Surveys of the Angolan coast uncover the largest olive ridley sea turtle nesting population in the Atlantic and the largest non-arribada population globally

Morais, Miguel; Tiwari, Manjula

doi:10.1017/s003060532100065x

Cited by 7 publications

(9 citation statements)

References 20 publications

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“…However, elsewhere in the region a green turtle clutch frequency of 6.0 was determined using satellite tracking, demonstrating the importance of using advanced methods to assess this vital parameter accurately (Esteban et al, 2017). Although the sample size for olive ridley turtles was small, the low clutch frequencies and short remigration intervals are consistent with other non-arribada populations (Miller, 1997; Abreu-Grobois & Plotkin, 2008; Morais & Tiwari, 2022).…”

Section: Discussionsupporting

confidence: 84%

Two decades of community-based conservation yield valuable insights into marine turtle nesting ecology

van de Geer,

Broderick,

Carter

et al. 2024

Oryx

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For the Western Indian Ocean region, there is a significant knowledge gap regarding marine turtle nesting on the continental coast of East Africa. Here we present results from a long-term (2000–2020) community-based monitoring programme in and around Watamu Marine National Park, Kenya, covering 30 km of coastline (c. 6% of the national total). Conservation actions effectively protected nesting turtles and resulted in a near-total cessation of illegal egg harvesting in Watamu Marine National Park. Collected data indicate this is an important marine turtle nesting index site in Kenya and the wider region. Green turtle Chelonia mydas nests were most common (95%), followed by olive ridley turtles Lepidochelys olivacea (4%), with occasional nests of hawksbill Eretmochelys imbricata and leatherback turtles Dermochelys coriacea. Clutches per season increased significantly over the 20-year monitoring period for green turtles (50%) and showed a positive trend for olive ridley turtles. Watamu remains an area at risk from human pressures such as coastal development. Clutch distribution along the Watamu Marine National Park beach has shifted over time, probably because of coastal development and disturbance. Illegal take of adults and eggs continues in areas north and south of the Watamu Marine National Park, possibly slowing rates of recovery. Clutches deemed at risk were moved to a safe location within the National Park, and hatching success was high. Continued conservation efforts, including wider engagement with stakeholders to reduce human pressures, are needed to ensure the perpetuation of this nesting site.

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Section: Discussionsupporting

confidence: 84%

Two decades of community-based conservation yield valuable insights into marine turtle nesting ecology

van de Geer,

Broderick,

Carter

et al. 2024

Oryx

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“…The latter is probably connected to the species distribution and nesting patterns in the Atlantic. Major rookeries are located in Gabon and Angola (Metcalfe et al, 2015; Morais & Tiwari, 2022), but smaller breeding populations exist from Guinea–Bissau southwards, from where they probably disperse into neighbouring countries (Fretey & Malaussena, 1991; Barbosa, Broderick & Catry, 1998). Olive ridley habitat use, movement patterns and foraging behaviour in NW Africa are not well known; however, potential foraging sites exist off Cabo Verde, Senegal, The Gambia, Guinea–Bissau and Sierra Leone (Santos et al, 2019).…”

Section: Discussionmentioning

confidence: 99%

Nowhere to hide: Sea turtle bycatch in Northwest Africa

de la Hoz Schilling,

Diame,

Hernández Ríos

et al. 2023

Aquatic Conservation

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Fisheries bycatch is considered the largest threat to sea turtle populations globally. However, it has been challenging to assess the impact of bycatch on sea turtles in some regions such as Northwest Africa (i.e. Cabo Verde, Guinea, Guinea–Bissau, Mauritania, Senegal, Sierra Leone and The Gambia) owing to large data gaps. This hampers effective management actions and interferes with conservation efforts in the region. Five sea turtle species occur in Northwest Africa (i.e. green turtle Chelonia mydas, hawksbill Eretmochelys imbricata, leatherback Dermochelys coriacea, loggerhead Caretta caretta and olive ridley Lepidochelys olivacea). The region has regionally and globally important sea turtle nesting and foraging habitats and is a global fishing hotspot, with high and increasing fishing pressure. Available information on sea turtle bycatch in Northwest Africa was compiled from peer‐reviewed and grey literature from 2010 onwards to determine the impact of artisanal and industrial fisheries (by gear type) on regional sea turtle populations and assess the level of threat to individual species. All sea turtle species occurring in the region are impacted by bycatch. Reports suggest that green turtles and loggerheads have the highest bycatch rates, probably owing to their regional abundance and widespread distribution. Some of the potentially highest reported global bycatch rates (14,000–90,000 turtles/year/country) are noted, particularly in gillnets, longlines and handlines. However, further research is needed to understand mortality levels from artisanal fisheries and assess the impact of trawl fisheries operating in the region. Additional sources of mortality include deliberate capture for consumption or trade. To strengthen regional sea turtle conservation and reduce sea turtle bycatch and mortality, urgent action is needed to implement and enforce national protection, establish a bycatch reduction framework (including gear modifications and spatio‐temporal closures), improve fisheries data collection and build capacity.

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“…This area is characterized by high rainfall, dense tree cover, beaches with steeper slopes and high wave exposure. On Príncipe, green turtles nest mainly in Praia Grande do Norte Olive Ridley Turtle Major nesting grounds of Olive Ridley Turtles in West Africa are in Angola and Gabon (Metcalfe et al 2015;Morais and Tiwari 2022). Nevertheless, this is the second most numerous species on São Tomé, ranging from 326 to 683 nests per year between 2014 and 2020 (unpublished data).…”

Section: Nesting Beachesmentioning

confidence: 99%

The Sea Turtles of São Tomé and Príncipe: Diversity, Distribution, and Conservation Status

Ferreira-Airaud¹,

Schmitt

Vieira

et al. 2022

Biodiversity of the Gulf of Guinea Oceanic Islands

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The unique islands of São Tomé and Príncipe harbor five of the seven existent sea turtle species, and offer optimal conditions for these threatened species both on the beaches and on the foraging sites at sea. These populations might have been exploited since the sixteenth century and are still being harvested. In the past decade, our knowledge of these populations has greatly improved, highlighting their regional and global importance. Several conservation initiatives have also prioritized their protection. This chapter reviews our knowledge on the diversity, distribution, and conservation status of sea turtles in São Tomé and Príncipe, providing a brief history of conservation actions from the past 20 years and presenting ongoing research and conservation initiatives.

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Surveys of the Angolan coast uncover the largest olive ridley sea turtle nesting population in the Atlantic and the largest non-arribada population globally

Cited by 7 publications

References 20 publications

Two decades of community-based conservation yield valuable insights into marine turtle nesting ecology

Two decades of community-based conservation yield valuable insights into marine turtle nesting ecology

Nowhere to hide: Sea turtle bycatch in Northwest Africa

The Sea Turtles of São Tomé and Príncipe: Diversity, Distribution, and Conservation Status

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