St. Helena: An Important Reproductive Habitat for Whale Sharks (Rhincodon typus) in the Central South Atlantic

Perry, Cameron; Clingham, Elizabeth; Webb, D. Harry; Parra, Rafael de la; Pierce, Simon J.; Beard, Annalea; Henry, Leeann; Taylor, Beth; Andrews, Kenickie; Hobbs, Rhys; Araújo, Gonzalo

doi:10.3389/fmars.2020.576343

Cited by 15 publications

(17 citation statements)

References 51 publications

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“…Norman et al, 2017b;Cochran et al, 2019), satellite telemetry (e.g. Perry et al, 2020), or biochemical approaches (e.g. Prebble et al, 2018), to get a better understanding of the habitat use and movement ecology of this species.…”

Section: Introductionmentioning

confidence: 99%

“…Whale sharks target high density patches of food (Rohner et al, 2015a;Boldrocchi et al, 2020) which, in a highly oligotrophic environment like the tropics, often means short-lived pulses spread over broad spatial scales. Previous studies using passive acoustic telemetry at Mafia Island, Tanzania (Rohner et al, 2020), Al Lith, Saudi Arabia (Cochran et al, 2019) and at St. Helena Island (Perry et al, 2020), produced estimates of residency based on tag detection at each site. It remains unclear if these metric can be reconciled with sightingsderived data from photo-ID.…”

Section: Introductionmentioning

confidence: 99%

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Improving sightings-derived residency estimation for whale shark aggregations: A novel metric applied to a global data set

Araújo

Agustines

Bach³

et al. 2022

Front. Mar. Sci.

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The world’s largest extant fish, the whale shark Rhincodon typus, is one of the most-studied species of sharks globally. The discovery of predictable aggregation sites where these animals gather seasonally or are sighted year-round – most of which are coastal and juvenile-dominated – has allowed for a rapid expansion of research on this species. The most common method for studying whale sharks at these sites is photographic identification (photo-ID). This technique allows for long-term individual-based data to be collected which can, in turn, be used to evaluate population structure, build population models, identify long-distance movements, and assess philopatry and other population dynamics. Lagged identification rate (LIR) models have fewer underlying assumptions than more traditional capture mark recapture approaches, making them more broadly applicable to marine taxa, especially far-ranging megafauna species like whale sharks. However, the increased flexibility comes at a cost. Parameter estimations based on LIR can be difficult to interpret and may not be comparable between areas with different sampling regimes. Using a unique data-set from the Philippines with ~8 years of nearly continuous survey effort, we were able to derive a metric for converting LIR residency estimates into more intuitive days-per-year units. We applied this metric to 25 different sites allowing for the first quantitatively-meaningful comparison of sightings-derived residence among the world’s whale shark aggregations. We validated these results against the only three published acoustic residence metrics (falling within the ranges established by these earlier works in all cases). The results were then used to understand residency behaviours exhibited by the sharks at each site. The adjusted residency metric is an improvement to LIR-based population modelling, already one of the most widely used tools for describing whale shark aggregations. The standardised methods presented here can serve as a valuable tool for assessing residency patterns of whale sharks, which is crucial for tailored conservation action, and can cautiously be tested in other taxa.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Improving sightings-derived residency estimation for whale shark aggregations: A novel metric applied to a global data set

Araújo

Agustines

Bach³

et al. 2022

Front. Mar. Sci.

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“…Male whale sharks are likely incentivized to seek out predictable and high-value prey sources to speed their growth to maturity, whereas females may seek out less risky areas elsewhere (Meekan et al, 2020). The apparent absence of adult sharks at Nosy Be lends support to the hypothesis that larger whale sharks are primarily oceanic (Ketchum, Galván-Magaña & Klimley, 2013;Ramírez-Macías et al, 2017;Perry et al, 2020).…”

Section: Discussionmentioning

confidence: 94%

Population structure, residency, and abundance of whale sharks in the coastal waters off Nosy Be, north‐western Madagascar

Diamant

Pierce

Rohner

et al. 2021

Aquatic Conservation

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1. Between September and December, whale sharks (Rhincodon typus) aggregate in the coastal waters off Nosy Be, an island in north-western Madagascar.Swimming with these sharks has become an important tourism activity, but no formal protection is in place in Madagascar to protect this endangered species from the potential negative effects of tourism or other human impacts.2. Boat-based surveys (n = 405) were conducted from tourism vessels from September to December, 2015-2019. For most sightings (98%), whale sharks were sighted while foraging for bait fish at the surface, in association with mackerel tuna (Euthynnus affinis) and seabirds (Sternidae). A total of 408 individual whale sharks were individually photo-identified over this period. All individuals were immature, and 82% of sexed sharks were male. Sharks ranged from 3.0 to 8.0 m in total length (TL), with a mean TL of 5.65 ± 0.94 m (n = 66) for females and 5.46 ± 1.09 m for males (n = 295). 3. Most sharks (72% of the identified individuals) were only identified once within the study period. Movement modelling showed an open population with a short mean residence time of 7.2 days. Resightings were recorded from up to 12 years apart (2007-2019). Ten sharks were seen in all five seasons during 2015-2019. A basic POPAN mark-recapture model estimated a total population size of 681 (608-763) sharks over the 2015-2019 period. 4. Nosy Be waters are an important foraging ground for juvenile whale sharks.Sighting data demonstrate that a high proportion of the sharks' preferred habitat lies outside existing protected areas, but within an identified Key Biodiversity Area. National species-level protection and increased spatial management is warranted to secure the continued presence of whale sharks in this region.

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“…Saint Helena and Ascension Island -two remote, volcanic islands located in the central South Atlantic Ocean, 1,300 km apart -form part of the UKOT of St Helena, Ascension and Tristan da Cunha (Figure 2). When the Blue Belt Programme began in 2016, delivery partners conducted a comprehensive review of scientific data collected by UKOT governments, nongovernmental organizations (NGOs) and research institutions (e.g., Brown, 2014;Weber et al, 2014Weber et al, , 2018Brickle et al, 2017;Nolan et al, 2017;Wirtz et al, 2017;Richardson et al, 2018;Brown et al, 2019;Perry et al, 2020) and an assessment of existing management frameworks. Key evidence gaps were addressed through a targeted science survey program to inform development of the IMM process in collaboration with the UKOT governments.…”

Section: Recognizing the Need For An Integrated Approachmentioning

confidence: 99%

Integrated Marine Management in the United Kingdom Overseas Territories

Hardman¹,

Thomas²,

Baum

et al. 2022

Front. Mar. Sci.

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Like many small island communities, the United Kingdom Overseas Territories (UKOTs) are directly dependent on their marine resources for a range of ecosystem services, such as income generation, subsistence, leisure, recreation and wellbeing. Healthy marine ecosystems also play a broader role in climate regulation, coastal resilience and habitat provision. With Blue Belt Programme assistance, the UKOTs are developing enhanced protection and sustainable management strategies for their marine environments, using an Integrated Marine Management (IMM) approach. This coordinates cross-sectoral planning and management to carefully balance marine conservation and sustainable use of resources in order to minimize socio-cultural and economic impacts to the local community. We describe the IMM approach taken in two UKOT case studies. In Ascension Island, a conservation planning and resource management process was initiated with an objective to protect at least 50% of Ascension’s waters from commercial fishing, resulting in the designation of one of the largest Marine Protected Areas (MPAs) in the Southern Atlantic. In St Helena, a new licensing framework for marine developments was developed within an existing sustainable use MPA. From these two approaches, we highlight aspects of the process, lessons learned and recommendations that may be useful for other small islands planning to implement IMM, particularly regarding the importance of effective stakeholder engagement, coordination across different governance scales, and long-term financial resources.

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St. Helena: An Important Reproductive Habitat for Whale Sharks (Rhincodon typus) in the Central South Atlantic

Cited by 15 publications

References 51 publications

Improving sightings-derived residency estimation for whale shark aggregations: A novel metric applied to a global data set

Improving sightings-derived residency estimation for whale shark aggregations: A novel metric applied to a global data set

Population structure, residency, and abundance of whale sharks in the coastal waters off Nosy Be, north‐western Madagascar

Integrated Marine Management in the United Kingdom Overseas Territories

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