The food of the Pacific herring Clupea pallasii consists during the larval stage principally of ova of various kinds with circular diatoms. No food was found in fish less than 9 mm. in length. Postlarvae and fry take the greatest variety of food, Copepoda and Cirripedia larvae being the most important items. Apparently the most readily available of suitable foods is taken. Adults confine themselves to a crustacean diet (except herring ova occasionally), Copepoda and Euphausiacea comprising the bulk of the food, Calanus predominating in the spring and Euphausia during the remainder of the year. Purse seined herring rarely contained any food. Copepoda are on the whole the most important food of the Pacific herring.