A fishing rod is a tool used to catch fish. One catches the fish with the rod by either casting of angling. A fishing rod is comprised of a long flexible rod or pole, a fishing line and a hook or lure.
Starfleet issue rods are made of metal or another artificial material and have a fishing reel to pull up the fish. (JB: "Just Between Enemies") Improvised rods can be made of a variety of materials, natural or artificial. In the case of an improvised rod a flexible branch is most commonly used. Starfleet survival packs include materials for use of constructing such a rod, and provides hooks, lures and fishing line. (JB: "Just Between Stars")
In 2374 captain Janeway and Seven of Nine were forced to improvise a fishing rod for angling from a branch and some fishing line after crashing on an uninhabited planet. Seven uded the makeshift rod to catch fish in a small stream. (JB: "Just Between Stars")
In 2377 commander Chakotay took Icheb with him on a spiritual journey on an uninhabited planet during his leave of absence. He thought the boy how to cast for fish in a river there. They used Starfleet issue fishing rods with a fishing reel to catch the local salmon-like fish. (JB: "Just Between Rest & Recreation")