Since late June this year, multiple coastal areas in Hainan have experienced two consecutive red tide disasters, leading to extensive death of aquaculture fish. In Changjiang County, several million fish fry have been killed, resulting in an estimated economic loss of nearly ten million yuan.
On June 27, the Hainan Provincial Oceanic and Fisheries Department issued an announcement, declaring a Level III emergency response to the red tide disaster province-wide. The announcement stated that on June 26, red tides were detected in the sea areas near Changjiang County, Danzhou City, Lingao County, and Chengmai County in western Hainan Province. According to preliminary statistics, the largest affected area reached 187 square kilometers, causing economic losses that may have met the Level III standard (between 20 million and 100 million yuan).
On June 30, the emergency response level for the red tide disaster was elevated to Level II by the Hainan Provincial Oceanic and Fisheries Department, and this emergency response was lifted on July 7.
However, just 5 days later on July 12, the department issued another announcement stating that new red tide disasters had occurred in some sea areas of Hainan, leading to the death of fish in Letong and Sanya.
On July 13, a staff member of the Chengmai Yubao Deep Sea Net Cage Aquaculture Professional Cooperative in Chengmai County told Caixin.com that their cooperative had 9 net cages, with 3 of them experiencing the death of 60,000 catties of giant grouper due to the red tide, resulting in an economic loss of over one million yuan.
A person in charge of a marine aquaculture enterprise in Changjiang County mentioned that although red tides occurred in previous years, they had minimal impact on fish farming. However, this year’s red tide area is several times larger than in previous years, causing the company to lose approximately 3.2 million golden pomfret fry, valued at nearly ten million yuan.
An individual responsible for Hainan Blue Grain Technology Co., Ltd. in Sanya also estimated losses of over tens of millions of yuan for the company, which had raised millions of fish fry in Sanya for more than a decade, never encountering a red tide of such magnitude.
It was reported that the red tide algae species commonly found in Hainan before were bioluminescent algae and spherical brown cyst algae. However, according to Lu Songhui, director of the Red Tide and Marine Biology Research Center at Jinan University, the red tide algae identified this time is a near-species of Karlodinium veneficum, a first-time discovery in Hainan. The new round of red tide starting on July 12 is also caused by this algae.
Lu Songhui explained, “Red tides are divided into toxic red tides and harmful red tides. The outbreak in Hainan this time is a harmful red tide.” The toxins produced by dominant algae during this red tide can have toxic effects on fish gills, causing respiratory difficulties and death, with a close relationship between algal density and mass fish mortality. However, the impact of these toxins on human health is relatively limited.
Statistics show that as of 2010, Hainan Island had recorded 32 red tide disasters near shore, with 16 occurrences between 2010 and 2017. In 2024 alone, there were three recorded red tide disasters, indicating an increasing frequency of red tide events.