My recent experience in the canned tuna aisle at the store went something like this: me, immobile, studying the cans and pouches with their shiny labels, wondering which kind of tuna I should be eating again. Albacore? Yellowfin? Does it matter? Actually, it matters a lot, seafood experts say, given how much canned tuna we eat (2.2 pounds a person annually, according to the National Fisheries Institute).