In Pictures: Hundreds of dead fish wash ashore at Hong Kong beach after algae bloom spotted in water

Hundreds of dead fish have washed ashore as an algae bloom was spotted at a Hong Kong beach on Wednesday morning.

Red tides Algae bloom St. Stephan's Beach Dead fishes — Dead fish at St. Stephen’s Beach on March 22, 2023. Photo: Kyle Lam/HKFP.

Red tides were seen in the waters off St. Stephen Beach, in Stanley. The sand was strewn with dead fish and there was a fetid smell, an HKFP reporter observed.

Lifeguard services at the Leisure and Cultural Services Department-managed beach are suspended throughout winter, until April. Similarly, the water quality is not graded by the Environmental Protection Department in the winter months. There were no swimmers at the beach on Wednesday morning, while a man was taking seawater samples with a bucket.

The AFCD told HKFP it has conducted site investigations after receiving a number of red tide reports at beaches in Southern District on March 21 and 22.

It added that no apparent mortality of other marine life has been observed on site apart from some dead fish found along the shore. The red tide is formed by Noctiluca scintillans, which is a non-toxic species commonly found in Hong Kong waters, according to the department.

Red tides, or algae blooms, are caused by an increase in the concentration of microscopic algae in the water. They can be harmful to marine life and humans, with some producing toxins that can cause respiratory problems, skin irritation, and other health issues.

The algae gave the water near St Stephen’s Beach a brownish-red hue. However, no red tide was seen at the nearby beach Stanley Main Beach, where the water quality was graded as “good.”.