Eight red tides have occurred this year off the coast of east China's Fujian province, and the algal blooms have killed millions of abalone, according to local authorities.
A 278-square-km red tide covering a sea area of Pingtan county in Fujian was threatening local abalone farms, according to the Ocean and Fisheries Department of Pingtan County.
The department said that the algal bloom had suffocated 55 million abalone since Saturday, and inflicted direct economic losses of more than 220 million yuan (35 million U.S. dollars).
"I will lose over 2 million yuan," said Zhuo Ronglan, a Pingtan abalone farmer.
Red tide can devastate fishery and aquaculture industries as the algae removes oxygen from the water, suffocating sea creatures.
Red tide might be caused by seawater pollution, changing water temperatures, lingering rains and over fishing, according to the department's website.
Abalone is considered a delicacy for many and Fujian exports thousands of tonnes of it to Japan, the Republic of Korea as well as China's Hong Kong and Taiwan each year.