A tasty alternative to pouched tuna are the Gourmet Choice™ cans. They are pop-tops so are trail friendly. The two varities packed in olive oil are Yellowfin Tuna in Roasted Garlic or Lemon Dill.
Finding tuna in olive oil isn’t always easy – due to consumers eating water packed tuna to watch calories/weight. The sad thing is tuna tastes so much better if packed in oil – and as a bonus no need to pack in extra olive oil. They also produce a plain version packed in oil as well, which is quite nice.
Find them in the tuna section of most grocery stores. Expect to pay $2 to 2.70 or so per can. Not the cheapest, well worth it as a treat though.