can can-opener opener tin-can brisling bristling calcium canned clupeidae edible European-sprats fatty-acids fish food golden health healthy heart-healthy herring-family herring-like marine-fish nonperishable nutrient-rich nutrients nutritious oil oily-fish omega-3 packed polyunsaturated portable potential self-contained-food skipper small smoked sprats sprattus-sprattus tightly-packed tin tinned tins vitamins empty hoard meat metal supply tenable