MYSTIC, Conn. — On her trainer’s command, an alabaster-skinned beluga whale named Naku placed her chin on the deck of her outdoor pool and exhaled several times, emitting a hollow “chuff” sound with each breath. The vapor rose into a petri dish a researcher held over her blowhole.

Those tiny drops contain a wealth of information, it turns out. Researchers at Mystic Aquarium and elsewhere are learning how to use the breath, or “blow,” of whales and dolphins to extract and measure hormones, microorganisms, DNA and the byproducts of metabolism.

Their goal is not only to improve the health of captive cetaceans like Naku, but also to develop a powerful, unobtrusive technique for studying them. While blood is the gold standard in physiological research, it can be hard to obtain — and all but impossible from large whales. Three new studies describe advances in breath analysis, which may prove to be the next best thing.

“I suspect that everything that’s in the blood is in the blow, just at much lower concentration, a little harder to measure,” said Kathleen Hunt, a research scientist at the New England Aquarium in Boston. “All kinds of goodies that we could learn a lot from that we’ve never been able to get from these animals.”