One of Bishop's most subtle strengths is the sound of her poetry. It's not pots and pans clanging, it's more like a gentle breeze through the leaves. You don't really notice the sound unless you pay close attention, but when you finally tune in, you end up loving what you hear.
We count 24 "ands" in this poem. Bishop loves detail, and what simpler way to connect her descriptions than using "and." It keeps the flow going. Look at the opening where Bishop writes, "battered and venerable/ and homely." She could have easily written, "battered, venerable, and homely," but she enjoys the separation and rhythmic unity "and" affords her.
There are also plenty of places where Bishop could have simply made two sentences, but instead joined them with "and" in order to keep the poem moving. For example, "I stared and stared/ and victory filled up/ the little rented boat" could have easily been two separate sentences. Bishop also begins the last sentence with "and" which gives it more oomph than the flatter sounding alternative, "I let the fish go."
Lots of poets use alliteration (the use of the same letter or sound at the beginning of words that are close together) to create some music in their poems, but Bishop is pretty subtle about it. It can sound a little silly when it's overused – think of "Sally sold seashells down by the sea shore." Bishop curbs it some, creating a sense of sonic unity without blasting out your eardrums. Here are some examples: "skin in strips"; "crisp with blood,/ that can cut"; "big bones and the little bones,/ the dramatic reds and blacks." You can see the repeating sounds in each example, but it's not too obvious.
Much like the subtle alliteration, Bishop pairs words (or places them very close together) that sound very much alike – almost like rhymes, but not quite. Want an examples? Well, sure you do.
All of these neighbors, as we're calling them, create an effect similar to rhyme – they're similar sounds that work to unify the poem without distracting the reader from what the poem is saying. Good work, Bishop.