It’s been 26 years since the Exxon Valdez supertanker slammed into a reef, releasing nearly 11 million gallons of crude oil and destroying hundreds of thousands of animals, from sea otters to bald eagles, in and around Alaska’s Prince William Sound.

You’d think nearly three decades would be long enough for the wildlife to recover, but some populations took a harder hit than others. Take killer whales, also known as orcas.

They’re the subject of a new National Geographic investigative documentary produced by reporter J.J. Kelley exploring the effects of the Exxon Valdez spill on this highly intelligent animal. “News always goes in and covers the immediate,” Kelley says, “but what about the long-term fallout?”

Two pods of orcas were caught up