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

Abstract

1. 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.2. 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.3. 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. 4. 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.

Eavesdropping on dolphins: Investigating the habits of bottlenose dolphins (Tursiops truncatus) through fixed acoustic stations

“…Nevertheless, further analysis considering boat traffic, both in terms of numerousness and noise level produced, are necessary to confirm the effect of anthropogenic disturbance on the residency of bottlenose dolphins in the waters of the Marine Protected Area of Portofino. Additionally to noise disturbance, marine traffic has negative effects on the survival of cetaceans, various species have been recorded dead or alive with evidence of propeller wounds in the Pelagos Sanctuary [62, 63]. In conclusion, this work confirms the importance of the study area for bottlenose dolphin conservation in the Mediterranean, as underlined in previous studies [15].…”

Towards more compassionate wildlife research through the 3Rs principles: moving from invasive to non-invasive methods

“…Indo-Pacific bottlenose dolphins Tursiops aduncus (Gomez-Salazar et al 2011, Bichell et al 2018, sperm whales Physeter macrocephalus (Alessi et al 2014), Asian black bears Ursus thibetanus (Higashide et al 2012), polar bears Ursus maritimus (Anderson et al 2007), Australian sea lions Neophoca cinerea (Osterrieder et al 2015), cougars Puma concolor (Alexander and Gese 2018), tigers Panthera tigris (Karanth et al 2006), cheetahs Acinonyx jubatus (Kelly 2001), giant pandas Ailuropoda melanoleuca (Zheng et al 2016), salamanders, Eurycea tonkawae, Ambystoma opacum and Salamandrina perspicillata (Gamble et al 2008, Bendik et al 2013, Romiti et al 2017, crustaceans Rhynchocinetes typus and Chionoecetes opilio (Gallardo-Escarate et al 2007, Gosselin et al 2007, manatees Trichechus manatus latirostris (Langtimm et al 2004), Majorcan midwife toads Alytes muletensis (Pinya and Perez-Mellado 2009), common European vipers Vipera berus (Bauwens et al 2018), green sea turtles Chelonia mydas (Gatto et al 2018), wunderpus octopuses Wunderpus photogenicus (Huffard et al 2008), little brown bats Myotis lucifugus (Amelon et al 2017), jewelled geckos Naultinus gemmeus (Knox et al 2013), newts Ichthyosaura alpestris and Lissotriton vulgaris (Mettouris et al 2016), and even beetles Lucanus cervus, Rosalia alpina and Rhynchophorus ferrugineus (Caci et al 2013, Romiti et al 2017, Diaz-Calafat et al 2018.…”

Photo-id of blue whale by means of the dorsal fin using clustering algorithms and color local complexity estimation for mobile devices

“…These repositories can be examined manually and visually to develop a single set of classes and sub-classes; however, as the number of images in the collection of the repository increases beyond a person's ability to process visual characteristics of the candidate to see whether or not coincide with a new photograph by hand-eye, the development of techniques more fast and automated to compare the new photographs obtained above is required [5]. The widely use photo-id technique to identify wild species individuals employs natural markings such as pigmentation patterns, the spot patterns in the fur of cheetahs [6] or morphology and distribution of these spots in the red pandas [7], the fin shape of the cetaceans or nick and notches in the dolphin's fin [5,8], or other features such as scars also they can be identified [9]. This non-invasive technique uses images acquired from a determinate distance to obtain the natural markings to be identified and classified with the least disturbance possible [9].…”

“…The widely use photo-id technique to identify wild species individuals employs natural markings such as pigmentation patterns, the spot patterns in the fur of cheetahs [6] or morphology and distribution of these spots in the red pandas [7], the fin shape of the cetaceans or nick and notches in the dolphin's fin [5,8], or other features such as scars also they can be identified [9]. This non-invasive technique uses images acquired from a determinate distance to obtain the natural markings to be identified and classified with the least disturbance possible [9]. The photo-id technique has long been used to identify large whales and was first used by researchers in the 1970s, by recognizing the pigmentation patterns of the ventral side of the caudal fin in humpback whales [10].…”

“…The system performs the comparison of new images taken in the field to identify brands and caudal fins of the whale. From this, implementation has been speeding up the photo-id of some marine animals [5,[8][9][10]. The search of natural patterns by visual comparison of hundreds of images to find an individual identity is susceptible to errors [8,11].…”