Indonesia: Lake Maninjau in dire straits from ‘keramba’ (caged fish) overfarming

Syofiardi Bachyul Jb, The Jakarta Post 6 May 15;

The West Sumatra Environmental Management Agency (BPLHD) has urged the Agam regency administration immediately to remove 10,000 floating fish cages (keramba) from Lake Maninjau to prevent further damage to the environment.

Agency head Asrizal Asnan said the lake was currently home to more than 16,000 floating cages owned by local residents and entrepreneurs, despite a maximum capacity of 6,000 cages.

“The water pollution in Lake Maninjau has reached an alarming level. If the condition is not immediately improved, water pollution could further worsen and the lake could be rendered unusable,” Asrizal told The Jakarta Post on Tuesday.

The problem, said Asrizal, was a result of the widespread presence of keramba on the lake long before a masterplan on lake management was formulated.

In 1992, West Sumatra Fisheries Office conducted a trial program, installing 17 keramba in the clear water of the 9,737.5 hectare lake.

The experiment successful, many locals followed suit with their own keramba, financed by a number of entrepreneurs. By 2009, the number of keramba had reached 8,829 and by this year, that number had doubled to 16,280.

“The boom has led to the death of hundreds of tons of fish annually as a result of poisoning from excess feed and rising sulfur from the floor of the volcanic lake, but entrepreneurs have persevered,” said Asrizal.

Three years ago, the West Sumatra BPLHD designed a masterplan to manage Lake Maninjau, with input from fishery and environmental experts, who determined that the maximum number of keramba that could be accommodated on the lake was 6,000. The masterplan was made official through Regency Bylaw No. 5/2014 on management of Lake Maninjau.

Bung Hatta University fishery expert Hafrijal Syandri said the waters of Lake Maninjau were currently heavily contaminated because of the rampant keramba.

“The lakewater is heavily polluted, with contaminants derived from excess feed, fish faeces and metabolism remnants from the keramba making up 94 percent of the pollution,” Hafrijal told the Post on Tuesday.

“Based on our assessment, keramba fishery activity from 2001 to 2013 produced 111,889 tons of sediment. The depth of the lake has decreased at an average of 16 to 89 m. This has caused the phenomenon of annual mass fish death. From 1997 to March this year, a total of 17,043 tons of fish died, causing losses of up to Rp 200 billion [US$15 million].”

Hafrijal said that the ideal way to save the lake was to issue a moratorium on keramba activity so that the water condition could be restored over the course of 25 years.

“However, that would be impossible because of the impact on people’s livelihoods. One feasible step would be to reduce the number of keramba in stages so that over 10 years, the number could drop to 6,000. This would help restoration, although it would take longer. I hope the Agam Regency administration will act quickly,” said Hafrijal.