NEW YORK (MarketWatch) -- The U.S. Coast Guard said the slick from the BP Plc BP, -1.18% oil spill in the Gulf of Mexico is nearing the Loop Current, a stream of ocean water that moves around the south side of Florida and into the Atlantic Ocean. "Satellite imagery indicates that the main bulk of the oil is dozens of miles away from the Loop Current, but that a tendril of light oil has been transported within close proximity," the Coast Guard said in its update late Tuesday. "NOAA is conducting ongoing aerial observations to determine with certainty whether or not the oil has actually entered the Loop Current, and continues engage experts within and outside government to develop long-term oil movement forecasts." The area now close to fishing represents 45,728 square miles, which is slightly less than 19% of Gulf of Mexico federal waters.