(CNN) -- Willie Nelson is the latest act to cancel a concert at Orlando's SeaWorld in the wake of CNN's "Blackfish" documentary.
The legendary country singer's decision comes after the Canadian rock band Barenaked Ladies pulled the plug on their show at the Florida theme park.
"As a fan who respects his activism for animals, the environment, and other good causes, I find this very disappointing," Danielle Legg of Amherst, New York, wrote in her petition. "If you've seen the documentary Blackfish, you know why it's so surprising. Please tell Willie Nelson you do not want him to support SeaWorld's animal cruelty."
The petition gathered 9,000 signatures.
SeaWorld spokesman Nick Gollattscheck confirmed Nelson's decision not to sing at SeaWorld, but he cited reasons other than the documentary and petition.
"Due to scheduling conflicts, Willie Nelson will not be appearing at SeaWorld Orlando's Bands, Brew & BBQ event in 2014," Gollattscheck said in a statement e-mailed to CNN Thursday night.
Nelson and his representatives did not immediately respond to a CNN request for comment.
When the Barenaked Ladies nixed their plans to play at SeaWorld last week, they explained that it was a decision made after viewing "Blackfish."
"This is a complicated issue, and we don't claim to understand all of it, but we don't feel comfortable proceeding with the gig at this time," the band said on a Facebook post.
"The Seaworld folks have been gracious, and extended us invitations to the park to learn more about what they do, and how they do it."
A park spokesman told CNN that the Barenaked Ladies show had been taken off the theme park's concert schedule.
The decision to cancel the band's performance came two days after drummer Tyler Stewart posted a tweet saying the group is "looking at options" after viewing the documentary.
The documentary -- which first aired on CNN in October -- tells the story of the SeaWorld trainer who was killed in 2010 by an orca named Tilikum.
Fans launched an online petition asking the Barenaked Ladies to cancel. The group had just announced it would perform at SeaWorld's Orlando park on February 15 during its "Bands, Brew & BBQ" events.
Mike Garrett of St. Catharines, Ontario, posted the petition on Change.org asking band members to watch "Blackfish" and "learn how SeaWorld and other captive display facilities such as Marineland in Niagara Falls have for decades exploited marine mammals solely for profit."
Garrett said he was "disappointed" when he heard the group was scheduled to play there "in light of all the horrific information we're learning."
"I'm hoping to grab the band's attention on this issue and ask them, on behalf of all their animal-loving fans, to reconsider performing there," Garrett wrote. His petition gained more than 9,200 signatures.
"We here at Barenaked Ladies have made a decision based on what we feel. It's not about money, or petitions, or press... But it is about our fans," the band said November 27. "We listen to them, and they're important to us."
The park's website does not list Barenaked Ladies on the schedule. February 15 and four other weekend dates just say "Coming Soon."
Acts that are still listed on the calendar include Cheap Trick, REO Speedwagon, Martina McBride, 38 Special, Justin Moore and Scotty McCreery.
CNN's Jane Caffrey contributed to this report.