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Press Releases

Red tides sighted
Friday, May 12, 2023

Two red tides have been sighted over the past week, the Inter-departmental Red Tide Working Group reported today (May 12).

Staff of the Agriculture, Fisheries and Conservation Department (AFCD) spotted a red tide at Tolo Harbour (including Yim Tin Tsai and Yim Tin Tsai (East) Fish Culture Zones) on May 11 and spotted another red tide at Tolo Channel and Three Fathoms Cove (including Lo Fu Wat and Yung Shue Au Fish Culture Zones) today. Both red tides persist and no associated fish deaths have been reported as of today.

A spokesman for the working group said, "The red tide at Tolo Harbour was formed by Vicicitus globosus and Heterosigma akashiwo, while the red tide at Tolo Channel and Three Fathoms Cove was formed by Vicicitus globosus. According to literature overseas, Vicicitus globosus may cause respiratory damage in fish, and Heterosigma akashiwo might produce neurotoxins and kill fish by damaging their gills. Vicicitus globosus is not commonly found in Hong Kong waters while Heterosigma akashiwo is commonly found in Hong Kong waters."

The AFCD urged mariculturists at 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 to monitor red tide occurrences to minimise the impact on the mariculture industry and the public.