Photo‐identification of sperm whales in the north‐western Mediterranean Sea: an assessment of natural markings

Abstract

ABSTRACT Photo‐identification is an important, non‐invasive tool that can be used to obtain data about cetacean population dynamics that are essential for proper environmental management. A standardized protocol is crucial for obtaining optimal results, particularly for long‐lived and highly migratory species such as sperm whales (Physeter macrocephalus) but also to study resident populations. Photo‐identification of individuals using natural marks has been widely used to study sperm whales in the Mediterranean Sea. However, the prevalence of the marks used for identification is unknown. Thus, the goal of this study was to identify which mark types are most useful for identifying individual sperm whales. A photo‐identification catalogue of sperm whales from the north‐western Mediterranean Sea was produced and examined to determine the most frequent mark types present on whales in the study area. Mark types and their distribution were described, prevalence and the size of each mark type were calculated, variability in visibility was investigated, and gain and loss rates were analysed. Analysis of natural pigmentation may characterize sperm whale flanks in this study area as the best and most convenient element on which matching technique can be based. Indeed, this technique led to the identification of 97% of photographed individuals. Copyright © 2014 John Wiley & Sons, Ltd.