History of red tide / HAB in Hong Kong

The Agriculture, Fisheries and Conservation Department (AFCD) started to record the occurrences of red tide since 1975. From 1975 to 2009, a total of 817 red tides incidents were recorded in Hong Kong waters. Amongst these incidents, only 27 were associated with fish kills.

A total of 73 algal species have been recorded to form red tides in Hong Kong, but majority of them are harmless. 14 of these algal species are considered as harmful or toxic. Amongst these harmful/toxic algal species, 5 of them resulting in fish kills and the other two causing contamination of shellfish by toxin in Hong Kong. The red tide associated fish kill events were mostly recorded in the 80's and early 90's.

Algal species causing fish kills

Karenia digitata Gymnodinium sp. Karenia mikimotoi     Chattonella marina Chattonella ovata

 

Algal species causing shellfish toxin contamination

Alexandrium catenella Alexandrium tamarense