This is NOT related to the Hobbit or LOTR storyline in any way!
It was a calm afternoon. The hobbit and dwarves couldn't snack on anything since the Wargs have stolen their food and ponies. However, Bilbo went into the forest and found a pole. He attached it to a stick and "invented" the fishing rod. It was the most convenient way to gather lunch. He also found wood for a fire to cook the fish.