Jakarta. Maritime Affairs and Fisheries Ministry’s research body on Tuesday (13/06) warned Indonesian fish farmers to prevent fish dying in their keramba, or fish cages, after a local news outlet reported a mass death of fish in Lampung Bay caused by plankton blooms.
"Mass death of fish in keramba is generally caused by a degradation in local water quality, either from toxic waste or a growing number of phytoplanktons," Toni Ruchimat, the ministry’s head of research, said in a press release received by the Jakarta Globe.
The increase in the number of planktons is usually preceded by an increase of nutrients in the water — usually blue green algae — due to excessive water fertility. The increase in nutrients causes blooming blue green algae to release cyanatoxin, which causes sudden deaths from respiratory failure among fishes.
On Friday, Kompas newspaper reported fishes dying in floating net cages at Lampung Bay in Pesawaran, Lampung. A plankton population boom in December 2012 also led to the deaths of around 400,000 fish, causing more than $1.5 million in losses for fish farmers.
"There are several steps we can take to reduce losses caused by this phenomenon. First, farming must be halted until water conditions improve. Second, fishes close to consumption size must be immediately harvested. Third, we should aerate keramba to increase oxygen in the waters," Toni said.
As plankton sucks oxygen in the water, a boom in its population suffocates other life, including fish, in the water.
Toni cited a study by researchers at the Indonesian Center for Marine and Fisheries Socio-Economic Research (BBRSEKP) in 2011, which recommended waste suction or dredging to reduce pollutants and ensuring the number of kerambas meet a fish farm's carrying capacity.
"It’s very important to research the carrying capacity of the environment in areas intended for a fish farm, especially flooded bay areas where water is limited, or closed waters," Toni said.