eldorfdragonsbane

Been actually playing Fallout 4 instead hanging around the Sanctuary Hills area, been noticing along the coast all the corpses of the dolphins (sharks?), making me think that these dolphins (and the speargun) are hints about one of the upcoming DLC's. I know I have read online also about someone following one of the underwater pipes and supposedly finding a spear/harpoon gun, if this is true and it is/will be usable underwater then having the mutant dolphins as an enemy when you are in the water (hopefully they stick to the coast not the rivers and lakes/ponds) would work