Analysis of the natural markings of Risso’s dolphins (<i>Grampus griseus</i>) in the central Mediterranean Sea

Mariani, Monica; Miragliuolo, Angelo; Mussi, Barbara; Russo, Gìovanni Fulvio; Ardizzone, Giandomenico; Pace, Daniela Silvia

doi:10.1093/jmammal/gyw109

Cited by 20 publications

(21 citation statements)

References 33 publications

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“…Mixed groups of common dolphins with other cetacean species were recorded here in both social media and research datasets, reinforcing similar observations already reported in the Mediterranean (Arcangeli et al, 2017;Frantzis & Herzing, 2002;. This kind of association generally involved a few common dolphin individuals within a group of striped dolphins, supporting the hypothesis that the relative low abundance of common dolphin restrains the possibility of forming single-species groups (Arcangeli et al, 2017;Frantzis & Herzing, 2002 (Azzellino et al, 2008(Azzellino et al, , 2012Casacci & Gannier, 2000;David & Di-Meglio, 2012;Gannier, 2005;Mariani et al, 2016;Moulins, Rosso, Ballardini, & Würtz, 2008;Pace, Miragliuolo, & Mussi, 2012;Praca & Gannier, 2008). This kind of habitat was less represented in our study area, and results seem to be in accordance with previous studies in the central Tyrrhenian Sea (Arcangeli et al, 2017).…”

Section: Other Speciessupporting

confidence: 87%

“…Risso's dolphin was observed three times, and only one stranding occurred over the 10‐year period. On average, Risso's dolphin in the Mediterranean appears to be a low‐density species, showing a preference for deep waters over steep slopes and submarine canyons (Azzellino et al, , , ; Casacci & Gannier, ; David & Di‐Meglio, ; Gannier, ; Mariani et al, ; Moulins, Rosso, Ballardini, & Würtz, ; Pace, Miragliuolo, & Mussi, ; Praca & Gannier, ). This kind of habitat was less represented in our study area, and results seem to be in accordance with previous studies in the central Tyrrhenian Sea (Arcangeli et al, ).…”

Section: Discussionmentioning

confidence: 99%

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An integrated approach for cetacean knowledge and conservation in the central Mediterranean Sea using research and social media data sources

Pace

Giacomini

Campana

et al. 2019

Aquatic Conservation

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Sources of data other than those derived from conventional research protocols may contribute valuable information to fill gaps in knowledge about cetacean occurrences and diversity in a given area and help address conservation issues. The performance of a method to examine cetacean communities based on presence records systematically derived from shared photographs and videos posted by boaters and maritime operators on social media (e.g. YouTube and Facebook) combined with patchy distributed visual/acoustic data collected by researchers has been evaluated. Records (N = 1,274) gathered over a 10‐year period (2008–2017) have been used to obtain insights into species' presence and habitat selection in a scattered study area of the central Mediterranean Sea (Italy). The effectiveness of the method, practical and theoretical advantages, limitations, and challenges of using data originated from social media for research and conservation purposes are discussed. Seven out of the eight cetacean species regularly residing in the Mediterranean have been reported in the area, with different relative densities. Maximum entropy modelling techniques have been applied to the datasets derived from (a) social media, (b) research surveys, and (c) the combination of the two, using six fixed variables as proxies for cetacean presence. Distance from the coast and depth emerged as the main variables predicting encounters, with specificities related to the ecology of the species. The approach was reliable enough to obtain broad‐scale, baseline information on cetacean communities in the region, on the basis of which initial conservation recommendations and future research programmes can be proposed. With the increasing need for studying whale and dolphin population ecology coming from national/international directives, support from citizens to aid research may act as a practical, inexpensive solution to gathering extensive spatial–temporal data for regional‐scale monitoring and for the development of management priorities.

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Section: Other Speciessupporting

confidence: 87%

Section: Discussionmentioning

confidence: 99%

An integrated approach for cetacean knowledge and conservation in the central Mediterranean Sea using research and social media data sources

Pace

Giacomini

Campana

et al. 2019

Aquatic Conservation

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“…In this study, thirteen mark types were identified in Aeolian bottlenose dolphins exposed to a wide range of natural and anthropogenic conditions, especially fishing activities. All skin marks were classified according to previous descriptions [16, 19, 32, 36, 62, 68, 71]. Of all the skin mark types, only 30.8% showed a clear natural cause, while 69.2% were associated with traumata.…”

Section: Discussionmentioning

confidence: 99%

Skin marks in bottlenose dolphins (Tursiops truncatus) interacting with artisanal fishery in the central Mediterranean Sea

Leone¹,

Ferraro²,

Boitani

et al. 2019

PLoS ONE

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Skin marks occur frequently in many cetacean species across the globe revealing a broad spectrum of causes, including social interactions, infectious diseases and injuries produced by anthropogenic factors. The current study used photo-id data from 2005–2014 to estimate the skin mark pattern on resident bottlenose dolphins (Tursiops truncatus) from the Aeolian Archipelago (Italy). Thirteen skin mark types were identified and their origin, prevalence and permanence time were examined. The pattern of skin marks was assessed for the abundance, richness, distribution and severity in six body regions and compared among age classes, sex and degree of dolphins’ interaction with trammel nets (DIN). Our results showed higher prevalence, abundance, richness and distribution of skin marks in adults than in the younger age classes, with the exception of black marks and white ring lesions. The prevalence and abundance of skin marks were higher in males than females, with the exception of scratches and white patches. Moreover, gunshot wounds, mutilations and irregular dorsal fin edges were found only on adult males. Since males showed higher DIN than females and, in dolphins with higher DIN, skin marks were more abundant and frequently distributed in different body regions, the skin mark pattern in regard to DIN seems to be sex-related. The more severe marks were observed on adults, males and dolphins with higher DIN, namely skin disorder, tooth rake marks, small shallow indentations, deep indentations and mutilations. On the contrary, the severity of scratches, white patches and dark ring lesions was higher in females than males, but not significantly related to DIN and age of the individuals. Our results showed that photo-id data provide an efficient and cost-effective approach to document the occurrence of skin marks in free-ranging bottlenose dolphin populations, a critical step toward understanding the cause and supporting the conservation strategies.

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“…While pigmentation has been investigated over time using visual techniques for some poorly-marked delphinids 20 , 21 , no studies have statistically examined its temporal stability or discriminatory power for individual identification. In our study, neither visual nor statistical analyses found any evidence that the pigmentation patterns of adult common dolphins in the Hauraki Gulf changed over time.…”

Section: Discussionmentioning

confidence: 99%

“…The techniques and workflow presented here could be used to examine the viability of dorsal fin pigmentation as an identifying feature for other common dolphin populations. Moreover, a number of other delphinids exhibit pigmentation patterns, including Baiji ( Lipotes vexillifer ), Indo-Pacific humpback ( Sousa chinensis ), Irrawaddy ( Orcaella brevirostris ), pink river ( Inia geoffrensis ), tucuxi ( Sotalia fluviatilis ), Risso’s ( Grampus griseus ), and spotted ( Stenella frontalis ) dolphins 16 , 20 , 28 – 32 . Of these species, pigmentation prevalance is rarely investigated 29 , 32 .…”

Section: Discussionmentioning

confidence: 99%

Examining the viability of dorsal fin pigmentation for individual identification of poorly-marked delphinids

Pawley

Hupman

Stockin

et al. 2018

Sci Rep

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Dolphin photo-identification has traditionally relied only on distinctive markings on the dorsal fin—this is problematic for delphinids whose populations exhibit a low mark ratio. We used common dolphins (genus Delphinus) as a model species to assess the viability of using pigmentation for photo-identification. Using a photo-identification catalogue of 169 adult individuals collected between 2002 and 2013, we extracted features that quantified pigmentation in a manner that was robust to lighting artefacts and dorsal fin orientation. We determined the proportion of individuals which exhibited pigmentation and examined temporal stability by (i) visually examining individuals and (ii) testing for seriation. We found 88–91% of images could be manually matched to the correct individual in the catalogue based on pigmentation patterns alone. A linear discriminant analysis classifier correctly identified the correct individual 77% of the time. We found 95% common dolphins exhibited distinctive pigmentation—all of which were temporarily stable. Our work challenges the current thinking that pigmentation is an unreliable feature for delphinid photo-identification and suggests that this feature could be applied to common dolphins and other poorly-marked delphinids.

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Analysis of the natural markings of Risso’s dolphins (Grampus griseus) in the central Mediterranean Sea

Cited by 20 publications

References 33 publications

An integrated approach for cetacean knowledge and conservation in the central Mediterranean Sea using research and social media data sources

An integrated approach for cetacean knowledge and conservation in the central Mediterranean Sea using research and social media data sources

Skin marks in bottlenose dolphins (Tursiops truncatus) interacting with artisanal fishery in the central Mediterranean Sea

Examining the viability of dorsal fin pigmentation for individual identification of poorly-marked delphinids

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