Habitat selection of two island-associated dolphin species from the south-west Indian Ocean

Condet, Manon; Dulau-Drouot, Violaine

doi:10.1016/j.csr.2016.06.010

Cited by 15 publications

(18 citation statements)

References 59 publications

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“…Transects were not pre-defined but were directed to cover the bathymetry range of the habitat of T . aduncus (waters less than 100 m deep) [ 26 , 36 ]. Upon an encounter, the GPS position was recorded, the group size and number of newborn calves were estimated and photographs were taken for individual identification.…”

Section: Methodsmentioning

confidence: 99%

“…Being a young volcanic island, the underwater relief is very steep, confining the dolphins’ habitat to a very narrow band near the coastline, within 1.2 km from the coast on average [26]. The species is present year-round, with no apparent seasonal changes in sighting frequency [36].…”

Section: Introductionmentioning

confidence: 99%

“…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 ]. No offshore sightings have been documented, and little is known about any potential movement into the open ocean.…”

Section: Introductionmentioning

confidence: 99%

“…Off the oceanic island of Reunion, in the Indian Ocean (55°E33’/21°S07’), the local population of Indo-Pacific bottlenose dolphins is considered as under threat, mainly due to the ongoing and foreseen habitat degradation related to the economic development of this French overseas territory [ 35 ]. Being a young volcanic island, the underwater relief is very steep, confining the dolphins’ habitat to a very narrow band near the coastline, within 1.2 km from the coast on average [ 26 ]. The species is present year-round, with no apparent seasonal changes in sighting frequency [ 36 ].…”

Section: Introductionmentioning

confidence: 99%

“…Currently, a growing emphasis on coastal planning and an associated large number of development projects in the marine environment (e.g. harbour extension, embankments, road construction, and renewable energy) is leading to direct loss and/or fragmentation of the dolphins’ core habitat [ 26 ]. Likewise, being confined to coastal waters, the species appears to be particularly exposed to anthropogenic pollution discharged by rivers and surface runoff [ 37 ].…”

Section: Introductionmentioning

confidence: 99%

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

Dulau

Estrade

Fayan³

2017

PLoS ONE

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Photo-identification surveys of Indo-Pacific bottlenose dolphins were conducted from 2009 to 2014 off Reunion Island (55°E33’/21°S07’), in the Indian Ocean. Robust Design models were applied to produce the most reliable estimate of population abundance and survival rate, while accounting for temporary emigration from the survey area (west coast). The sampling scheme consisted of a five-month (June–October) sampling period in each year of the study. The overall population size at Reunion was estimated to be 72 individuals (SE = 6.17, 95%CI = 61–85), based on a random temporary emigration (γ”) of 0.096 and a proportion of 0.70 (SE = 0.03) distinct individuals. The annual survival rate was 0.93 (±0.018 SE, 95%CI = 0.886–0.958) and was constant over time and between sexes. Models considering gender groups indicated different movement patterns between males and females. Males showed null or quasi-null temporary emigration (γ” = γ’ < 0.01), while females showed a random temporary emigration (γ”) of 0.10, suggesting that a small proportion of females was outside the survey area during each primary sampling period. Sex-specific temporary migration patterns were consistent with movement and residency patterns observed in other areas. The Robust Design approach provided an appropriate sampling scheme for deriving island-associated population parameters, while allowing to restrict survey effort both spatially (i.e. west coast only) and temporally (five months per year). Although abundance and survival were stable over the six years, the small population size of fewer than 100 individuals suggested that this population is highly vulnerable. Priority should be given to reducing any potential impact of human activity on the population and its habitat.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

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

Dulau

Estrade

Fayan³

2017

PLoS ONE

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Effects of swim‐with‐dolphin tourism on the behaviour of spinner dolphins, at Samadai Reef in the Egyptian Red Sea

Shawky¹,

Christiansen

Ormond

2020

Aquatic Conservation

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1. Spinner dolphins, Stenella longirostris, are the primary target for marine mammal tourism in Egypt. The present study investigated the short-term effects of tourist presence on the behaviour of spinner dolphins at Sha'ab Samadai (Samadai Reef), in the southern Egyptian Red Sea.2. The reef has a large central lagoon where a population of spinner dolphin regularly rest from mid-morning to mid-afternoon; visitors are permitted to snorkel in the southern part of the lagoon, but not in the northern closed zone that the dolphins mainly use.3. Dolphin behaviour was monitored both on days when tourist boats were present and on days when they were absent. In the presence of tourists the proportion of time that the dolphins spent resting was reduced by two-thirds, whereas the times spent milling, travelling, and showing avoidance behaviour all increased. 4. Furthermore, upon using Markov chain modelling to investigate the effect of tourist presence on the transition probabilities between dolphin activity states, significant changes were found in 10 of the 25 possible behavioural transitions, including increased probabilities of transitioning from resting to milling or travelling, from milling to travelling or avoiding, and from travelling to avoiding. 5. These findings raise concerns that despite the management measures in place, tourist activities affect the dolphins' behaviour to a greater extent than was previously apparent, with potential long-term negative effects on their energy budget.The study led to proposals for amending the zoning of the site and for strengthening the regulations for tourist vessels.

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Spinner Dolphins of Islands and Atolls

Lammers

2019

Ethology and Behavioral Ecology of Odontocetes

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Habitat selection of two island-associated dolphin species from the south-west Indian Ocean

Cited by 15 publications

References 59 publications

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

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

Effects of swim‐with‐dolphin tourism on the behaviour of spinner dolphins, at Samadai Reef in the Egyptian Red Sea

Spinner Dolphins of Islands and Atolls

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