A fourth bottlenose dolphin has died at an East Valley attraction in less than two years.

Kai’s death comes one month to the day after the facility announced the passing of 11-year-old Khloe on New Year’s Eve. Their deaths were preceded by Alia in May 2018 and Bodie in September 2017 .

“We recognize losing four dolphins over the last year and a half is abnormal,” Dolphinaris general manager Christian Schaeffer said in a statement. “We will be taking proactive measures to increase our collaborative efforts to further ensure our dolphins’ well-being and high quality of life.” Schaeffer called Kai’s death a “devastating loss” and said outside experts would assist with an investigation into his and the previous dolphin deaths.

The facility has been open since October of 2016 and has been criticized for housing dolphins in the Sonoran desert since the project was announced.