Several red tides have been sighted in Hong Kong waters over the past week, an inter-departmental red tide working group reported today (April 28).
On April 22, two red tides were sighted at Deep Water Bay and Tai Tam Bay, Hong Kong Island.
On April 23, red tide was observed at Clear Water Bay Second Beach, Sai Kung.
On April 25, three red tides were observed at Lei Yue Mun to Tathong Channel (including Tung Lung Chau fish culture zone), Port Shelter and Rocky Harbour (including Kau Sai, Tiu Cham Wan and Tai Tau Chau fish culture zones) and Starling Inlet to Crooked Harbour (including Sha Tau Kok, Ap Chau and Kat O fish culture zones).
Another two red tides were sighted at Hap Mun Bay Beach, Sai Kung, and Tolo Harbour (including Yung Shue Au fish culture zone) on April 26 and yesterday (April 27) respectively.
The red tides at Lei Yue Mun to Tathong Channel, Port Shelter and Rocky Harbour, Hap Mun Bay Beach and Tolo Harbour still persist while the other four red tides have dissipated. No associated death of fish has been reported.
A spokesman for the working group said, "The red tide at Hap Mun Bay Beach was formed by Cochlodinium convolutum and Noctiluca scintillans. The red tides at the other locations were all formed by Gonyaulax polygramma. Noctiluca scintillans and Gonyaulax polygramma are commonly found in Hong Kong waters, and Cochlodinium convolutum is less common. All species are non-toxic."
The Agriculture, Fisheries and Conservation Department (AFCD) urged mariculturists at Ma Nam Wat, Kau Sai, Kai Lung Wan, Tai Tau Chau, Leung Shuen Wan, Tiu Cham Wan, Tung Lung Chau, Po Toi O, Lo Tik Wan, Sok Kwu Wan, Po Toi, Wong Wan, Ap Chau, Kat O, O Pui Tong, Sai Lau Kong, Sha Tau Kok, Yim Tin Tsai, Yim Tin Tsai East, Yung Shue Au and Lo Fu Wat fish culture zones to monitor the situation closely and increase aeration where necessary.
Red tide is a natural phenomenon. The AFCD's proactive phytoplankton monitoring programme will continue monitoring red tide occurrences to minimise the impact on the mariculture industry and the public.