Endangered Killer Whales Prefer Eating Chinook Salmon In Summer

Do you have a favorite summer meal? Killer whales do. Researchers from the National Oceanic and Atmospheric Administration (NOAA) have confirmed an endangered population living in the Pacific Northwest primarily feast on salmon during the summer, a fact that may lead to improved targeted conservation practices.

"Using an independent method, we have confirmed that salmon, and especially Chinook salmon, are by far the dominant component of this whale population's summer diet," Michael Ford, one of the study researchers from the NOAA, said in a news release. "The study helps to solidify our understanding of the ecology of this endangered population, and will be useful for continuing to prioritize recovery efforts."

In the latest study, researchers analyzed fish DNA present in feces collected from killer whales (Orcinus orca) - this type of analysis tells researchers exactly what the whales ate and when. Previously, knowledge of the animals' diet was solely based on observations of prey consumed at the surface, so researchers were interested to see what else these whales might be snacking on.

The fecal samples were collected between May and September of 2006-2011, from the whales' summer range in the Salish Sea in the Pacific Northwest. Researchers genetically sequenced 175 poop samples, which revealed nearly five million individual sequences that were then compared to fish living within this range in order to determine the whale's potential diet.

In total, researchers found salmon accounted for more than 98 percent of the total genetic sequences. Of the six potential salmon species in the area, Chinook salmon made up 80 percent of the sequences, followed by 15 percent coho salmon - however, in the later summer coho salmon increased to 40 percent of their diet.

This find, recently published in the journal PLOS ONE, support earlier results based on surface prey remains.

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