The company has been hammered by the coronavirus, with all its parks closed March 13.
But SeaWorld’s woes date to 2013, after a documentary film, "BlackFish," criticized its treatment of captive killer whales. Park attendance suffered afterward.
The Orlando, Fla., company's stock more than tripled from its Nov. 20, 2017, low until Feb. 14, 2020. Since then, the spread of the coronavirus to a pandemic has helped spark a 71% plunge for the stock.
SeaWorld named Marc Swanson, its chief financial officer, to serve as interim CEO. He was also interim CEO before Rivera took the top post in November.
Elizabeth Castro Gulacsy has been named CFO. She'd been chief accounting officer.
Rivera chafed at the board’s involvement in decision-making for operations at SeaWorld, the company said in a regulatory filing. He isn’t entitled to, nor is he seeking, severance payments, the company said.
SeaWorld has had a number of CEOs, at least eight of them in the past six years. The CEO whom Rivera succeeded, Gustavo Antorcha, left after serving seven months.
Shares of other theme-park companies have also hit the skids during the coronavirus scourge as the companies have been forced to close their facilities.
At last check, SeaWorld shares traded at $10.16, up 12%.