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Bockstoce and Botkin Historical Sea Ice Data

Bockstoce and Botkin Historical Sea Ice Data

Whaling in the Bering Strait
Whaling in the Bering Strait. Lithograph by Benjamin Russell

Description of data

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More than three decades ago the International Whaling Commission’s Scientific Committee recommended a moratorium on the Eskimo harvest of bowhead whales (Balaena mysticetus) in the Bering, Chukchi, and Beaufort seas (B-C-B) because of a high (and then increasing) strike rate, combined with imprecise estimates that the bowhead population was low. As a result of this controversy Bockstoce and Botkin (1983) examined all existing logbook and journal records of the historical commercial whaling industry to estimate both the size of the bowhead population that existed at the beginning of the commercial harvest and the size of the harvest over time.

Among much other information the authors extracted and digitized daily data on the presence or absence of sea ice from logbook records of annual cruises to the B-C-B in an unbroken record from 1849 to 1914. These data that are presented below cover the years from 1850 to 1910. No ice reports were made in 1849, and there were very few cruises (hence inadequate data) from 1911 to 1914.

Download Ice and Open Sea Observed Spreadsheet (5.3 MB)
For explanation of data columns, see Key to data below

The data are meant as a companion to the paper:

  • Mahoney, A. R., J.R. Bockstoce, D.B. Botkin, H. Eicken and R.A. Nisbet, (2011), Sea ice distribution in the Bering and Chukchi seas: information from historical whaleships' logbooks and journals, Arctic,64(4), 465-477

The data include more than 52,000 daily observations in an unbroken 65 year record from 516 cruises. These represent 19% of the total 2,712 cruises.

Bockstoce and Botkin have also analyzed these data for information of bowhead whales and other marine mammals, and several of these publications are available at

John Bockstoce is an advisory curator at the New Bedford Whaling Museum in Massachusetts. He is an historian of the whaling industry and the fur trade in the Western Arctic.

Daniel B. Botkin is adjunct professor, Dept. of Biology, University of Miami, Coral Gables, FL, and Professor (Emeritus), Dept. of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA. He is an ecologist whose research has included the study of ecological effects of climate change, population dynamics of endangered species, field measurements of forest carbon storage, and theoretical ecological models. More information about his work can be found at and

Key to the Data

(Additional information about the data can be found in the key that appears with the Excel spreadsheet of all the data.)

SHIP_ID The identifing number of each of the 516 ships is listed here numerically, so that analyses can be done on a ship by ship basis.

MOVE_TYPE Most of the cruises were done by sail-powered ships, but after 1880 steamships also joined the whaling fleet. 0 indicates a sail-powered vessel. 1 indicates an auxiliary-powered vessel.

YEAR_MONTH_DAY_ Listed in standard format.

LAT_DEC decimal latitude.

LONG_DEC decimal longitude.

E-W East or west of the Prime (0) Meridian.

ICE COVER 0 no sea ice observed; 1 the presence of sea ice was recorded in the logbook or journal.

NaN means “Not-a-Number” and is a standard numerical notation used to indicate values that are non-finite or should be ignored.