Was it returned to the sea (alive) or did your friend eat it?
I once made the mistake of tasting skate (a closely related species - both elasmobranchs). Boy, were the urea levels high in it. I wouldn't have been surprised if I'd been eating AMMONIA as well.
One mouthful and that was it for me. The bin had the rest.
Great picture, though. :)
RE: Sand Shark