(AP Photo/Felix Marquez)

They look like oversized rocks bleached by the sun. But focus a little more and you'll see the telltale flip of a fin, a beady eye, a gaping mouth. These are the 250 stingray carcasses littering the Chachalacas beach near the town of Ursulo Galvan on Mexico's Gulf Coast.

Residents first spotted them on Tuesday. Witnesses reported seeing fishermen dumping nets full of the bottom-dwelling creatures on the sandy shore. And while authorities are investigating, locals say they suspect anglers were trying to sell the stingrays to food venders and unloaded them when they didn't get a good deal.

(AP Photo/Felix Marquez)

Not familiar with the delicacy? According the the Associated Press, chopped stingray wings are commonly served as snacks in area restaurants. But the dish can go much farther than nibbles. If they are big enough, stingrays, which apparently taste like scallops, can be sautéed, fried, or grilled like any other filet and are found on menus all over the world.

But the stingray's popularity on the dinner table is worrisome for some wildlife activists. Because stingrays are related to sharks, which are increasingly farmed for their fins in Asia, a movement to protect them and their cartilaginous brethren has gained traction worldwide. Mexico actually joined an international fishing ban in 2011. "Mexico wishes to share with the international community our intention to declare [2012] a moratorium on shark and stingray fishing," said one of Mexico's United Nations representatives at the time.

Whether that ban went into effect in Mexico's territorial seas is not clear. But if the stingray slaughter on the beach this week is any indication, the creatures are a still a hunted commodity.