High temperature fatal to species, which thrives in cooler seawater

Manager Sun Guanghao sighed when asked about the summer output of his sea cucumber farm - known as Yushengyuan - in Dalian, Liaoning province.

"Hundreds of hectares of sea cucumbers have died because of the heat that has persisted for a week," he said. "This long of a heat wave has not been seen for decades in this region." He added that the economic losses on his farm alone could surpass 50 million yuan ($7.3 million).

Sun was among a growing number of sea cucumber farmers in the coastal province who have suffered a blow as the heat wave expanded to the once cooler northeastern province over the last few weeks.

The weather, which settled in Liaoning on July 28, has taken its toll on more than half the 122,000 hectares of breeding areas for the marine animals in the province, with economic losses amounting to 6.8 billion yuan, according to the local marine fishery authority.

Dalian, a tourist city known for its cool weather in summer, has been a major production area for sea cucumbers. Almost one-fourth of the national output came from the coastal city in 2016, according to an industry report released in July.

The species thrives in saline water between 10 and 18 C. When the temperature reaches 24 C, it enters a dormant state. Temperatures higher than 28 C can be fatal.

Most of the local farmers raise the species in an enclosed pond, a practice that helps accelerate the animal's growth. But a lack of circulation makes them susceptible to heat in summer.

Sun, the manager of the farm, said the city has seen heat waves before, but they usually last one or two days. The latest has been extra-long, and has been devastating to his farm.

"When the hot weather lasts for more than three days, the species begins to die in large numbers. A week later, you could hardly find any live ones," he said.

The local meteorological center has issued a series of heat warnings. Temperatures in most of the province's inland areas reached above 37 C on Thursday and Friday. In the provincial capital, Shenyang, the temperature reached 38.4 C on Thursday - the highest since the 1950s.

A report by China Central Television said insurance companies in Dalian introduced water temperature insurance in 2014 for local sea cucumber farmers, which compensates for losses caused by hot temperatures. But the insurance didn't prove to be popular, and only two farms bought it this year.

Sun was unwilling to buy the insurance because the premium was high, ranging from 1,500 yuan to 4,500 yuan per hectare.