SeaWorld is fighting back against critics of the theme park's treatment of animals following a sharp decline in attendance. PR Newswire/AP hide caption

itoggle caption PR Newswire/AP

Elephant acts at Ringling Bros. and Barnum & Bailey Circus will be phased out by 2018, the circus' parent company said today. The elephants will retire to a conservation center in Polk City, Fla. Tamika Moore/AL.com/Landov hide caption

itoggle caption Tamika Moore/AL.com/Landov

Visitors watch an orca performance at SeaWorld in San Diego this year. The company has seen attendance slip in the year since the release of a documentary film critical of the company's captive whale program. Mike Blake/Reuters/Landov hide caption

itoggle caption Mike Blake/Reuters/Landov

Killer whales perform in Shamu Stadium at the SeaWorld Orlando theme park in Florida. SeaWorld says it will not appeal a citation that prohibits trainers from performing with the whales. Phelan M. Ebenhack/AP hide caption

itoggle caption Phelan M. Ebenhack/AP

In a photo released by SeaWorld San Diego, Kasatka, a killer whale who is approximately 37 years old, swims with her newborn calf in February 2013. Mike Aguilera/SeaWorld San Diego/Getty Images hide caption

itoggle caption Mike Aguilera/SeaWorld San Diego/Getty Images

An image provided by SeaWorld San Diego shows Kasatka in December 2004 with a calf she had given birth to just days before. Mike Aguilera/SeaWorld San Diego/Getty Images hide caption

itoggle caption Mike Aguilera/SeaWorld San Diego/Getty Images