BALIK PULAU: The red tide that killed tens of thousands of farmed fish in Penang and Perak is now heading to Kedah.
Technically called harmful algal blooms (HAB), the phenomenon was first detected in the sea off northern Perak.
The Fisheries Department said during an investigation on May 29, the Fisheries Research Institute found high concentrations of Cochlodinium algal, one of the red tide species, in waters near Kuala Kurau, Kuala Gula and Tanjung Piandang in Perak after a large number of fish, farmed in floating cages at sea, were found dead.
“The fish were killed by HAB. Following the cases in Perak and Penang, we forecast similar incidents will occur in Kedah and urge farmers there to be cautious.
“Farmers should relocate their fish from affected areas and be prepared to harvest if the fish do not look normal.
“Do not simply dispose of dead fish in the sea as it can contribute to an increase in nutrients which causes growth of plankton, ” it said in a statement.
The department said while the spike in Cochlodinium is an annual occurrence worldwide and toxic to marine life, it does not affect humans.
“Fish in the wild are not affected as they can swim away, ” it said, adding that fishermen continued to report good catches at sea.
Universiti Sains Malaysia’s Centre for Marine and Coastal Studies director Prof Datuk Dr Aileen Tan said researchers had detected a spike in the level of chlorophyll in waters around Penang.
“The first peak was on May 21 during spring tide, followed by the second peak on May 28 during neap tide.
“High levels of chlorophyll-A indicates high concentrations of phytoplankton. Growth of bad phytoplankton that form HAB is possibly triggered by the recent rain, which flushed nutrients from land to sea, ” she said.
Prof Tan said a cyclical pattern was showing because large numbers of fish deaths had occurred between April and August last year.
“Fish in cages died by the thousands in Penang and Perak last May.
“If fish deaths occur or repeat at similar times in different years, coinciding with prolonged hot weather followed by rainy seasons, then it can be linked to a combination of natural factors.
“We do have harmful algae in our waters but they can bloom HAB with a high input of nutrients.
“We cannot do much about the rain or the existing harmful algae but we can better manage waste that flows into the sea, which feeds them, ” she added.
On Wednesday, thousands of large snappers and trevallies were washed ashore in Balik Pulau and left a foul stench as their carcasses rotted.
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