A special Vermilion bay shrimp season will start Friday.The special season will be west of of the Atchafalaya River because the Department of Wildlife and Fisheries says recent biological samples show marketable size white shrimp are in there.  Time is of the essencse as high river stages predicted may lead to movements of the shrimp away from those waters into offshore waters before the opening of spring inshore shrimp season.   The specific area that is set to open Friday: state inside waters from the Atchafalaya River Ship Channel at Eugene Island delineated by the Channel red buoy line, westward to the western shore of Vermilion Bay and Southwest Pass at Marsh Island.