The Alaskan Residents are a fairly large population consisting of 32 separate pods and one "grey box" group of residents that have yet to be sorted into any pod. They, like all other resident populations, are very vocal and are often heard over hydrophones, even if they aren't seen. They are fairly surface active and share the behavior of beach rubbing with the Northern Resident Community. It is currently unknown where the Alaskan Residents picked up the beach rubbing, but they and the Northern Residents are the only populations that have been documented participating in the behavior. On March 24, 1989, when the vessel Exxon Valdez spilled 53.1 million gallons of oil into Prince William Sound, AB pod swam through it, resulting in 16 whales going missing and being confirmed as deceased by 1990. AB Pod continues to struggle to this day and their numbers are lower than many of the other pods.