The Baltic Exchange's dry bulk sea freight index, tracking rates for ships carrying dry bulk commodities, snapped its four-day gaining streak on Thursday, as rates declined across all vessel segments.The overall index, which factors in rates for capesize, panamax and supramax shipping vessels, lost 15 points, or 0.9%, to 1,683.The capesize index fell 14 points, or 0.6%, to 2,459.