Daily locations of whaling vessels extracted from a sample of American whaling logbooks for voyages departing between 1780 and 1920. Days with no whale observations and days with observations of sperm, right, bowhead, humpback, and gray whales and locations of key ports were distinguished by the colors indicated. The time periods were selected to best reflect the similarities in distribution patterns within time periods.
Source: Smith TD, Reeves RR, Josephson EA, Lund JN (2012) Spatial and Seasonal Distribution of American Whaling and Whales in the Age of Sail. PLoS ONE 7(4): e34905. doi:10.1371/journal.pone.0034905