(Reuters) - Washington state senators held a hearing on Thursday to consider banning the increasingly controversial capture or holding of killer whales for entertainment. More than half of the approximately 455 orcas taken for captivity originated in Washington state but the practice has come under more scrutiny following the 2013 documentary, "Blackfish," which described the capture of orcas and how one killed a trainer at SeaWorld in Orlando, Florida. Today, 57 orcas are in captivity in 14 marine parks in eight countries, including 25 in SeaWorld parks in Florida, California and Texas, according to a sponsor of the legislation, State Senator Kevin Ranker, D-Orcas Island. Ranker told fellow senators on Thursday that even though there are no cetaceans held in captivity for entertainment or performance in Washington, the state should lead the nation on the question of hemming in these creatures. "These animals that swim thousands of miles should not be put into a fish tank; it's unacceptable," he said. A group representing marine parks told senators the proposed legislation cast a pall on facilities where the public can see orcas and be inspired to support their conservation. "It (the bill) discounts and delegitimizes the important role that zoos and parks perform every day," said Kathleen Dezio, head of the Alliance of Marine Mammal Parks and Aquariums. The Senate Committee on Natural Resources and Parks heard almost an hour of testimony on the ban relating to killer whales, or orcas, and other cetaceans such as dolphins and porpoises, without scheduling a vote on the measure. The legislation would need the approval of members to be sent to the floor for a vote. Animal activists worried about the effects of captivity are behind a push to free Lolita, a 7,000-pound (3,175-kg) killer whale that has lived at the Miami Seaquarium for 44 years in one of the smallest tanks housing orcas. Lolita was captured in 1970 about 50 miles northwest of Seattle, according to People for the Ethical Treatment of Animals, which successfully petitioned for her federal endangered listing earlier this week, paving the way for her possible release into the wild.