The ecology of the whale shark in Djibouti

Boldrocchi, Ginevra; Omar, Moussa; Azzola, Annalisa; Bettinetti, Roberta

doi:10.1007/s10452-020-09758-w

Cited by 22 publications

(16 citation statements)

References 59 publications

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“…Our study provides some of the first information on the movement patterns of whale sharks in the eastern part of the northern Arabian Sea. Subpopulations of whale sharks in the southern and central-western Indian Ocean have been suggested to be separated from the northwestern Indian Ocean and Arabian Sea region based on photo identification and isotopic studies (Prebble et al, 2018;Boldrocchi et al, 2020). Additionally, Sequeira et al (2013) hypothesized that whale sharks could potentially travel between Gujarat and the Maldives, indicating the connectivity between a subpopulation.…”

Section: Discussionmentioning

confidence: 99%

“…The migratory behavior of whale sharks, in combination with their slow growth rates (Meekan et al, 2020) and K-selected life history, make populations highly vulnerable to anthropogenic pressures, such as ship strikes (Speed et al, 2008;Lester et al, 2020), bycatch and targeted fishing (Capietto et al, 2014) and pollution (Boldrocchi et al, 2020). These threats are of particular concern as the species is classified as "Endangered" on the IUCN Red List (Pearce and Norman, 2016).…”

Section: Introductionmentioning

confidence: 99%

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First Insights Into the Horizontal Movements of Whale Sharks (Rhincodon typus) in the Northern Arabian Sea

Arrowsmith

Paidi²,

Bloch³

et al. 2021

Front. Mar. Sci.

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Whale sharks off the western coast of India have suffered high levels of fishing pressure in the past, and today continue to be caught in small-scale fisheries as by-catch. Additionally, coastlines in this region host very large and growing human populations that are undergoing rapid development. This exacerbates ongoing anthropogenic threats to this species such as pollution, habitat loss, and ship traffic. For these reasons, there is an urgent need for data on movement patterns of whale sharks in this region of the Indian Ocean. Here, we address this issue by providing the first data on the horizontal movements of whale sharks tagged in the northern Arabian Sea off the western coast of the Indian state of Gujarat. From 2011 to 2017, eight individuals, ranging from 5.4 to 8 m were tagged and monitored using satellite telemetry. Tag retention varied from 1 to 137 days, with the sharks traveling distances of 34 – ∼2,230 km. Six of the eight individuals remained close to their tagging locations, although two sharks displayed wide ranging movements into the Arabian Sea, following frontal zones between water masses of different sea surface temperatures. We explore the relationship between the movement patterns of these whale sharks and the physical and biological processes of the region.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

First Insights Into the Horizontal Movements of Whale Sharks (Rhincodon typus) in the Northern Arabian Sea

Arrowsmith

Paidi²,

Bloch³

et al. 2021

Front. Mar. Sci.

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“…Considering the general lack of knowledge on this species, and that is listed as Endangered on the IUCN Red List, with a decreasing population [2,3], a comprehensive research study on the whale shark population has been carried out in the Gulf of Tadjoura (Djibouti) since 2016. Research findings showed that the Djibouti whale shark population comprises more than 190 individuals, which show site fidelity to this area by returning each year [4]. Whale sharks use Djibouti as a seasonal feeding ground in October-February, due to the increase in prey availability driven by the southwest monsoon that enhances the upwelling of nutrient rich waters [4].…”

mentioning

confidence: 99%

“…Research findings showed that the Djibouti whale shark population comprises more than 190 individuals, which show site fidelity to this area by returning each year [4]. Whale sharks use Djibouti as a seasonal feeding ground in October-February, due to the increase in prey availability driven by the southwest monsoon that enhances the upwelling of nutrient rich waters [4]. The arrival of northeast monsoon winds prevents the upwelling phenomenon, causing the disappearance of whale sharks [4].…”

mentioning

confidence: 99%

“…Whale sharks use Djibouti as a seasonal feeding ground in October-February, due to the increase in prey availability driven by the southwest monsoon that enhances the upwelling of nutrient rich waters [4]. The arrival of northeast monsoon winds prevents the upwelling phenomenon, causing the disappearance of whale sharks [4]. The apparent absence of whale sharks has led to the hypothesis that sharks migrate to other locations.…”

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confidence: 99%

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Whale Shark Conservation Hindered by Lack of Habitat Protection

Bettinetti

2020

IJESNR

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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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The ecology of the whale shark in Djibouti

Cited by 22 publications

References 59 publications

First Insights Into the Horizontal Movements of Whale Sharks (Rhincodon typus) in the Northern Arabian Sea

First Insights Into the Horizontal Movements of Whale Sharks (Rhincodon typus) in the Northern Arabian Sea

Whale Shark Conservation Hindered by Lack of Habitat Protection

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

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