No more seriously, I did wonder and found this...
'In Celtic tradition there were two aspects of the deer: the feminine element, called Eilid in Gaelic, the female red deer, symbolizing femininity, gentles and grace. It was believed that the deer called to men from the kingdom of the fairies to free them from the trappings of the earthly world and taking them to the world of magic. Deer often turned into women in such legends in order to avoid being hunted. '
Which would be a bit weird with the whole mermaid symbolism. Or do woman trap men but that's how they free them too?
... I should probably shut up now.