Towards a Classification Scheme for External Injuries of Marine Mammals

Marine mammals are increasingly exposed to human activities. They are also subjected to natural threats, including inter- and intraspecific interactions. Quantitative data about the impacts of these potential threats on populations are scarce. A widely used method to identify potential threats to the survival of populations is the classification and quantification of injuries resulting from anthropogenic and natural interactions. Studies which have quantified the prevalence of injuries in marine mammal populations have used different criteria for classifying injury types and different methods of reporting injuries. However, the cause of injuries is often speculative and therefore unsuitable as the primary basis for a classification system. The lack of a universal method for reporting the prevalence of injuries in marine mammals hampers comparative studies of geographic, temporal, and inter- and intraspecific variation in the prevalence of injuries. We propose a classification system for quantifying external injury types in marine mammals which defines injury types on the basis of their external morphology. We review current knowledge about the cause(s) of these injury types and identify topics for further study. Standardized reporting of injuries will hopefully provide a better insight into the factors that affect the health and survival of marine mammal populations worldwide.