From Iowa to the mouth of the Mississippi River, towboat pilots pulled up to the riverbank, tied up their boats and walked off the job after their new union called a strike. "We think there's over 70 so far," said Coast Guard Lt. Matthew McGlynn. The board of Pilots Agree, which represents about a third of the nation's 3,000 river pilots and captains, voted to strike after 98 companies refused to negotiate. The union wants pay increases and improved working conditions. Many pilots kept working over the weekend, and industry officials said the strike had little effect. Broad, flat-bottomed barges are used to haul a variety of products.