Thomas Cook, one of the largest travel companies in the U.K., announced Sunday it will no longer sell tickets to attractions which keep killer whales in captivity — including SeaWorld Orlando.

Peter Fankhauser, the CEO of Thomas Cook, wrote in a blog post that while SeaWorld and other parks keeping orcas passed the required audits and made improvements for their animals, “more than 90 percent” of its customers said they were concerned about animal welfare, leading to its decision not to do business with attractions keeping killer whales in captivity.

“This was not a decision we took lightly,” Fankhauser wrote. “We always said that we would continue to review our policy, conscious that the more we got into this area, the more we would learn, and conscious also of changing customer sentiment.”

The company will continue offering SeaWorld tickets through next summer.

The Association of Zoos and Aquariums (AZA), which is responsible for evaluating and accrediting public animal exhibits, came to SeaWorld’s defense. According to AZA president and CEO Dan Ashe, SeaWorld was given a perfect 100 percent rating in the audit ordered by Thomas Cook.

“SeaWorld Orlando is a responsible member and leader within our community that has consistently achieved accreditation for the last 35 years,” Ashe said in a statement. “Not only do the dedicated professionals at SeaWorld provide their animals with exceptional care, but they also provide significant support for the rescue of injured marine mammals and sea turtles. Guests to SeaWorld Orlando can be assured that their visit is educational, family-friendly, and supports SeaWorld’s efforts to help save animals from extinction.”

In its own statement, SeaWorld reiterated that it no longer breeds orcas but the ones already in its parks will remain there “for many years.”

The public rebuke by Thomas Cook is the latest setback to SeaWorld’s image. Since the release of the 2013 documentary “Blackfish,” which questioned the park’s use of captive orcas, attendance at the Orlando park has dropped from 5.3 million to 3.9 million in 2017.

The first quarter financial report had some positive signs for SeaWorld with attendance up nearly 15 percent across all its parks nationwide compared to the same period in 2017. The Orlando park is hoping for a boost later this summer when it opens Infinity Falls, which SeaWorld has called the world’s tallest river rapids ride.