You might like to consider the way in which the story places the narrator in an impossible position where he has to make a choice between two things that he equally desires. The way in which his attraction towards Sheila Mant, his older neighbour whom he has long admired, and his desire to catch the bass is balanced creates a conflict within the narrator that is only resolved towards the end of the story. Note how important this conflict is for him:

Behind me, I could feel the strain of the bass, steadier now, growing weaker, and this was another tug on my heart, not just the bass but the beat of the river and the slant of the stars and the smell of the night, until finally it seemed I would be torn apart between longings, split in half.

Note the way in which the narrator is forced to make a choice between Sheila Mant, whom we recognise as being a vain and self-absorbed girl, and something that is intrinsically part of him: nature and the desire to fish. He has to choose which one he will catch, and although he makes the wrong choice in this story, the ending shows that he has learnt his lesson about making wise sacrifices and realising who he is and making choices based on his identity.