SEATTLE - When a whale eats a salmon, where does the salmon come from? Finding out the answer can tell scientists which stocks are the most important for maintaining and even growing the population of local Orcas that have been listed as endangered since 2005.

These so called "killer whales" are members of J, K, and L pods that spend much of their time in the waters of Washington and southern British Columbia. It's not unusual to see them in Puget Sound, but they spend much of the summer in the San Juan Islands.

Unlike transient Orcas, which eat other marine mammals, the Southern Residents dine almost exclusively on fish. And the fish at the top of their menu is the King, or Chinook Salmon...and it turns out most of those, some 90 percent come from the Fraser River in British Columbia.

The whales are showing a bit of a comeback with some recent births, but their numbers are still fewer than 90 animals. Food stocks and pressure on Chinook Salmon stocks because of things like pollution and development among the reasons why, in 2005, the National Marine Fisheries Service pushed for their inclusion on the Endangered Species List.

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