Mmmrrrggglll is the chieftain of the Grimscale Murlocs who are situated at both the Tranquil Shore and the Golden Strand. It is possible that he was the one responsible for the theft of cargo from Captain Kelisendra's ship. To find him, simply keep an eye throughout the Golden Strand as he wanders the length of the Murloc camps on the shoreline. He can easily be recognized by his somewhat unique colors.