VICTORIA, British Columbia, Nov. 17 (UPI) -- U.S. and Canadian researchers said killer whales can hear the difference between Chinook and other types of salmon.
Researchers said the whales, which swim the waters off British Columbia and Washington state, used echolocation to sort the Chinook from the Coho and Sockeye salmon. The whales apparently prefer Coho because it is a fattier fish.
The researchers found "the echo structure from similar sized but different species of salmon were different and probably recognizable by foraging killer whales," bioacoustician Whitlow Au of the Hawaii Institute of Marine Biology said in a release.
Marine ecologist John Horne of the School of Aquatic and Fisheries Science at the University of Washington, Seattle, said the secret to the killer whale's ability to choose their favorite entree is the salmon's swim bladder, which controls the buoyancy of the fish and is responsible for most of the reflected sound energy, Canwest News Service reported Monday.
The report, presented last week at a recent meeting of the Acoustical Society of America in Florida, said the swim bladder on a Chinook salmon is half the size of other salmon species.
