Quantitative assessment of wound healing based on long-term follow up of tagged gray and blue whales

Despite extensive use of implant tags for more than 30 years in large whales, long-term consequences have generally only been examined on short-term, anecdotal basis or in generalized terms. We evaluated the physical condition of the tag site and healing characteristics in 35 gray whale tagging events from 2009 to 2013 and 83 blue whale tagging events that took place in the eastern North Pacific from 1993 to 2008. Over 900 photographs showing the tag site taken from the time of tagging through 2013 were scored on a set of objective criteria by two independent reviewers. In addition, five marine mammal veterinarians/pathologists familiar with large whales provided expert overall evaluation of the long-term risk to the animals health based on the overall time series for each individual. Swelling and depressions were the most common conditions noted at some point during tag follow up in 73% of gray and 27% of blue whales and depressions in 83% of gray and 64% of blue whales. An inter-rater agreement analysis (κ Statistic) demonstrated a strong agreement between the two reviewers scoring the presence or absence, and type of lesion associated with the tag. In general, swellings observed on tagged gray whales were more evenly distributed in the level of relative severity (mild, moderate, severe), whereas swellings tended to be more moderate in blue whales. Depressions were more moderate to severe in gray whales compared to mild to moderate in blue whales. Earlier external tags were associated with two cases of long term severe swellings in blue whales as a likely result of one of the attachment prongs remained embedded for many years. The veterinary panel’s subjective expert assessment showed a high degree of variation by reviewer but four or more reviewers concurred at least a possible health risk was indicated for half the gray whales but only 11% of blue whales. Species differences were likely influenced by the longer but sparser history on blue whales versus the more frequent but short-term follow up of gray whales and the progression of conditions post tagging. While evaluations of tag site conditions have been conducted before this represents the largest long term time series of multiple species conducted.


Norman, S, J Calambokidis, K Flynn, B  Mate, C Hayslip, F Gulland, M Moore, S  Raverty, D Rostein, A Zerbini, A Douglas, D Gendron, and R Sears. 2015. Quantitative assessment of wound healing based on long-term follow up of tagged gray and blue whales. Abstract (Proceedings) 21st Biennial Conference on the Biology of Marine Mammals, San Francisco, California, December 14-18, 2015.