Updated July 27, 2017 12:02:43

Photo: Kyara was the 40th orca to die under SeaWorld's care and the third to die in the past 18 months. (Twitter: SeaWorld)

The last killer whale born in captivity under SeaWorld's controversial orca-breeding program has died at the US company's San Antonio park.

Three-month-old Kyara was treated for an infection last weekend, SeaWorld said in a statement, but its health had continued to decline and it died on Monday.

Kyara was the 40th orca to die under SeaWorld's care and the third to die in the past 18 months.

SeaWorld announced the end of its breeding program in March 2016, following years of pressure from animal rights protests and shifting public opinion about orcas being held in captivity, and will also phase out its killer whale performances by 2019.

The backlash intensified after the 2013 release of Blackfish, a documentary critical of SeaWorld's orca care.

A veterinary team will conduct a post-mortem examination to determine the cause of Kyara's death.

The release said it was suspected it had pneumonia, but an official post-mortem could take several weeks.

Following Kyara's death, former SeaWorld trainer John Hargrove, who featured in Blackfish, tweeted: "SeaWorld is insane — continuing to say their orcas are healthy and thriving despite death after death from illness & disease."

Kyara was born to 26-year-old Takara last April but was conceived before the program's end was announced — orca gestation can last up to 18 months.

Orcas expected to remain on display

San Antonio trainer Julie Sigman said in a statement: "Kyara had a tremendous impact on the entire zoological team, not to mention all of the guests that had the chance to see her."

"The heart and support that has gone into caring for her throughout Takara's pregnancy until today has been amazing," she said.

"As animal caregivers we dedicate our lives to these animals, and this loss will be felt throughout the entire SeaWorld family."

Photo: Takara was pregnant with Kyara before SeaWorld announced the end of its program. (Twitter: SeaWorld)

SeaWorld has not collected a wild orca in nearly 40 years, and most of its orcas were born in captivity.

SeaWorld has 22 orcas left in the US, the youngest of whom, Amaya, was born in December 2014.

All the orcas are expected to remain on display and available for researchers for years to come in Orlando, San Diego and San Antonio.

SeaWorld has announced plans to introduce new "natural orca encounters" in place of theatrical shows.

ABC/AP

Topics: animal-welfare, animals, human-interest, united-states

First posted July 27, 2017 10:46:10