The National Aquarium in Baltimore, Maryland, will move all of its eight dolphins to a sea sanctuary by 2020, PBS NewsHour reports. Two years ago, the facility announced that it was considering the move, citing concerns that it was cruel to keep such intelligent animals in captivity. The aquarium’s CEO, John Racanelli, reiterated those concerns in an op-ed published today in The Baltimore Sun . “Emerging science and consultation with experts have convinced us that dolphins do indeed thrive when they can form social groups, have opportunities to express natural behaviors, and live in a habitat as similar as possible to that for which nature so superbly designed them,” he wrote.

The move comes as scientists and the public increasingly struggle with the ethics of keeping cognitively advanced animals like dolphins and chimpanzees in captivity. Just last month, a group of scientists and animal advocates unveiled plans to build a sea sanctuary for captive orcas. Racanelli writes that the National Aquarium is still researching what the proposed sanctuary will look like, but that whatever it builds will be much larger than the facility they currently live in and that the animals will be cared for by humans for the rest of their lives.