IN the video "Blue Planet" put together by Richard Attenborough and shown on the Discovery Channel, there is great footage of salmon attacking a bait ball and slashing with their tails. It is very well documented that salmon attack from beneath and come back around after the intial slashing to pick up the stunned bait fish. In other videos salmon can be seen following a bait for a long time before attacking from the side...that is probably why so many herring come back to the boat with bite marks in between the hooks.