Should whales and dolphins be allowed to live and breed in captivity in zoos such as the Vancouver Aquarium? It's a hot-button question that has become very political, but it's not just politicians that have opinions — marine mammal scientists also have lots to add to the debate.

Vancouver's park board, which licenses the Vancouver Aquarium, is currently reviewing the facility's whale and dolphin program. It is holding a third public meeting on Thursday following the release of a staff report on the aquarium's operations.

The report was commissioned amid a growing debate about the program, which includes two beluga whales, two Pacific white-sided dolphins and two harbour porpoises.

Since 1996, the board and the aquarium have agreed not to keep wild-caught whales and dolphins except for those that were rehabilitated and could not be released. But the breeding of captive animals is still allowed.

The debate heated up in May, when a prominent scientist (albeit one who is not an expert in whales and dolphins) called for an end to the aquarium's breeding programs.

In May, chimpanzee researcher and animal rights activist Jane Goodall called captive beluga breeding programs "no longer defensible by science" and asked the board to phase them out.

Here are some questions that have come up in the debate, from Goodall and others, and what some B.C. marine mammal scientists have to say about them.

How healthy and long-lived are whales and dolphins in captivity at places like the Vancouver Aquarium?

Andrew Trites, director of the marine mammal research unit at the University of British Columbia and a research associate at the Vancouver Aquarium, told CBC Radio that the welfare of whales and dolphins "is equivalent, in terms of life expectancy, to what we find in the wild."

However, Dave Duffus, professor at the Whale Research Lab at the University of Victoria's department of geography, says he doesn't think life expectancy is a good measure of well-being for whales and dolphins.

"It's just a numbers game," he said, adding that the animals' quality of life is more important.

Duffus added that when it comes to physical health, whales and dolphins in aquariums are more likely to have problems with their digestion, teeth and behaviour than their wild counterparts.

He added that physical ailments are a particular problem for orcas or killer whales (which the Vancouver Aquarium no longer keeps) because they're huge animals that travel long distances in the wild and are "built to move."

"No matter how big your aquaria are, how well set up it is, it's still significantly different than their natural setting. It causes lots of problems."

Trites agrees that orcas should not be kept in captivity, primarily because of their unique social behaviour.

How happy are whales and dolphins in captivity?

Trites, whose own research specialty is seals and sea lions, says that the animals at the Vancouver Aquarium appear happy.

"Certainly by measuring stress levels, they seem to be very laid-back, relaxed, co-operative, stimulated," he said, "and I think that in many respects, they are living very fulfilling lives."

Duffus said that from a scientific viewpoint, the mental state of a dolphin or whale is a "black box."

"We interpret things about them, but we have no way of verifying what's going on in the brain."

He said there is some evidence that whales and dolphins can become "depressive" in a sensory-deprived environment such as an aquarium.

Is it possible to build suitable tanks for whales and dolphins?

Trites acknowledges that some marine mammals are too big to keep in captivity, but called beluga whales "fairly small" and said they tend to live in a smaller amount of space, even in the wild.

However, other researchers expressed concerns about the acoustic environment in tanks at places like the Vancouver Aquarium.

Paul Spong, co-director of the Orca Lab on Hansen Island, said whales and dolphins "live in a world of sound." They use sound to communicate and in some cases, use a form of echolocation or sonar to "see" and hunt for food, as bats do.

"When you put them in a concrete tank, you deprive them of that sensory experience, and it's very, very important to them," he told CBC Radio's B.C. Almanac.

Duffus had a similar opinion about the acoustic environment in aquarium tanks for whales, saying, "It's fairly cruel and unusual for the animals to be in that situation."

Do captive-bred whales and dolphins do better in captivity than those bred in the wild?

Trites said there isn't much research about whether captive-bred animals do better in captivity, but scientists suspect that is the case, since captivity is all they've ever known.

Captive breeding also has the advantage that it doesn't affect wild whales and dolphins the way capturing a member of their pod might.

Trites added that it's not easy to prevent captive animals from breeding.

Duffus said there is some evidence from Sea World, which keeps both captive and wild-caught whales, that captive-bred whales do better in captivity. However, he said, breeding programs often lead to problems such as premature births and inbreeding. In his view, those disadvantages outweigh the possible benefits.

Do baby whales die more often in captivity?

In Goodall's letter, she alleged that there are "high mortality rates" in beluga whale breeding programs at the Vancouver Aquarium and at Sea World.

While Duffus is opposed to breeding belugas in captivity, he said beluga calves can die from many causes both in the wild and in captivity, so it may be impossible to tell what role captivity might play.

How important is research on captive whales and dolphins for the science and the conservation of wild whales and dolphins?

Trites says the research is very important. In the controlled conditions at the aquarium, he said, scientists can do things such as:

Measure an animal's metabolic rate to find out how much food it needs.

Develop ways to reconstruct what wild whales and dolphins are eating from their fecal samples.

Develop technologies such as tracking technologies to study wild whales and dolphins.

"I think a lot of people don't fully appreciate that it isn't possible for biologists to simply to sit on a beach and look at an animal out in the wild, or following it on a boat to learn the sorts of things we need to know in order to help further their conservation," he said. "The foundation of science is conducting studies under controlled conditions and that's what the animals we have here in Vancouver allow us to do."

He added that the alternative for many of the studies would be capturing animals and holding them in pens, but the data wouldn't be as good because the animals are stressed.

Duffus, who studies whales in the wild, disagrees that research in aquarium conditions is crucial.

"All research is valuable at some point in some situations," he said, "but the kind of research that we need on marine mammals in Canadian waters, if you made a priority list of stuff — [what] comes out of aquaria in captive settings is at the bottom."

If breeding whales and dolphins is banned, should aquariums maintain the ability to rehabilitate wild whales and dolphins that have been injured?

Spong says he has no problem with an aquarium having tanks to allow the rehabilitation of injured animals with the idea of releasing them to the ocean. "To me, that's fine."

But Duffus is uncomfortable with even that idea.

"Like anyone, I hate to see an animal in distress or injured, especially when it's caused by a human activity," he said. But he added, "I'd prefer to see animals live their lives and die in the natural ecosystems that they're part of."