Out here on the Chesapeake, they call it drudging for arsters, says Charles Kuralt in his book On the Road with Charles Kuralt. The Standard English verb dredge is pronounced with a centralized vowel by Chesapeake Bay oyster fishermen, yielding drudge. Drudge in turn has been picked up by city dwellers on the Delmarva Peninsula; a survey of some young people from Baltimore revealed that they did not even know that there was a Standard English verb dredge. Kuralt gives the regional pronunciation a whimsical folk etymology with the standard meaning of drudge, to do tedious or unpleasant work, observing, Whatever you do for a living, it's not as hard as drudging for arsters.