Watch: Why killer whales love Chinook salmon

According to researchers, orcas depend heavily on Chinook salmon to ensure a healthy diet which the endangered killer whales trap in waters in California's Sacramento River to Taku river in northern British Columbia.

There are ten species of Pacific salmon with seven that occur in the pacific northwest including Sockeye, Chinook, Steelhead trout and Cutthroat trout, according to the centre for whale research.

Chinook salmon is the largest species with an average size of 13 kg, with the heaviest of them being at least 45 kg. However, it is the least abundant species. Salmons often travel over 30 miles per day during their spawning journeys.

The Chinook salmon has longer lifespans compared to other Pacific salmon.

Researchers gathered data on what the killer whales eat while cruising the outer Pacific coast by analysing the DNA of orca faeces including salmon scales and other remains after the whales finished off the fish. The data pointed towards the presence of Chinook salmon in the killer whale's diet.

Chinook salmons are widely found along the United States west coast including inner Columbia, Oregon coast and northern California coast.