Mystery of mass fish death solved


Heavy losses: Workers checking the 50,000 dead cage-bred fish in Teluk Bahang after Typhoon Lekima hit in August.

GEORGE TOWN: The presence of phytoplankton and the high stocking density in fish cages have been blamed for the mass death at fish farms in Teluk Bahang in May.

Task force member and Centre for Coastal and Marine Studies (Cemacs) director Prof Datuk Dr Aileen Tan said the conclusion of the probe was in line with the findings of the Fisheries Department.

“We have ruled out the presence of heavy metal as the cause as it was within permissible levels.

“Our findings show there is a high presence of phytoplankton in the fish cage, which had reduced the dissolved oxygen.

“The high density of the fish in the cages was also a contributing factor as the plankton and fish competed for the available oxygen,” she told The Star yesterday.

Dr Tan said the presence of algal bloom in the waters also played a part as it reduced oxygen in the water.

The fish farmers had claimed that they suffered loss of income after thousands of grouper were found dead.

However, in the case of the fish deaths which took place in August, she said it was due to the tail-end of Typhoon Lekima.

The storm hit the coastal areas and stirred up sediment containing ammonia and nitrates from the seabed, which resulted in a reduction of oxygen in the water.

This low-oxygen condition killed thousands of cage-bred fish as well as their wild counterparts up to a 4km-stretch from the shore.

The state-led task force is expected to present the findings to state Environment Committee chairman Phee Boon Poh and Agriculture and Agro-based Committee chairman Dr Afif Bahardin next week.

The task force comprising Cemacs, the Fisheries Department, the Environment Department and other related agencies probed the presence of heavy metals following the mass fish death in Teluk Bahang, where more than 50,000 cage-bred fish died along with thousands of wild fish after Typhoon Lekima hit in August.

phytoplankton , fish , Teluk Bahang

   

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