Since this century, especially since the 1950s, Japan, the United States, Venezuela, Australia, the Philippines, Guatemala, Malaysia and other countries in the harbor waters, there have been time and again a wide range of red tides, extremely serious damage to fisheries production, endangering human health.

Japan's Seto Inland Sea was originally a scenic fishing grounds, fisheries production accounted for one-half of Japan, farming accounted for one-quarter of Japan. 60's to 70's, the red tide occurred frequently. The fishery and aquaculture industries were almost paralyzed. 48 red tides occurred in Japanese waters in 1967, 133 in 1971, and 326 in 1975. Some red tides continued for years, causing massive deaths of sea life.

In our country sea, red tide endangered human health and life news from time to time. 1986 January, Taiwan Province of coastal residents ate purple clams, resulting in 30 people were poisoned, of which 2 people died. Creating this tragedy is the red tide organisms Tamara Alexandrium macroalgae.In November 1986, Dongshan County, Fujian Province, Xing Chen Township villagers ate the red tide occurred in the area of the Philippine clams, resulting in 136 people were poisoned, of which 1 died, the culprit is the red tide organisms naked Aphanizomenon.In November 1989, Fuding County, Fujian Province, the store countryside under the residents of the red tide area for the red banded weaving snails collected, resulting in 4 people were poisoned, of which 1 person died. one of them died. In Zhejiang Province, from 1967 to 1979, there were more than 40 cases of poisoning caused by the consumption of snails collected after the occurrence of red tide, with 423 poisoned people and 23 deaths.

In June 1957, in the Arabian Sea, a former Soviet cargo ship was sailing forward. Suddenly, the bow of the ship seemed to hit something. The captain of the ship immediately ran to the front to see what was going on, and to his surprise, the originally turquoise-blue sea water turned reddish-brown, interspersed with silver glittering objects. I do not know when, the cargo ship has sailed into the dense schools of dead fish. What's going on here? It turned out that the sea water here had formed a terrible red tide.

November 16, 1986, would have been the early winter season, in this season in the north of China is generally no big precipitation, but in Shandong Province, Dongshan Island area but a heavy rain. Soon after the rain, a red tide occurred in the waters of the Dongshan Island area, and the water quickly turned red. The local fishermen, who had never seen red seawater and did not know the cause of the red tide, were surprised and ignored the red tide, and continued to operate according to their usual habits, opening their nets to catch fish and shrimp and clams, and transporting these seafood products to the market for sale. These so-called "fresh clams" caught from the red seawater were eaten by people, resulting in hundreds of people poisoned, and there are a number of people due to taste too much, poisoning deeper and death.

The red tide in the waters of Dongshan Island in Shandong Province is not an isolated incident, but has occurred many times in many parts of the world. Although the appearance of red tide is not regular, but the occurrence of red tide in the sea is more and more trend, the interval between the occurrence of red tide is also shorter and shorter, the scale and scope of red tide is also more and more large, thus causing harm is also obvious. For example, on March 17, 1972 in Japan's Seto Inland Sea red tide, caused by the sea in the area of 1 / 3 of the death of marine organisms. 1987 Guatemala coast of the red tide led to more than 200 people due to accidental ingestion of marine fish and shrimp poisoning, of which there were 26 deaths. 1987 in the United States of America's East Coast also appeared in the red tide, the waters of the dolphins about 1,500 ~ 2,500 / due to poisoning death. The red tide that occurred in Hong Kong's offshore waters in the spring of 1998 caused direct economic losses to fishermen of nearly 1 billion Hong Kong dollars.

The world's coastal or offshore waters due to eutrophication are varying degrees in the occurrence of "bleeding" phenomenon, and unabated, the loss of increasingly serious. 1994 March, in South Africa's west coast on a wave of more than 50 years on the rare red tide, fish and shrimp piled up all over the beaches, some of the beach, rotten fish and shrimp piled up a full 3 feet thick. 3 feet thick. According to incomplete statistics, China's coast since 1980, *** occurred more than 300 times the red tide, which occurred in 1989, a red tide lasted 72 days, resulting in economic losses of 400 million yuan, only Huanghua, Hebei, 100,000 acres of shrimp on the production of tens of thousands of tons of tons. 1997 October to April 1998 occurred in the Pearl River Estuary and Hong Kong sea surface range of thousands of square kilometers of large red tides to the sea fish industry, the losses caused by the production is also hundreds of thousands of tons. Production losses caused by hundreds of millions of dollars. Then this fall in the Bohai Sea waters occurred once again the largest area (more than 3,000 square kilometers) of the red tide.