Putative historical occurrence of North Atlantic right whales in mid-latitude offshore waters: 'Maury's Smear' is likely apocryphal

The seasonal distribution of North Atlantic right whales Eubalaena glacialis is generally well known in coastal areas but poorly known in offshore portions of the species' range. Two main areas of offshore occurrence have been known or suspected, based largely on evidence from 19th century American whaling logbooks: the Cape Farewell Ground east and south-east of the southern tip of Greenland, and 'Maury's Smear', a mid-latitude area bounded by 35 to 43degreesN and 25 to 48degreesW. While the modern occurrence of whales on the old Cape Farewell Ground has been demonstrated by recent sightings, this is not the case for Maury's Smear. Moreover, by examination of original sources we provide direct evidence that the offshore distribution illustrated by Maury in 1852 and 1853 was at least partly and possibly entirely erroneous, based on faulty data extraction and transcription procedures. Our results cast doubt on Maury's charts of 19th century whale distribution more generally, leading us specifically to question the reliability of his depictions of right whale occurrence in offshore portions of other ocean basins.