Do you eat Tinned Tuna?
I've just come across this great, updated, article Sarah Wilson on tinned tuna http://www.sarahwilson.com.au/2010/04/which-tinned-tuna-should-i-buy/ . Interesting reading!
Also if you have any interest in sustainable seafood then you must read Four Fish by Paul Greenberg. It really is a book that will change your outlook. The book website is http://www.fourfish.org and you can buy Four Fish from Amazon.
Life changing stuff!