Several animal activist groups have sent a letter to the Chinese investors in  SeaWorld Entertainment urging them to keep captive animals out of any theme parks it may open.

The Zhonghong Zhuoye Group purchased a 21 percent stake in SeaWorld last month from the Blackstone group. As part of the deal, SeaWorld said it would provide advisory services and support for theme parks, water parks and family entertainment centers in China, Taiwan, Hong Kong and Macau.

The letter said that as films such as “Blackfish” have been released around the world, “people have learned that far-ranging orcas and other marine mammals suffer and die prematurely in SeaWorld’s tiny tanks—and attendance has plummeted.”

Nearly 40 orcas have died on SeaWorld’s watch and it still holds more than 20 in captivity, according to the letter. Attendance by annual pass holders at SeaWorld Orlando dropped 14 percent in 2016 from the previous year. SeaWorld finished 2016 with a net loss of $12.5 million.

“Today’s public is too well-informed to buy tickets to see deprived orcas floating listlessly in concrete tanks,” said Tracy Reiman, PETA’s executive vice president. “We’re asking SeaWorld’s new investors to switch to innovative, exciting, non-animal attractions, not perpetuate the same old marine-mammal prisons.”

The letter was sent by PETA, Sea Shepherd Global, the Animal Legal Defense Fund, the Kimmela Center for Animal Advocacy, the International Marine Mammal Project of the Earth Island Institute, In Defense of Animals and Sonar.

“Denied the freedom of the ocean, these intelligent, family-oriented animals float listlessly or swim in circles in small, barren concrete tank,” according to PETA. “Stress and the absence of intellectual stimulation take a toll on their physical and mental well-being, as well as that of the captive bottlenose dolphins, beluga whales and other animals at the company’s parks.”

PETA—whose motto reads, in part, that “animals are not ours to use for entertainment”—is calling on SeaWorld “not to flee overseas but rather to develop ocean sanctuaries in which orcas could finally have some semblance of a natural life.”

Stephanie Shaw, corporate liaison for PETA, said Wednesday that the Zhonghong Zhuoye Group has not responded to the letter.