I love canned seafood including tuna. I do try to make ecologically responsible and low-contaminant choices by choosing smaller fishies at least as often as the big guys. Smaller, younger fish are said to be the safer and more sustainable choice, but unless you're eating tons of fish, it probably doesn't matter.
Mostly for me, it's an excuse to check out the dozens and dozens of canned seafood options at the local asian groceries. Before I discovered Smiling fish brand out of Thailand, I never knew sardines and other fish and fish fillets came in so many different sauces (The cans look like tomato paste cans because the fish are packed upright).
You do have to read the labels because some sauces are higher in salt, sugar, calories, fat.... or whatever else you might care about.
Sardines or mackerel in every shade of curry seems weird to the uninitiated at first, but really yummy once you get over the odd factor.
Not so odd anymore though, now that flavored tuna is becoming popular in the US. I love the flavored tunas from familiar brands like Starkist and Chicken of the Sea. Sweet and Smoky is one of my favorites.