Harmful algal blooms and associated fisheries damage in East Asia: Current status and trends in China, Japan, Korea and Russia

•Noxious HAB species were Karenia mikimotoi (China), Chattonella antiqua (Japan) and Cochlodinium polykrikoides (Korea).•In China, fish kill cases were mainly caused by Karenia mikimotoi, Heterosigma akashiwo and Chattonella spp.•In Western Japan, fish kill cases were mainly caused by K. mikimotoi, Chattonella spp., Heterosigma sp. and Cochlodinium spp.•In Korea, fish kill cases were mainly recorded by Cochlodinium polykrikoides and Karenia mikimotoi. Occurrences of harmful algal blooms (HABs) and associated fisheries damage have been continuously monitored since the 1970s along the coasts of East Asia. Fisheries damage comprises mass mortalities of fish and shellfish mainly by harmful dinoflagellates and raphidophytes (e.g., Chattonella antiqua/marina, Cochlodinium polykrikoides and Karenia mikimotoi), and contamination of algal toxins in shellfish in particular Diarrhetic Shellfish Toxins by Dinophysis spp. and Paralytic Shellfish Toxins by Alexandrium spp. Shellfish mass mortalities due to Heterocapsa circularisquama in Hong Kong and western Japan, and fish kills by Karlodinium digitatum are unique incidents for this region, whereas C. antiqua/marina, C. polykrikoides and K. mikimotoi are common also in other regions. Time series data showed that the highest bloom numbers were recorded in 1980 (Japan), in 1998 (Korea) and in 2003 (China), followed by decreasing trends in these countries. These data suggest a shift in microalgal species composition, from dominance by diatoms to dinoflagellates after 1980s in Korea, and from diatoms to small haptophytes and cyanobacteria after 2013 in eastern Russia. HAB species composition and the changes were compared among countries, for better understanding on current status and trend of HAB species in East Asia.