The first red tide was sighted by staff of the Leisure and Cultural Services Department at Silverstrand Beach in Sai Kung on May 5. The red flag was hoisted at the beach immediately.
On the next day, staff of the Marine Department spotted another red tide at Sha Tin Hoi near Wu Kai Sha.
On May 8, two more red tides were observed by the Marine Police and staff of the Environmental Protection Department at Tung Ping Chau, Cheung Chau Tung Wan Beach and Kwun Yam Beach respectively.
Except for the one at Silverstrand Beach, the red tides have already dissipated. No associated death of fish has been reported in these occurrences so far.
"The red tides at Silverstrand Beach, Tung Ping Chau, Tung Wan Beach and Kwun Yam Beach were formed by Noctiluca scintillans. The one at Sha Tin Hoi near Wu Kai Sha was formed by Gonyaulax polygramma. All these algal species are commonly found in Hong Kong waters and are non-toxic," a spokesman for the working group said.
The Agriculture, Fisheries and Conservation Department (AFCD) urged mariculturists at Cheung Sha Wan, Ma Wan, Yim Tin Tsai, Yim Tin Tsai (East), Yung Shue Au, Lo Fu Wat, Sha Tau Kok, Ap Chau, Kat O, O Pui Tong, Sai Lau Kong, Tap Mun, Kau Lau Wan, Wong Wan, Sham Wan, Kau Sai, Ma Nam Wat, Kai Lung Wan, Tai Tau Chau, Leung Shuen Wan, Po Toi O and Tiu Cham Wan fish culture zones to monitor the situation closely.
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.
