Weather-Beaten Journal

When used, the Weather-Beaten Journal teaches the player Find Fish, the ability to observe fishing spots on the mini-map in the same manner as the hunter's ability to track beasts. This is the only way to gain the Find Fish ability.

Source
Weather-Beaten Journal is a World Drop looted from within containers found when fishing, most commonly from pools such as Floating Wreckage.

It can be found inside any container gathered from fishing, including amongst others. It can also be found inside the daily fishing quest reward,.

In order to see the Weather-Beaten Journal in the container being looted, the character looting the container must have at least apprentice Fishing training (must have at least 1 skill point in the Fishing skill)