A question about shark fin soup...?

I have read that sharks are being slaughtered by the millions every year and that the numbers of certain species are rapidly being depleted by fishermen who are providing shark fins to the mostly Chinese restaurants, but also to Singaporean and Taiwanese restaurants as well. What is puzzling is that the shark fins apparently have no nutritional value and contain very high levels of methyl mercury. My question is, why do people eat it, especially women who have fetuses developing in their wombs for which the mercury will have serious neurological effects on? I suppose they don't warn people about the consequences of eating shark fin soup in China. Am I right?