Heart is among the list of artists to cancel performances at Sea World after the release of Blackfish – a documentary chronicling the alleged mistreatment of orca whales at the U.S. theme park.

“Seeing Blackfish just really opened our eyes to a lot of really horrific truths…” Ann Wilson told Rolling Stone. “It really broke my heart and I just couldn’t see signing my name to that. We hate to disappoint people who go to hear our music, but this was a larger issue.”.

The film has been a public relations nightmare for the park, who have called it “inaccurate and misleading.” But despite their claims, artists who have backed out of performing at the venue include Joan Jett, Cheap Trick, Willie Nelson, REO Speedwagon, and 38 Special, among others.

“What they do is slavery,” Ann Wilson continued. “Plain and simple.

You can view the trailer for Blackfish below.