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Red tides sighted
Friday, March 5, 2021

Three red tides have been sighted over the past week, an inter-departmental red tide working group reported today (March 5).
A mariculturist spotted the first red tide on February 26 at Cheung Sha Wan Fish Culture Zone. On February 28, Marine Police officers spotted the second red tide in Sha Tin Hoi. On March 1, staff of the Agriculture, Fisheries and Conservation Department (AFCD) spotted the third red tide at Inner Port Shelter, including Tai Tau Chau Fish Culture Zone.
Apart from the third red tide, which still persists, the other two red tides have dissipated. No fish deaths associated with the three red tides have been reported as of today.
A spokesman for the working group said, "The first and second red tide were formed by Noctiluca scintillans, while the third red tide was formed by Gonyaulax polygramma. Both algae are commonly found in Hong Kong waters and are non-toxic."
The AFCD urged mariculturists at Cheung Sha Wan, Yim Tin Tsai, Yim Tin Tsai (East), Yung Shue Au, Lo Fu Wat, Ma Nam Wat, Kau Sai, Kai Lung Wan, Tai Tau Chau and Leung Shuen Wan 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 to monitor red tide occurrences to minimise the impact on the mariculture industry and the public.