The big question facing Baltimore’s National Aquarium — whether to keep Atlantic bottlenose dolphins in the amphitheater pool or release them to an ocean-side sanctuary — is the latest twist in the decades-long evolution of American zoos and aquatic attractions from circus-like menageries to portals into the natural environment.

Much of the change is driven by emerging scientific evidence that shows the advanced intellect of marine mammals compared with species such as sharks and puffins. That has led officials at the 33-year-old Inner Harbor anchor to rethink the dolphin display as they seek to emphasize conservation.

The debate resonates among scientists, activists and some members of the public who see the consequences of containing dolphins — which sometimes show signs of chronic stress and self-mutilation — as a crisis of conscience.

It’s also a high-stakes issue for the aquarium — and Baltimore. The aquarium, where adult tickets run upwards of $30, risks losing visitors and revenue if the popular dolphins are moved. And Baltimore would be hurt by any dropoff at the aquarium, whose 1.3 million annual visitors make it one of the city’s biggest tourist destinations.

Pikesville resident Bunny Bernstein said that when she took her grandchildren to the aquarium five years ago her “stomach got upset” by the acrobatic stunts the animals were performing.

“I couldn’t stand to watch it,” the 71-year-old said. “I’ve never been back. “I just think it’s terrible. It’s like the elephants at the circus.”

In recent years, documentaries such as “Blackfish,” a CNN film about orcas in captivity and the 2010 killing of a Sea World trainer, and “Keiko: The Untold Story of the Star of Free Willy,” have given the debate more prominence among the public.

Scientists and activists say that if the National Aquarium moved the dolphins to a sanctuary, it would be the first major institution to take such a step. Many still believe, however, that putting animals on display in zoos and aquariums brings a significant societal value, especially for inspiring children.

“What I am really worried about is, kids are getting totally separated from the natural world,” said Temple Grandin, a renowned animal science professor at Colorado State University and the subject of a 2010 HBO biopic.

“Kids get interested in things they get exposed to. I am worried that if people don’t get exposed to dolphins, they are just not going to care about them.”

The National Aquarium’s move comes even as attractions in other cities have spent millions of dollars in recent years to develop bigger dolphin shows. The Georgia Aquarium in Atlanta, for example, touts its AT&T Dolphin Tales show’s actors, costumes and an original score “performed and recorded by a 61-piece orchestra at Sony Studios in Hollywood.”

The National Aquarium announced last week that under the direction of CEO John Racanelli, who came to Baltimore in July 2011, a team of consultants is evaluating the dolphin attraction’s future role.

The process, called BLUEprint, is focused on exploring how the aquarium can show the connection between humans and the environment, and motivate action toward preservation.

“We’re trying to open people’s eyes to the ocean and the aquatic places in their lives,” Racanelli said Friday. “That’s our life support system.”

BLUEprint will also assess the aquarium’s presence in Washington, perhaps with the creation of an “ocean embassy,” and re-imagine the aquarium experience with more cohesive exhibits. Specifically, aquarium leaders will decide whether to relocate the dolphins, create a Chesapeake Bay wetland exhibit in the water between the piers and develop collaborations with the Smithsonian Institution.

Aquarium officials have not determined potential locations for a dolphin sanctuary, but Racanelli said one would have to be created in a warmer climate to suit the marine mammals.

No timeline has been set for their decisions.

The aquarium eliminated its 20-minute dolphin performance show about two years ago. Officials said at the time that they wanted the exhibit to offer something new and different, while increasing the number of visitors who could engage with the dolphins.

Now, the eight Atlantic bottlenose dolphins in its care — including 5-year-old Bayley and 42-year-old Nani — can be observed continuously in the amphitheater, where the public can also interact with trainers.

The dolphins have always been a big draw, but many aquarium visitors come for the overall experience, Racanelli said. The key to the BLUEprint process, he said, is ensuring that the aquarium maintains “our roots as a catalyst for the Inner Harbor.”

Mayor Stephanie Rawlings-Blake said the aquarium is part of her plan for a thriving city.

“The aquarium is an iconic institution that has continued to grow and attract thousands of visitors to Baltimore,” she said in a statement. “Its success is one of many elements Baltimore has that supports my goal of growing the City by 10,000 families, because to grow a city you have to both attract new residents and give those already here more reasons to stay.

“The aquarium achieves those goals and much more, including generating millions of dollars in economic growth to our city and support for thousands of jobs.”

Racanelli said he would never envision an aquarium devoid of live animals. “We try to balance the needs of the animals with the need for the public to be able to build emotional relationships with animals, in a time when increasingly fewer and fewer people have any natural contact with animals.”

Still, he noted that marine mammals, including dolphins and whales, are large-brained, cognitively advanced species. Other species, such as some exotic birds and octopuses, show “remarkable flashes of cognitive capacity,” but nothing compared to higher-order mammals, he said. Sharks, meanwhile, don’t exhibit play behavior or appear to have abstract thinking.

“That’s why there is a strong debate around the life and times of dolphins and whales,” Racanelli said.

Carole Michaelson, a 71-year-old Hanover resident, used to take her daughter to see the dolphin show and now takes her 8-year-old grandson to the aquarium every year. Michaelson, who feels the animals have something of a healing effect on humans, believes it would be a major loss if they no longer performed.

“To be able to get out there and see them and get up close is still a thrill,” said Michaelson, who grew up in Bethany Beach and remembers often seeing dolphins in the wild.

Michaelson said she would still make the annual trip to the aquarium if the dolphins were moved, but quickly added that the experience wouldn’t be the same.

People for the Ethical Treatment of Animals, known as PETA, says the public should view animals in their natural habitat or on documentaries such as the series “Planet Earth.”

“Captivity can’t even begin to replicate the natural environment,” said Jared Goodman, director of animal law for the PETA Foundation. “Zoos and aquariums claim to promote education. The only thing they teach is, it’s OK to have these animals locked up in these enclosures where they are bored, lonely and deprived of all control of their own lives.”

Alfred Beulig, a biology professor at New College of Florida, said there’s no scientific reason dolphins shouldn’t be held in captivity. But there are reasons why aquariums must take extra care if they do keep them. As mammals, dolphins’ brains work differently than those of other animals, and that requires a different environment than is provided for, say, sharks.

“They’re a social animal. If you deprive them of social stimulation you have to compensate for it somehow,” Beulig said. “The key question here is: ‘When you keep dolphins are you adhering to their specific requirements and predilections or not?'”

But Beulig, who generally supports animal exhibitions if they raise public awareness, also stressed that people shouldn’t ascribe human characteristics to dolphins or assume that they’re “smarter” than other animals.

“People automatically say, ‘Well, you’re depriving a dolphin of its freedom,’ but this is a concept that they don’t necessarily have,” Beulig said. “The animal rights groups make a fatal flaw when they start reading into the deep thoughts of a dolphin.”

Diana Reiss, a professor at New York’s Hunter College who for years conducted research at the National Aquarium, said the Baltimore institution is again confronting the question about how zoos and aquariums can provide the best possible settings for animals. That discussion, she said, has been framed by the emerging science on various species.

Science now clearly shows dolphins to be highly social and complex, Reiss said. She helped to discover about a decade ago that dolphins, like Asian elephants, recognize themselves in the mirror, a sign of self-recognition that is rare among animals.

“We don’t do elephant shows or gorilla shows,” she said. “There has been a real evolution of zoos from more of menageries to a place where animals can roam in open spaces.

“We’ve changed the way we’ve housed so many other animals, but not dolphins and beluga whales and orcas. It’s a very important thing that we’re saying, ‘Perhaps concrete pools aren’t the way of the future.’ No matter how big we can make a pool, it’s concrete and it has certain acoustics.”

Reiss says aquariums have a role as a learning tool that can prompt the public to take action ensuring dolphins are protected in the wild.

The goal should be to find an environment for dolphins that is more naturalistic and more of a sanctuary, but still allows people to stay connected to them, she said. One idea is to stream a live feed from underwater cameras in the sanctuary into the aquarium or allow a virtual dolphin to teach observers about its life, she said.

Reiss, who will be part of a Dolphin Summit for experts at the aquarium this month, added, “We need to find a way to address the needs of the animals, because it’s their welfare we have to keep in mind.”

Baltimore Sun reporter John Fritze contributed to this article.

Photo Credit: Tilikum in a scene from "Blackfish," a Magnolia Pictures release. Suzanne Allee / Magnolia Pictures/MCT