Picked up my new canner yesterday and can't wait to can them.
Follow very carefully the instructions for pressure canning. Tuna takes and hour and forty minutes at eleven pounds pressure. If it drops below ten pounds pressure don't resume your time until it reaches the correct pressure again. After your jars have cooled remove the rings and lift the jars by the tops to be sure the jars have sealed. Ones that haven't sealed should be refrigerated and eaten immediately.