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Red tides sighted
Friday, April 12, 2024

Two red tides were sighted during the past week, the Inter-departmental Red Tide Working Group reported today (April 12).

The first red tide was spotted by a member of the public on April 5 at Yi Pak Wan and Sam Pak Wan, Lantau Island. On April 8, staff of the Leisure and Cultural Services Department spotted another red tide at Silverstrand Beach, Sai Kung. Both red tides have dissipated and no associated fish deaths have been reported as of today.

A spokesman for the working group said, "The red tide at Yi Pak Wan and Sam Pak Wan, Lantau Island, was formed by Noctiluca scintillans and Heterosigma akashiwo, and that at Silverstrand Beach, Sai Kung, was formed by Noctiluca scintillans. Noctiluca scintillans is non-toxic, while Heterosigma akashiwo might produce neurotoxins and kill fish by damaging their gills, according to overseas literature. The two algal species are commonly found in Hong Kong waters."

The Agriculture, Fisheries and Conservation Department (AFCD) urged mariculturists at Ma Wan, Cheung Sha Wan, Ma Nam Wat, Kau Sai, Kai Lung Wan, Tai Tau Chau, Leung Shuen Wan, Tiu Cham Wan and Po Toi O 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.