The group of orcas known as the Southern Resident Killer Whales was listed as an Endangered Species by Canada in 2001 and the United States in 2005, as a result of a sharp drop in their population. In 1996, there were 97 whales in this group; in 2001 there were only 78. Researchers were extremely worried that this small number of whales might not be able to reproduce quickly enough to maintain their population. As of December 2010, the Southern Resident population has increased to 86 individuals, but this is still not considered a stable population.
There are three main threats to this endangered population of killer whales:
Decreasing availability of their prey, mainly salmon
Increasing toxic pollutants in the marine environment
Effects from vessels and underwater sound
Many studies and conservation efforts are currently underway to save these endangered whales.