Gray whales primarily eat small crustaceans and plankton, which they filter from the sediment on the ocean floor. They do not eat fish, including coho salmon.
Therefore, gray whales do not eat coho salmon.
Do gray whales eat coho salmon?
Gray whales are baleen whales, meaning they have baleen plates instead of teeth. Baleen plates are made of keratin (the same material as human hair and nails) and are used to filter food from the water.