The seas off Egypt, Greece, and Scandinavia were important sources of food and had been harvested since prehistoric times. The technology of boats and further improvements in nets, navigation, boat capacity, traps, etc., all improved the efficiency and production of fishermen. We know from wall murals that Greek fishermen were taking bluefin tuna in Mycenaean times, a thousand years before the classical Greek age. The Norse were also great sea hunters and fishermen. Salted and dried fish could be stored for many months and was an important source of protein before the days of refrigeration.