(CNN) The Japanese organizer of the World Cup sailing competition has apologized for its decision to open the event near Tokyo with a show of captive dolphins performing tricks.
The Japan Sailing Federation issued the apology Tuesday after participants criticized the performance, including British Olympic silver medalist Luke Patience.
"Couldn't be more embarrassed with what I'm witnessing," Patience tweeted following the event. "We are sailors, and apparently a 'green' sport."
He later apologized on social media for "any offense" that he may have caused, explaining that he was "shocked" that sailors would be taken to the dolphin aquarium for the ceremony.
"As a sport, I hope we can show more morality than this," Patience added.
World Sailing, the sport's overseeing body, also expressed its regret in an email to organizers of the event, according to Japanese national broadcaster NHK.
It said that it had not approved the event, and hadn't received a request for permission from their Japanese organizing counterparts.
The World Cup event, which is being held at the competition venue for the 2020 Tokyo Olympics, is being considered a dress rehearsal for the global sport bonanza.
The country has long been at odds with animal rights activists, who see the country's treatment of marine mammals as cruel.
Graphic images of slaughtered dolphins in red pools of blood attracted worldwide attention when the controversial Taiji dolphin hunt was featured in the Academy Award-winning 2009 film "The Cove."
The annual hunt, in which nearly 2,000 and dolphins and porpoises from seven different species are caught -- and many killed -- in a bloody practice known as "drive hunting," has drawn international condemnation. Japan defends the practice as being in accordance with local customs.
Lincoln O'Barry, the son of former dolphin-trainer-turned-activist Ric O'Barry who starred in the film, criticized the practice following his father's detention in Tokyo in 2016.
"Dolphin hunting in Taiji began in the 1950s and is hardly cultural or traditional. The dolphins that aren't slaughtered are sold to dolphin 'abusement' parks around the world."
Most are killed for their meat, but a "small proportion" are caught for live sales to aquariums worldwide, according to the World Association of Zoos and Aquariums (WAZA).
In 2015, Japanese aquariums narrowly avoided being thrown out of the global industry body by agreeing to stop buying dolphins caught in the controversial Taiji hunt.