Abstract
Currently, there is no standardised method for classifying skin lesions on small cetaceans from image data taken during boat-based surveys. As there is no way to be certain of aetiology from an image alone, these systems must be primarily based on descriptive gross morphology. Many classification systems used in the literature are subjective and only encompass lesions that have been seen in their population. Hence, no studies use the same system making it difficult to compare lesion occurrence among populations. This study presents a standardised classification system for use on boat-based photographic survey data. A comprehensive literature review was undertaken to develop the classification system encompassing the previous classification of skin lesions in dolphins; known aetiologies; and morphology of the skin during infection, injury and healing. Images from bottlenose populations in the Swan-Canning Estuary, Mandurah and Bunbury were also examined. The classification system developed separates lesions into two main types: possibly infectious and obvious injuries. Possibly infectious lesion categories include Hyperpigmented, Hypopigmented, Targetoid, Raised and/or Proliferative, Depressed/Sunken, Concentric Rings, Tattoolike and Discolouration. Injury categories include Bite Wounds, Abrasions/Excoriations and Anthropogenic. This system reduces the subjectivity and unnecessary splitting of categories that occurs when using existing classification schemes and will make studies that employ it more comparable. This is important as lesion occurrence can reflect population and ecosystem health. The system has been tested on the Swan-Canning Estuary population using 4547 images taken during boat-based surveys from 26/7/2011 to 30/6/2013.