The recent killing of a gorilla in the Cincinnati Zoo serves as a stark reminder of the safety lapses—for animals and humans alike—that continue to affect zoos worldwide, including in the United States.

Officials at the Cincinnati Zoo on Saturday shot and killed Harambe, a 17-year-old western lowland gorilla, in an effort to protect a young child who had fallen into the enclosure.

Harambe’s death comes at a time when each gorilla life is vital: Western lowland gorillas are critically endangered, numbering fewer than 175,000 in the wild. There are about 765 gorillas like Harambe in zoos worldwide, 360 of which are members of a captive breeding program.

Since 1990, animals died during escapes or attacks 42 times in U.S. zoos accredited