SC/59/AWMP1 1 Age Classification of Bowhead Whales using Recursive Partitioning

• Main Authors: J. G. Morita, J. C. George
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Subjects: Balaena mysticetus
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.505.58; http://www.iwcoffice.co.uk/_documents/sci_com/SC59docs/sc-59-awmp1.pdf

An algorithm was derived for using morphometric data to classify bowhead whales, Balaena mysticetus, into three age brackets: over 90 years (“very old”), 60-90 years (“old”), and under 60 (“younger”). Recursive partitioning was applied to a subset of the data set from postmortem examinations. This subset consists of whales with higher quality data scores and those with characteristics of “older ” animals such as near-maximum body length and baleen length, heavy scarring, ancient weapons imbedded in them, etc. Statistical analysis suggested that for males, body length and peduncle girth provide the most useful information for this age classification. For females, anterior flipper length and body length were the key variables for classifying age. If anterior flipper length is not available for females, then body length, baleen length and peduncle girth may be used to classify age.