if you guys ever go to ensenada for fish tacos, politely ask the lady behind the grill what is the meat in the taco your munching on, there is a good chance she'll tell you shark, if not its either she is lying or she just happened to get cheap fish. it all boils down to economics, shark meat is cheap compared to other fish and if processed properly it is firm, white and quite tasty, so to make a few bucks they comonly use them little swiming sandpaper blocks. I've personally done ceviche and fish tacos out of shovelnose, pinbacks leopards.... all with good results.

one downside though, they are a pain to clean.
to clean them:
chop the head off, then the tail and fins (could save them for soup but its a whole different ballgame there) to skin them with a paring knife peel enough of the tail skin so you have a good firm grip, once you do yanke it with even pressure till youre done. once naked slice the meat in half twice, along both sides of the spine and remove it. rinse it thoroughly and youre done.
I might have ommited a few things since its been a good while since I've done this but in a nutshell thats the story.

good luck, again bleeding, cleaning and icing the meat as fast asa possible is imperative to get good results.