Another dolphin has died at SeaWorld — and her death shines light on the sad plight of one of SeaWorld's least-known animals.

Betsy, a 33-year-old Commerson's dolphin, passed away just days after being transferred from SeaWorld San Diego to SeaWorld's Aquatica park in Orlando, the company announced on Monday. She was the fourth marine mammal to die at SeaWorld since June.

She stopped eating after arriving and appeared to have a "gastrointestinal issue" before her death, SeaWorld said.

Betsy, who had lived in San Diego since being captured from the wild as an infant, had made the move with two other Commerson's. And though she passed away at a mature age — an exception among the many premature deaths at SeaWorld — people are questioning whether the recent relocation contributed to her death.

A Commerson's dolphin on display at SeaWorld San Diego several years ago. Flickr/lori05871

"That was a poor husbandry decision," Naomi Rose, Ph.D., a marine mammal scientist with the Animal Welfare Institute, told The Dodo. She added that, while SeaWorld frequently refuses to move its orcas to sea pens on the basis that they're too old and couldn't handle the move, they had no problem shipping the geriatric Commerson's across the country.

"Why did they move her?" Rose said. "Unless it was imperative for her welfare, it was a bad idea."

But Betsy's death is just the latest in the long string of deaths that defines SeaWorld's experience with the small, black and white Commerson's dolphins.

Back in November, The Dodo spoke to Sarah Fischbeck, a former SeaWorld diver, who said of all the animals she saw during her time at the company the fate of the little-known Commerson's dolphins was the saddest. "The reason you don't know about it is why they're suffering the most," she said.

Betsy was one of 12 Commerson's dolphins captured from the wild in 1983, when she was just a few months old. While SeaWorld originally hoped to make the playful dolphins their new stars, it was a disaster from the beginning. "It was like the standard of what not to do with Commerson's dolphins," Fischbeck said. "It's heartbreaking."

A Commerson's dolphin on display at SeaWorld San Diego several years ago. Flickr/bfurlong

Half of Betsy's group was dead within a year, some of them within days. Around 2000, SeaWorld San Diego sent a group of four young Commerson's who had been born at the park to a now-closed SeaWorld Ohio location. All four were dead within a year.

In 2004 SeaWorld brought in another wild-caught Commerson's from Germany. At 30 years old, Jogi was the only survivor of a group of 10 Commerson's taken from the wild, and had survived decades in captivity. Once at SeaWorld, he died within months.

The company tried to breed the dwindling wild-caught population, but artificial insemination didn't work well "because when they'd go to jack them off they'd get urine and semen samples, and the urine would cancel out the semen," Fischbeck said. The natural births were equally disastrous. Some were stillborn; others lived just a few years.

By 2008, they had seven left, Fischbeck said. SeaWorld sent four males to their Aquatica park in Florida; in 2014, two of them died within weeks of each other.

"In less than 30 years they've killed off 20 Commerson's dolphins," Fischbeck said. "The average lifespan at SeaWorld is 8 years."

By the end of Fischbeck's time at SeaWorld San Diego, Betsy had only two companions left: Juan, the only other survivor of the 12 wild-caught Commerson's, and Ringer, Juan's daughter.

Since the park had sent the viable mates for Ringer to Orlando, she began to mate with Juan. "While working there I saw two of her births," Fischbeck said. "One died shortly, like in two to three days. The other was stillborn. It was her father's daughter."

A pod of Commerson's dolphins in the wild. Flickr/ravas51

But SeaWorld's only concern was money — and the Commerson's weren't bringing it in. "They can't really train them [because they're so high-energy]," Fischbeck said. "They can't make money off them … The three remaining weren't popular. People weren't familiar with them, people didn't care."

At one point, Fischbeck said, SeaWorld tried to mix the Commerson's in with the belugas — despite the fact that they're from different hemispheres. But the belugas quickly began to take out their frustration at captivity on the smaller Commerson's.

"The belugas were super aggressive towards them," Fischbeck said in November. "So they threw them in the back pool and that's where they are now."

As of the end of last year, Betsy and the other Commerson's were living in a tiny 15-foot-deep tank at the back of the park, hidden from the public's sight "because they don't make any money," Fischbeck said.

She added that, after the long string of misadventures SeaWorld's had with its Commerson's, most people didn't even know the animals existed.

"[They're] literally swimming in a concrete box. That's their life," Fischbeck said. "They're just so hush-hush about it because these three dolphins are shoved in the back and that's where they'll spend the rest of their days."

A Commerson's dolphin on display at SeaWorld San Diego several years ago. Flickr/bfurlong

It turned out Betsy didn't die in that tiny, hidden tank — though the end result was sadder than expected. Though Betsy died 3,000 miles away from SeaWorld San Diego, her last view was of the boring concrete walls she stared at for more than 30 years.

"She was with her caretakers and two companion animals in an off-exhibit medical pool in the animal habitat at Aquatica when she died," SeaWorld said in a statement. "Betsy was part of our family for more than three decades and will be greatly missed."

Though there are still questions around Betsy's death, they'll probably never be answered, and the circumstances will likely remain just as private as much of her existence was.

"Did moving her contribute to her death?" Rose said. "I have no idea and I assure you, we will never know, because no matter what the necropsy shows, SeaWorld will not report it honestly and transparently."

And as for Betsy's companions? According to the Orlando Sentinel, Juan and Ringer are now in Orlando — but still tucked away in a tiny concrete pool behind the scenes.

You can read more about Fischbeck's experiences here.

Staff reporter Sarah Schweig contributed reporting.