Capture-mark-recapture modelling suggests an Endangered status for the Mayotte Island (eastern Africa) population of Indo-Pacific bottlenose dolphins

Abstract

We evaluated whether the Indo-Pacific bottlenose dolphins around the fast-developing island of Mayotte are threatened. We used opportunistic photo-identification data and capture-mark-recapture models to estimate key demographic parameters and then assessed the conservation status of the species using the IUCN Red List regional criteria. The population home range was estimated with the minimum convex polygon method as 978 km 2 , the annual abundance was estimated from closed population models as 82 ±19 SE individuals and the annual survival rate was estimated using a Cormack-Jolly-Seber model as 0.937 ± 0.059 SE. From the data available, we believe migrations of individuals between Mayotte and its neighbouring islands are likely but would not exceed a few individuals per year. Based on IUCN guidelines for classification at local scales, we classified Indo-Pacific bottlenose dolphins around Mayotte as Endangered. We strongly recommend the establishment of a long-term population-monitoring program and the implementation of management measures.

Identifying key demographic parameters of a small island–associated population of Indo-Pacific bottlenose dolphins (Reunion, Indian Ocean)

“…aduncus in Reunion was found to be small (71 individuals, 95%CI: 60–84). This is consistent with abundance estimates produced for other oceanic islands of similar size, such as Mayotte and Mauritius [ 17 , 18 ], although direct comparisons are difficult due to the different methods used (models and size of the survey area). For Reunion, the abundance estimate of the overall population refers to a spatial range of around 786 km 2 (waters < 100 m deep).…”

“…Because of their confined coastal habitat and high residency, Indo-Pacific bottlenose dolphins, Tursiops aduncus , are particularly well-suited for mark–recapture monitoring. Within its range, the species seems to exhibit strong year-round residency and occur in small, local populations of usually a few hundred individuals [ 8 , 9 , 11 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ], although estimates of up to thousands of individuals have been produced in some regions [ 21 , 22 , 23 ]. The species is found almost exclusively near the shore, generally in waters less than 100 m deep [ 19 , 24 , 25 , 26 ].…”

Marine megafauna interactions with small-scale fisheries in the southwestern Indian Ocean: a review of status and challenges for research and management

“…To date population abundances have only been estimated for two cetacean species in restricted areas of the SWIO: Indian Ocean humpback (Sousa plumbea) and IndoPacific bottlenose dolphins (Tursiops aduncus) in the Pauly and Zeller (2015) Menai Bay Conservation Area off the south coast south of Unguja Island, Zanzibar and in the KisiteMpunguti Marine Protected Area (MPA), Kenya (Meyler et al 2012;Pérez-Jorge et al 2015Stensland et al 2006); and T. aduncus off the southwest of Mauritius (Webster et al 2014), around Mayotte (Pusineri et al 2014) and La Réunion (Dulau et al 2017). Capture rate estimates are only available for Zanzibar, with these showing unsustainable levels of fisheries mortality for both species (Amir 2010;Amir et al 2002).…”

Temporal–spatial distribution of an island‐based offshore population of common bottlenose dolphins (Tursiops truncatus) in the equatorial Atlantic

“…), Cape Verde (Hazevoet et al . ), Coco's Island (Acevedo and Würsig ), Mayotte island (Pusineri ), St. Helena (MacLeod and Bennet ), and São Tomé and Príncipe (Pereira et al . ).…”

“…A study comparing mtDNA and microsatellite DNA from seven different populations suggested local founder events in some cases and showed significant genetic differentiation due restricted gene flow (Natoli et al 2004). Ecological aspects of island-based oceanic populations have also been studied at Ascension Island (Perrin 1985), Belize (Campbell et al 2002), Bermuda (Klatsky et al 2007), Cape Verde (Hazevoet et al 2010), Coco's Island (Acevedo and W€ ursig 1991), Mayotte island (Pusineri 2014), St. Helena (MacLeod and Bennet 2007), and São Tom e and Pr ıncipe (Pereira et al 2012).…”