Distribution, ecology, and status of the white shark, Carcharodon carcharias, in the Mediterranean Sea

Boldrocchi, Ginevra; Kiszka, Jérémy J.; Purkis, Samuel J.; Storai, Tiziano; Zinzula, Luca; Burkholder, Derek A.

doi:10.1007/s11160-017-9470-5

Cited by 26 publications

(29 citation statements)

References 67 publications

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“…Similarly, we confirmed previous evidence of the prevalence of Mediterranean white sharks in western sectors (Boldrocchi et al, ), characterized by distinct bioecological and physical oceanographic characteristics from the Eastern Mediterranean. The west–east temperature (Bosc, Bricaud, & Antoine, ) and productivity (Coll et al, ) gradients would make the warmer Eastern Mediterranean waters a suboptimal habitat for adult endothermic white sharks (Carey et al, ).…”

Section: Discussionsupporting

confidence: 92%

“…Similarly, we confirmed previous evidence of the prevalence of Mediterranean white sharks in western sectors (Boldrocchi et al, 2017), characterized by distinct bioecological and physical oceanographic characteristics from the Eastern Mediterranean.…”

Section: Discussionsupporting

confidence: 91%

“…Conversely, they are in line with regions where the white shark occurrence data are sparse and infrequent, such as the Northwest Pacific Ocean (Christiansen et al, ). These results confirmed earlier evidence of regional declines provided by McPherson and Myers (), Boldrocchi et al, () and Ferretti et al () for a larger taxonomic group, but scaled‐down recent Red List assessments carried out by the IUCN, which classified the white shark as critically endangered in the Mediterranean Sea and European waters (Dulvy et al, ; Nieto et al, ). Our results suggest instead an overall decline of 61.5% over the last 10 years or three generations, which would classify the species as endangered (EN) “if the reduction causes may not have ceased or well understood,” as stated in IUCN Criteria Version 3.1 (A2‐bc).…”

Section: Discussionsupporting

confidence: 88%

“…By contrast, the colder and productive western sectors could represent resource hot spots for the species. These are in fact important breeding and feeding ground for bluefin tunas (Cermeño et al, ) and small cetaceans (Gnone et al, ; Lauriano, Pierantonio, Donovan, & Panigada, ), which are important food items for the white sharks (Figure d, Boldrocchi et al, ). This result highlights the critical importance of the western sectors for the persistence of white shark populations.…”

Section: Discussionmentioning

confidence: 99%

“…For example, several catches of young‐of‐the‐year white sharks reported for the Sicilian Channel suggested the presence of a nursery area in this sector (Fergusson, , ). The reduction in white shark sightings through the years from areas with a parallel strong decline of tuna populations, combined with recent and historical sightings in and around farm pens and tuna traps (Galaz & De Maddalena, ; Storai et al, ), suggested a close relationship between Atlantic Bluefin tuna ( Thunnus thynnus, Scombridae) and white shark occurrence in the Mediterranean Sea (Boldrocchi et al, ; De Maddalena & Heim, ; Kabasakal, ). Yet, more research is needed to understand population structure, size, movements and distribution within the area and their relations with environmental and biological variables.…”

Section: Introductionmentioning

confidence: 99%

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Abundance and distribution of the white shark in the Mediterranean Sea

et al. 2019

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Conservation of apex predators is a key challenge both in marine and terrestrial ecosystems. The white shark is a rare but persistent inhabitant of the Mediterranean Sea and it is currently assessed as “critically endangered” in the region. However, the population trends and dynamics of this species in the area are still unknown. Little is known about white shark distribution, habitat use and population abundance trends, aspects that are critical for conservation and management. In this study, we built the most comprehensive database of white shark occurrence records in the region. We collected 773 different records from different sources and used them to characterize the spatial and temporal patterns of abundance of Mediterranean white sharks between 1860 and 2016. We analysed these data by using generalized additive models and used spatially disaggregated information on human population abundance as a proxy of observation effort. Our results suggest a complex trajectory of population change characterized by a historical increase and a more recent reduction (61%, range 58%–72%) since the second half of the 20th century. In particular, analyses reveal a 52% (range 37%–88%) to 96% (range 92%–100%) overall decline in different Mediterranean sectors and a contraction in spatial distribution. Here, we provide the first reconstruction of abundance trends and offer new hypotheses regarding the drivers of change of white sharks in the Mediterranean. Our approach can be broadly applied to data‐poor contexts to reconstruct change and inform the conservation of endangered top predators in the Mediterranean Sea and other intensely used marine regions.

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Section: Discussionsupporting

confidence: 92%

Section: Discussionsupporting

confidence: 91%

Section: Discussionsupporting

confidence: 88%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Abundance and distribution of the white shark in the Mediterranean Sea

et al. 2019

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Data‐mining social media platforms highlights conservation action for the Mediterranean Critically Endangered blue shark Prionace glauca

Boldrocchi

Storai²

2021

Aquatic Conservation

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1. The Mediterranean Sea represents an area of elevated risk of extinction for sharks, where data deficiency is a pervasive problem. 2. To compensate for such a paucity of information, this study investigated the use of social media content as a complementary approach to evaluate the distribution and habitat use of the Critically Endangered blue shark Prionace glauca in coastal waters, as well as public perceptions of the sharks. 3. Through social media data mining a total of 146 records, comprising 158 individual blue sharks approaching Italian coastal waters, have been recorded from 2011 to 2020.4. This study revealed that, over the past decade, blue sharks regularly visited Italian coastal habitats for extended periods of time. Differences in the temporal distribution of blue sharks by sex and size appear to be linked to reproductive activity. The higher number of adult females approaching the shore in spring and the increase in young-of-the-year (YOY) sightings in the following months possibly indicate parturition in coastal waters. Spatial analyses also showed that certain Italian coastal areas, such as those in Calabria and Puglia, were preferred coastal habitats for this species. 5. Results also indicate that social media platforms can be considered an evergrowing source of data on wildlife, which can shed light on the occurrence and distribution of endangered shark species in poorly known habitats. Furthermore, social media platforms should be used for awareness campaigns to educate the public, as this study showed that negative reactions to shark encounters remain widespread.

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Estimating the spatial distribution of the white shark in the Mediterranean Sea via an integrated species distribution model accounting for physical barriers

Panunzi,

Moro,

Marques

et al. 2024

Environmetrics

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Conserving oceanic apex predators, such as sharks, is of utmost importance. However, scant abundance and distribution data often challenge understanding the population status of many threatened species. Occurrence records are often scarce and opportunistic, and fieldwork aimed to retrieve additional data is expensive and prone to failure. Integrating various data sources becomes crucial to developing species distribution models for informed sampling and conservation purposes. The white shark, for example, is a rare but persistent inhabitant of the Mediterranean Sea. Here, it is considered Critically Endangered by the IUCN, while population abundance, distribution patterns, and habitat use are still poorly known. This study uses available occurrence records from 1985 to 2021 from diverse sources to construct a spatial log‐Gaussian Cox process, with data‐source specific detection functions and thinning, and accounting for physical barriers. This model estimates white shark presence intensity alongside uncertainty through a Bayesian approach with Integrated Nested Laplace Approximation (INLA) and the inlabru R package. For the first time, we projected species occurrence hot spots and landscapes of relative abundance (continuous measure of animal density in space) throughout the Mediterranean Sea. This approach can be used with other rare species for which presence‐only data from different sources are available.

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Distribution, ecology, and status of the white shark, Carcharodon carcharias, in the Mediterranean Sea

Cited by 26 publications

References 67 publications

Abundance and distribution of the white shark in the Mediterranean Sea

Abundance and distribution of the white shark in the Mediterranean Sea

Data‐mining social media platforms highlights conservation action for the Mediterranean Critically Endangered blue shark Prionace glauca

Estimating the spatial distribution of the white shark in the Mediterranean Sea via an integrated species distribution model accounting for physical barriers

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