Energy used by U.S. ships in harvesting seafoods can vary by a factor of more than 100 when the seafoods are compared on the basis of their content of edible protein or line weight. This energy difference bears no relationship to the nutritive value of the food. When protein yield is compared, the energy to harvest some seafoods is in the same range as that needed to grow field crops. There is a large increase in energy consumption after processing, partly because of the small percent of the live weight used for human food.