January 4, 2010

Plankton bloom decimates Singapore's fish production

More than 200,000 fish, nearly the entire stocks of 13 fish farms in Singapore, have been wiped out by a plankton bloom in the waters off Pasir Ris Beach.

The problem may worsen as fish in farms further out at sea near Pulau Ubin are beginning to die as well. Fish farmers said this is their biggest loss in the past 10 years.

Six farmers said they have lost hundreds of thousands of dollars from these stocks, cultivated over the last two years; the tiger garoupas had been primed for harvest for next month's Chinese New Year.

Plankton bloom drains the seawater of oxygen, suffocating fish and other marine animals.

When the first signs of trouble begun, the farmers placed air pumps in the net cages to raise oxygen levels in the water, cages were lowered further into the sea and medicine was fed to the fish. Fish were also released into the sea to increase their chances of survival, but nothing worked.

Investigations by the Agri-Food and Veterinary Authority (AVA) show that the current plankton bloom was triggered by a combination of factors. One is the fickle weather, which has shifted between bouts of sunshine and heavy rain. Another is seawater becoming enriched by nutrients from the land, which were washed into the sea by the rain. The third factor lies in the tides; evidence revealed that little water exchange - and thus little flushing - occurs between high and low tides.

The farmers said they do not have enough capital to rebuild their stocks and even if they did, they do not know when it would be safe to start rearing fish again.

The AVA estimates that the 13 affected farms supply 0.5% of the fish consumed in Singapore each year. The marine aquaculture industry, comprising 106 licensed coastal floating netcage fish farms in all, occupies 85.5 hectares of coastal water.

It produced some 3,235 tonnes of fish valued at SG$11.4 million (US$8.1 million) in 2008, accounting for 4-5% of the fish consumed here annually.

The target is to raise this to 15% or 15,000 tonnes annually.