ORLANDO — Southwest Airlines and SeaWorld Entertainment are ending their 25-year-old marketing partnership, officials with both companies said Thursday, as the airline has been urged by animal rights activists to terminate the relationship. The partnership won't be renewed at the end of the year when the current contract expires. As part of the partnership, three Southwest airplanes were painted with various SeaWorld animals. Those planes will be returned to Southwest's traditional livery. SeaWorld also had Southwest signs in its parks, and Southwest offered vacation packages to SeaWorld, as it does to other tourist destinations. The vacation packages will continue. Officials from SeaWorld Entertainment, which also owns Busch Gardens in Tampa, said the decision was mutual. SeaWorld wants to concentrate on growing markets in Latin America and Asia, the marine park company said in a statement. "Southwest and SeaWorld have enjoyed their long relationship, and wish each other continued success," the statement said. SeaWorld has parks in Orlando, San Antonio, Texas, and San Diego. Southwest spokeswoman Marilee McInnis said it was a business decision as the airline intends to focus on international service. Earlier this year, animal rights activists held a rally and dropped off a petition to Southwest, urging the airline to end the relationship. The activists cited the documentary Blackfish, which explores what might have caused the killer whale Tilikum to kill SeaWorld trainer Dawn Brancheau in 2010. The documentary argues that killer whales, when in captivity, become more aggressive to humans and one another. Since the documentary, several entertainers have pulled out of planned performances at SeaWorld Entertainment parks. Regarding the pressure from activists, McInnis said Southwest has been in "listening and education mode." "We . . . have engaged and heard from conservationists, SeaWorld supporters and others on all sides of this issue," McInnis said.