The last killer whale bred in captivity under Sea World's controversial orca breeding program died on Monday in the park's San Antonio location.

The orca was a three-month-old calf named Kyara born in April from a park whale named Takara.

According to a press release from the park, Kyara died after complications from an infection that had grown progressively worse over the past few days.

The orca calf received 24/7 monitoring in the days leading up to her death. Sea World veterinarians treated her with antimicrobials and antibiotics, even attempting to feed the whale by hand.

Twenty-two orcas now remain at the park's Orlando, San Antonio, and San Diego parks. The youngest remaining, Amaya, was born in 2014.

The exact cause of Kyara's death cannot be ascertained until a full post-mortem exam is complete, but park officials believe it was likely pneumonia. Bacterial pneumonia was found to be the cause of death for Tilikum, the 36-year-old captive orca that died last Feburary.

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Tilikum is perhaps the park's most famous orca, having killed a trainer in 2010 and been involved with two other deaths in the 1990s. The orca rose to prominence after being featured in the 2013 documentary Blackfish that turned a spotlight on the park's practices.

In a 2016 article for National Geographic, the documentary's co-writer, Tim Zimmerman, wrote that Tilikum suffered from confinement, boredom, chronic disease, and aggression from park orcas and trainers.

According to a 2016 investigation by the San Antonio Express-News, 60 percent of orca deaths at Sea World's three parks were caused by infection. The report also found that, in the past two years, eight whales and dolphins have died at the San Antonio park, and in the past 30 years, 150-infection related deaths occurred at the park's three locations.

In their press release, Sea World maintained that Kyara's infection had not been caused as a result of being kept in captivity. The park continues to monitor the remaining orcas, none of which have yet exhibited signs of illness.

After public outcry, Sea World officially ended its captive orca breeding program in March of 2016, signaling what the park said at the time as a "new direction for the company."

The park's remaining orcas have been born in captivity or were moved into the facilities at a young age. For that reason, Sea World decided in 2016 to keep the remaining orcas at Sea World, rather than release them to the wild, where it's not believed they could survive.

In addition to public outcry, Sea World faced legal challenges to maintaining its orca shows after a 2016 law passed in California banning captive orca breeding. Live shows will be phased out in California, but will still take place in Orlando and San Antonio.

The International Union for the Conservation of Nature tracks the population status of the world's animals, but it does not have a rating for orcas due to their wide distribution and varied population sizes. After human beings, orcas are considered the most wide-ranging mammal species on the planet.