Killer Whales Target Favorite Fish With Sonar?
Previous research had revealed that some killer whales off the coasts of British Columbia and Washington State (see map) have an uncanny ability for finding chinook salmon, even in months when chinook are vastly outnumbered by other salmon species such as coho and sockeye.
"Chinook salmon have a higher concentration of [fat] than any salmon species, and apparently killer whales like that," said study co-author Whitlow Au, a bio-acoustician at the Hawaii Institute of Marine Biology.
(Related: "Wolves Prefer Salmon to Deer?" [September 3, 2008].)
Echo Patterns
Like other porpoises and whales, killer whales, or orcas, emit high-frequency clicks that are reflected back when the sound waves strike an object.
The animals use sonar information to navigate, hunt, and communicate in murky waters.
But Au speculated that killer whales also use natural sonar to select specific types of prey.
To test this idea, Au and his team used simulated echolocation clicks resembling those of wild killer whales to measure the echoes produced when the sound waves bounced off the bodies of three kinds of salmon.
