Dave Bonta's three-line poem sketches a whole day in a few words. The speaker spends the afternoon working, and then, once evening comes, heads toward the sea. The title is the key. "Catadromous" describes fish, like freshwater eels, that live in rivers and travel down to the ocean to spawn. So the speaker is quietly compared to one of those fish, pulled by an instinct that work and daylight can't satisfy.
The last line, "a raw bed," is the strangest and most interesting part. A bed suggests rest, but "raw" makes it feel rough, exposed, even a little painful. The sea becomes a place to lie down, but not a comfortable one. The speaker seems tired and drawn to something elemental, though the poem doesn't say exactly what they feel. The mood is spare, restless and a bit solitary, with a sense of release mixed with rawness. The short lines and the dash leave a pause, as if the speaker is already looking out at the water.