From www.wdwinfo.com

Cheap Trick and Trisha Yearwood cancel SeaWorld performances
Dec 12, 2013

Cheap Trick has become the fourth band in just over a week to cancel an upcoming SeaWorld performance. The group was scheduled to perform at this spring's Bands, Brew & BBQ event, but cancelled their performance this morning. The band's fans signed a petition on Change.org asking for the cancellation, though the band hasn't officially announced why they were withdrawing. The other three groups - Barenaked Ladies, Willie Nelson and Heart - also cancelled because of fan petitions and their own displeasure with the recent controversial documentary, Blackfish. Blackfish is a collection of interviews with former SeaWorld staff and other experts giving their opinions of the way the marine park treats its killer whales.

Update: According to TMZ.com, Trisha Yearwood has also cancelled her appearance. The source says she hasn't seen the film, but she's "heard all the fuss and that's enough for her."