Animal trainer Deirdre Weadock has worked at the National Aquarium long enough to have seen her share of life and death, but she'll tell you this has been the roughest week of her career.

Losing one dolphin, then another, within days.

"You can't really describe what this feels like to other people," Weadock said Sunday, her voice breaking. "I guess any parent can relate."

On Saturday night, the second of the aquarium's two calves died in the arms of the aquarium's medical workers as they tried desperately to save her.

The first had been found dead in the pool on Tuesday.

The loss of the two bottlenose dolphin calves is a blow to the Inner Harbor attraction, where officials had begun only this month to promote them. And it's one that officials say almost surely precludes any further dolphin breeding in the aquarium's near future.

"We're all exhausted and emotionally spent," said Sue Hunter, the aquarium's director of animal programs. "We want to focus on the animals because they feel a loss too."

Though the aquarium canceled dolphin shows on Sunday so that staff could mourn, officials said it would be business as usual Monday — even if trainers and staff are unlikely to have gotten over such a traumatic week.

The calves were born in April to Maya and Spirit, half-sisters who are both 10 years old and first-time mothers. Spirit's calf arrived on the morning of April 14. Maya's was born two weeks later.

Because the National Aquarium has no male dolphins of breeding age, Maya and Spirit were impregnated by a male named Chinook brought to Baltimore from Chicago's Brookfield Zoo just for the purpose.

Both in the wild and in captivity, mortality rates for dolphin newborns are perilously high — about 33 percent. The aquarium started the calves on 24-hour watch, with staff staying with them constantly to monitor their breathing, their nursing, their fecal output. Any whiff of abnormality was a cause for alarm.

Early on, staff were concerned about Maya's confusion with nursing. She didn't get it, and figured it out only after coaching from one of the other female dolphins.

But with that scare over, the newborns seemed to thrive, and staff allowed themselves to breathe a bit more easily.

The calves — one female, one male— learned to swim, filled out, began to vocalize with clicks and "eeps" and started to exhibit signs of personality. Spirit's calf, the female, emerged as the plucky one, curious and independent. Maya's calf was timid, sticking close to his mother's side.

The aquarium began proudly publicizing the calves earlier this month, and the staff tried to work them into the popular dolphin show in a way that could show them off, but keep their newborn atmosphere as tranquil as possible.

Their answer was a "lite" version of the dolphin show — one in which they took the usually boisterous, splashy crowd-pleasing spectacle and ratcheted the energy level way down. They hushed the music, allowed fewer visitors in at a time, and substituted video of the babies for most of the noisy acrobatics.

For Weadock, who helped raise Maya and Spirit, it was particularly thrilling to watch the two come into their own as mothers.

"It's pretty amazing to watch them," she said. "And just watching these two [calves] grow. You could see how much they developed each day."

Which is why the staff was so stunned to find Maya's calf dead Tuesday morning.