After observing the way the lights move when disturbed, Daryl will try and take a long, sturdy branch, and attempt to poke the lights, seeing if he can feel them against the branch. He'll wade in as far as he can without, yk, going under, and wait for the lights to return if his movement in the water disturbs them any. His current theory is bioluminescent marine life ("glowing fish") which might be (!!!) edible.

If step one of Long John Silver's Revenge goes to plan and he can feel a psychical object moving against the branch, he'll get started on making a spear with his branch and knives (should take ~3hrs?), and attempt some spearfishing using similar methods (get into the water, stay still, wait, aim, strike).