The Charts Digitizing the Charts GIS Data Townsend References
Townsend Whaling Charts
The Wildlife Conservation Society has digitally captured the Townsend Whaling Charts that were published as a series of 4 charts with the article titled "The distribution of certain whales as shown by logbook records of American whale ships" by Charles Haskins Townsend in the journal Zoologica in 1935.
The 4 charts show the locations of over 50,000 captures of 4 whale species; sperm whales (36,908), right whales (8,415), humpback whales (2,883) and bowhead whales(5,114). Capture locations were transcribed from North American (“Yankee”) pelagic whale vessel log books dating from 1761 to 1920 and plotted onto nautical charts in a Mercator projection by a cartographer. Each point plotted on the charts represents the location of a whaling ship on a day when one or more whales were taken and is symbolized by month of the year using a combination of color and open and closed circles.
Townsend and his cartographer plotted vessel locations as accurately as possible according to log book records. When plotting locations on an earlier sperm whale chart published in 1931 the cartographer spaced points where locations were very dense, “extending areas slightly” for a number of whaling grounds. However for charts in preparation at this time Townsend states that “this difficulty is avoided by omitting some of the data, rather than extend the ground beyond actual whaling limits”. We assume that this statement refers to the 1935 charts but there is still some question as to whether the cartographer did in fact space locations and thus expand whaling grounds. A comparison of log book records with the charts is currently underway to assess the cartographic accuracy of chart locations and the possibility of spacing in dense areas. This study is being led by Dr. Tim Smith at Northeast Fisheries Science Center, Woods Hole, Massachusetts.
Chart A: Distribution of the sperm whale April - September
Chart B: Distribution of the sperm whale, October - March
Chart C: Distribution of northern and southern right whales
Chart D: Distribution of bowhead and humpback whales
Digitizing the Charts
Each of the 4 charts was scanned on a large format scanner at a resolution of 200dpi. The charts were then georeferenced in the native projection of the charts, the Mercator projection, using GIS software (ESRI ArcView 3.2). Each vessel capture location plotted on the charts was then digitized as a point feature and attributed with the month of capture. One GIS file (ESRI shapefile) was then created for each whale species represented by the charts; sperm whale, right whale, humpback whale and bowhead whale.
Digitizing errors include missed points, particularly from areas of dense chart locations, and incorrect assignment of month of capture because of difficulty distinguishing between chart colors. However to limit these errors multiple checks of digitized and chart locations were made and color enhancements of chart scans were used to ensure correct month assignments. Overall we are confident that at least 95% of catch locations have been digitized and that at least 95% of month attributes are correct.
For full resolution digital copies of the Townsend charts please contact Gillian Woolmer (email@example.com) or Dr. Eric W. Sanderson (firstname.lastname@example.org).
GIS Data for Download
Download ESRI shapefiles in geographic coordintes that contain the capture locations depicted by the charts.
Charles Haskins Townsend
Charles Haskins Townsend (1859–1944) was appointed the Director of the New York Aquarium in 1902 when management of the Aquarium was taken over by the Wildlife Conservation Society, then the New York Zoological Society. Townsend remained the Aquarium Director until 1937. For further information about Townsend and his works please contact Steve Johnson, Manager of the Bronx Zoo Library (email@example.com).
Townsend, C.H. 1935. The distribution of certain whales as shown by logbook records of American whaleships. Zoologica 19, No. 1:1-50, 4 charts.New Link
Townsend, C.H. 1931. Where the nineteenth century whaler made his catch. Zoologica 34, No. 6:173-179.
Reeves, R., Smith, T.D. Josephson, E.A., Clapham, P.J. and Woolmer, G. 2004. Historical observations of humpback and blue whales in the North Atlantic Ocean: Clues to migratory routes and possibly additional feeding grounds. Marine Mammal Science. Vol. 20 (4), pg 774-786.
Reviewed: 24 November 2006
Last Edited: 5 November 2004