BFAR says fish kill in Lake Mainit due to low dissolved oxygen

KITCHARAO, Agusan del Norte (MindaNews / 19 December) – The incidents of fish kill in Lake Mainit have been traced to low dissolved oxygen in the country’s fourth largest lake, initial findings of the Bureau of Fisheries and Aquatic Resources-(BFAR) Caraga said.

Tilapia and carp have been found floating dead in Lake Mainit since a month ago.

The fish kill has affected the livelihood of hundreds of fisherfolk who depend on the lake for their livelihood.

But where are the fisherfolk? Fisherfolk in Barangay San Roque in Kitcharao, Agusan del Norte, hope the incidents of fish kill stop so they can use their boats to go fishing again. MindaNews photo by Roel N. Catoto
But where are the fisherfolk? Fisherfolk in Barangay San Roque in Kitcharao, Agusan del Norte, hope the incidents of fish kill stop so they can use their boats to go fishing again. MindaNews photo by Roel N. Catoto

Fisherfolk in towns of Mainit and Alegria in Surigao del Norte including Kitcharao and Jabongga in Agusan del Norte had earlier said they suspect mining activities upstream are to blame for the fish kill.

Dr. Anne Melisa Talavera, officer-in-charge of BFAR’s Regional Fish Health Laboratory of BFAR, told MindaNews Friday that parts of the lake have low dissolved oxygen, at two parts per million (ppm), from the normal level of at least four ppm.

She said bigger tilapia need more dissolved oxygen to survive.

“That’s exactly one of the reasons why bigger ones are affected by the fish kill in Lake Mainit,” she said.

Using Hach Water Test Kit, Talaver said they conducted an inspection on November 26, December 3, and 9 in the towns of Alegria and Mainit in Surigao del Norte and in Kitcharao, Agusan del Norte on December 16.

BFAR also took samples of water and samples of dead fish for laboratory examinations in Manila.

Nerio Casil, Director of BFAR-Caraga told MindaNews last Thursday that they also tested the water for presence of heavy metals.

“Water and fish are also checked for bacterial analysis,” he said.

Casil debunked reports that their office has done nothing on the fish kill.

“Right after we received information, we immediately acted on it,” he said.

Casil reacted to a statement of Judith Rojas, assistant director of BFAR-Caraga. Rojas last week that their office did not receive any request letter from affected local government units.

“We made an effort immediately. In fact, we are waiting for the results this week from Manila,” Casil said.

Dissolved oxygen levels

Darwin Brain Lawas, a marine biologist of Green Mindanao Association said fish growth usually requires 5 to 6 ppm of dissolved oxygen.

“Dissolved oxygen levels below 3 ppm are stressful to most aquatic organisms. Levels below 2 ppm will not support fish at all,” he said.

There are lots of causes why dissolved oxygen gets low in a body of water. He cited sudden change of water temperature, purity level, algal bloom, soil erosion and siltation.

Talavera said they should have gotten water samples a few days into the fish kill.

“The report came to us late because it was two weeks after the fish kill,” she said.

Talavera stressed that water parameters such as total suspended solids and total dissolved solids were not included in their tests. adding other agencies could do it.

The BFAR-Caraga could not give the exact number of affected fisherfolk in the lake towns despite having launched a program a year ago, to register the number of fisherfolk per municipality.

‘Don’t eat the fish’

Talavera advised residents not to eat the floating dead fish.

“It’s not advisable to eat the dead ones especially those in a state of decomposition,” she said.

She urged fishermen to retrieve the dead fish and bury them to avoid the spread of bacteria.

Talavera said she has not received reports of people who got sick from eating freshly-caught tilapia from the lake.

But majority of the people around lake Mainit have tried not to eat the fish, waiting for official announcement from the BFAR.

As of Saturday, BFAR has not released the results of the laboratory analysis.

Economically affected

Fisherfolk around Lake Mainit are spending a bleak Christmas due to the fish kill.

Junmar Mosende, 33, a fish vendor at the public market said that since the fish kill a month ago, it’s been a month of low incomes for them.

Mosende sells tilapia at for 60 per kilo, from P120 to P140 per kilo before the fish kill.

“Malabo ang pamasko namo ini kay alkansi sa tinda,” (We have a sad Christmas bccause of our losses), he said.

Some eateries here have been abstaining from cooking tilapia.

Nora Ga, a worker of Hill Top Food House, said they have not cooked tilapia since the fish kill occurred.

Fishermen in Barangay San Roque here said this fish kill have adversely affected their livelihood.

Rallies vs mining

“The fish kill has taken its toll on us. Our catch has dwindled. No fishermen could get 10 kilos a day,” said Danilo Alcantara, a village councilor and fisherman.

Alcantara said he would join rallies calling for a stop to mining activities upstream.

“There is an obvious pollution along Magpayang River and the runoff settles into the lake,” he said.

Last week, fisherman Nicolas Goliat, recalled that on normal days, they could earn at least 350 pesos every day for five kilos of tilapia which they sell at 70 per kilo.

Goliat said most of the fisherfolk believe the fish kill was due to the mining operations since a similar incident happened during the operations of Surigao Resources Consolidated (Suricon) in the 1970s to early 1990s.

But Goliat said the current fish kill is not as bad as in the past when Suricon was operating.

“Sauna hurot gyod ang tanan isda sa danao. Lapornas gayod pati pa ang ulang” (In the past, all the fishes in the lake were killed, including the freshwater shrimps).

As of Thursday, Alcantara said they could still see dead fish floating.

Eljoy Azarcon, a fisherman in San Roque said there are more than a hundred fishermen in their village.

“We have more than a hundred boats as you can see along the lakeshore, we rely on the lake for livelihood. Without it, we cannot survive,” he said. (Roel N. Catoto / MindaNews)