanger both people and the environment,” Zaini said.
The use of mercury in gold mining is illegal in Indonesia because it is toxic to both human health and the environment. But for people who are lured by the lucrative market for gold, mercury is the easiest way to extract it.
Despite the hazards, obtaining mercury for gold mining activities is relatively easy.
In February this year, the Worldwide Fund for Nature (WWF) Indonesia Aceh also asked the administration to immediately address mercury contamination in the province’s rivers.
The NGO asked officials to learn from the Minamata incident in Japan where mercury contamination caused serious problems, with as many as 65,000 people having suffered ill health as of 2012.