Four short lines, and the whole poem is a list of reasons for standing at the water with a line out. The speaker fishes "in the raw present," which suggests a moment stripped of distraction, with nothing between them and what is happening right now. "Raw" also hints at something unpolished, even a little uncomfortable, as if the present is not always gentle.
Then come three purposes, joined by "and." The first is practical and humble: to be "serviceable," meaning useful, perhaps to others or simply to the world. The second is to pray, which turns the act of fishing into something quiet and devout. The last one is the surprise. The speaker fishes "to be," and nothing more. After usefulness and prayer, existence itself is the goal.
The mood is calm, patient, and spare. The short lines feel like waiting at the water's edge, and the poem ends on the simplest verb there is, leaving a feeling of stillness and quiet gratitude.