ORLANDO, Fla. — Southwest Airlines and SeaWorld Entertainment are ending their 25-year-old marketing partnership, officials with both companies said Thursday, after the airline was 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 had various SeaWorld animals painted on their bodies, including Shamu One. Those planes will be returned to Southwest’s traditional livery. SeaWorld also had Southwest signage in its parks, and Southwest offered vacation packages to SeaWorld, as it does to other tourist destinations. The vacation packages will continue. SeaWorld officials 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, Fla., San Antonio and San Diego. Southwest spokeswoman Marilee McInnis said it was a business decision as the airline intends to focus on international service. In January, more than a dozen animal rights activist held a rally and dropped off a Change.org petition signed by more than 27,000 people at Southwest’s headquarters at Dallas Love Field, urging the airline to end the relationship. The activists cited the documentary, “Blackfish,” which raised questions about the treatment of orcas at SeaWorld and the circumstances that 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 each other. Since the documentary, several entertainers have pulled out of planned performances at SeaWorld Entertainment Inc. parks.People for the Ethical Treatment of Animals has petitioned SeaWorld for years to stop exhibiting animals. Robin Merritt, a former PETA worker who is now a university adviser in Edwardsville, Ill., said that she began the Change.org petition because Southwest’s marketing resonated with so many people. “I felt like Southwest had a been a cheerleader for SeaWorld and if a company like that were to end their ties with SeaWorld it would be a big wake-up call,” she said. “Hopefully people will look more into animal cruelty and stop going to SeaWorld.” She also said of Southwest: “I’d like to think they made the compassionate choice.” Regarding the pressure from the 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. This article includes material from Bloomberg News.