For two days, it drifted through the waters off Gwadar, carried by currents whose secrets remain unknown. On Wednesday, the sea surrendered its silent passenger to the shore: a 30-foot blue whale, one of the ocean's most magnificent creatures, found dead near Gwadar East Bay. Its lifeless arrival has once again cast a shadow over Pakistan's fragile marine ecosystem, raising troubling questions about the survival of some of the ocean's rarest inh…