Previous Red Tide Occurrences

Click on the week for red tide occurrences during that period in the past month

> 2025/04/25 - 2025/05/02

> 2025/04/17 - 2025/04/25

> 2025/04/11 - 2025/04/17

> 2025/04/03 - 2025/04/11

 
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Overview of the period 2025/04/25 - 2025/05/02

A red tide was sighted over the past week, an inter-departmental red tide working group reported today (May 2).

The red tide was spotted by staff of the Environmental Protection Department on April 25, at Tolo Harbour including Yim Tin Tsai fish culture zone. The red tide has dissipated. No associated death of fish has been reported.

A spokesman for the working group said, "The red tide was formed by Gonyaulax polygramma, which is commonly found in Hong Kong waters and non-toxic. "

The Agriculture, Fisheries and Conservation Department (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.

Please click here to view the location of red tide sighted in Hong Kong waters.

Last update: 2025/05/02 noon

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Overview of the period 2025/04/17 - 2025/04/25

Nine red tides were sighted during the past week, the Inter-departmental Red Tide Working Group reported today (April 25).

On April 18, mariculturist spotted the first red tide at Sham Wan fish culture zone. On April 22, staff of the Agriculture, Fisheries and Conservation Department (AFCD) spotted the second red tide at Tap Mun fish culture zone. On April 22, staff of the Leisure and Cultural Services Department (LCSD) spotted two red tides in Golden Beach and Kadoorie Beach, Tuen Mun respectively. On April 23, LCSD staff spotted three red tides at Ma Wan Tung Wan Beach, Ting Kau Beach, Lido Beach and Casam Beach, Tsuen Wan respectively. At the same day, AFCD staff spotted a red tide in Western waters of Hong Kong. On April 24, members of the public spotted a red tide in Victoria Harbour.

The red tides at Sham Wan fish culture zone, Tap Mun fish culture zone, Western waters of Hong Kong and Victoria Harbour still persist, while the other five red tides have dissipated. No associated fish deaths have been reported as of today.

A spokesman for the working group said, "The red tides at Sham Wan fish culture zone and Tap Mun fish culture zone were formed by Gonyaulax polygramma, which is commonly found in Hong Kong waters and is non-toxic. The other seven red tides were formed by Mesodinium rubrum, which is commonly found in Hong Kong waters and is non-toxic. "

The AFCD urged mariculturists at the fish culture zones of Yim Tin Tsai, Yim Tin Tsai East, Yung Shue Au, Lo Fu Wat, Tap Mun, Kau Lau Wan, Sham Wan, Ma Wan, Lo Tik Wan, Sok Kwu Wan and Cheung Sha Wan 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.

Please click here to view the location of red tide sighted in Hong Kong waters.

Last update: 2025/04/25 noon

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Overview of the period 2025/04/11 - 2025/04/17

 Three red tides were sighted during the past week, the Inter-departmental Red Tide Working Group reported today (April 17).

On April 11, staff of the Marine Department spotted the first red tide at Sai Kung Public Pier. On April 15, staff of the Agriculture, Fisheries and Conservation Department (AFCD) spotted the second red tide in Kau Sai Fish Culture Zone. On April 16, the public spotted the third red tide at Port Shelter.

Apart from the first red tide, which has dissipated, the other two red tides still persist. No associated fish deaths have been reported as of today.

A spokesman for the working group said, "Three red tides were formed by Gonyaulax polygramma, which is commonly found in Hong Kong waters and non-toxic."

The AFCD urged mariculturists at the fish culture zones of Ma Nam Wat, Kau Sai, Kai Lung Wan, Tai Tau Chau, Leung Shuen Wan and Tiu Cham Wan 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.

Please click here to view the location of red tide sighted in Hong Kong waters.

Last update: 2025/04/17 noon

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Overview of the period 2025/04/03 - 2025/04/11

No red tide was reported during this week.

Last update: 2025/04/03 noon

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