How many dolphins live near a coastal development?

Raudino, Holly C.; Douglas, Corrine; Waples, Kelly

doi:10.1016/j.rsma.2018.03.004

Cited by 8 publications

(18 citation statements)

References 47 publications

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“…In this study, our "trap arrangement" were non-random transects with an opposing zig-zag layout which remained constant and uniform throughout the study and had an average density of 0.8 transects per km 2 . Population density estimated from the POPAN abundance estimate was an average of 2.4 IP bottlenose dolphins per km 2 , which is relatively high compared with populations in similar sized study areas (Möller et al, 2002;Nicholson et al, 2012;Smith et al, 2013;Brown et al, 2016;Raudino et al, 2018). POPAN estimated capture probabilities at an average of 0.44 (0.33-0.55) with less than 50% of individuals likely to be recaptured in each sampling period suggesting individual heterogeneity and transience, violating the model assumption that individuals were equally likely to be captured.…”

Section: Model Selection and Evaluation Of Model Reliability And Perfmentioning

confidence: 82%

“…The presence of IP bottlenose dolphins in coastal waters adjacent to the NWC (Haughey, personal observations), and further offshore within the central and eastern parts of the Exmouth Gulf (Preen et al, 1997;Sleeman et al, 2007;Hanf, 2015), as well as in Coral Bay to the south and Onslow to the north (approx. 100 km either direction) Raudino et al, 2018) suggest that movements beyond the study area are likely. Future monitoring of IP bottlenose dolphins integrating photo-identification, genetics, and telemetry in NWC and adjacent waters would shed further insight into their population boundaries, site fidelity and home range.…”

Section: Site Fidelitymentioning

confidence: 95%

“…Differences in the methodologies used and sizes of study areas makes comparison of abundance estimates amongst studies difficult. Most estimates of abundance for other areas in Australia of similar size to our study area (130 km 2 ) and generated using similar methodologies (photo-identification and capture-recapture models) range in size from 63 individuals to 160 individuals (Möller et al, 2002;Smith et al, 2013;Brown et al, 2016;Raudino et al, 2018) with the exception of Point Lookout, Australia, with estimates of 861-895 individuals (Chilvers et al, 2003). The NWC abundance estimates of 311-370 individuals are larger than most of these studies and thus indicate a moderately large population inhabits these waters.…”

Section: Abundance Of Individualsmentioning

confidence: 97%

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Photographic Capture-Recapture Analysis Reveals a Large Population of Indo-Pacific Bottlenose Dolphins (Tursiops aduncus) With Low Site Fidelity off the North West Cape, Western Australia

et al. 2020

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Little is known about the ecology of Indo-Pacific bottlenose dolphins (Tursiops aduncus) inhabiting the coastal waters of tropical north-western Australia. We used photoidentification data collected between 2013 and 2015, site fidelity indexes and capturerecapture models to estimate the abundance and site fidelity patterns of Indo-Pacific bottlenose dolphins (T. aduncus) inhabiting the coastal waters off the North West Cape (NWC), Western Australia. A standardized site fidelity index (SSFI) indicated low site fidelity (SSFI = 0.019) at the population level to the 130 km 2 study area. Agglomerative hierarchical clustering (AHC) of individual re-sight rates classified 58% of individuals as "non-residents." Open POPAN modeling estimated a super-population size of 311 (95% CI: 249-373) individuals over the study period. A maximum likelihood transient model which considers both resident and non-resident individuals in a population, estimated a resident population of 141 (95% CI: 121-161) individuals and a super-population of 370 (95% CI: 333-407) individuals. These models indicate that a large population of Indo-Pacific bottlenose dolphins of relatively high density (an average of 2.4-2.8 bottlenose dolphins per km 2 ) inhabits the waters off the NWC. The large number of both resident and non-resident bottlenose dolphins found throughout the coastal waters off the NWC suggest this area, as well as neighboring waters outside our study area, are of high importance to this species.

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Section: Model Selection and Evaluation Of Model Reliability And Perfmentioning

confidence: 82%

Section: Site Fidelitymentioning

confidence: 95%

Section: Abundance Of Individualsmentioning

confidence: 97%

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Photographic Capture-Recapture Analysis Reveals a Large Population of Indo-Pacific Bottlenose Dolphins (Tursiops aduncus) With Low Site Fidelity off the North West Cape, Western Australia

et al. 2020

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“…The limited survey effort that has been undertaken in this area restricts our current understanding of population abundance and potential range including connectivity with the population present in Pilbara coastal waters. We have identified a relatively high number of individual humpback dolphins with minimal survey effort compared to other sites where there has been repeated survey effort in the Pilbara (Raudino et al 2018) and Kimberley (Brown et al 2016b). It is highly probable that more humpback dolphins will be identified using these offshore islands with future survey effort in favourable environmental conditions.…”

Section: Discussion/conclusionmentioning

confidence: 83%

“…calves were in baby position with an adult assumed to be the mother (Mann and Smuts 1998), juveniles were larger than calves but smaller than adults and appeared to be independent of an adult (Parra et al 2006c). Photographs from both opportunistic sightings and dedicated surveys were processed, entered into a State-wide database ('Dolfin'), and compared to the existing catalogue of humpback dolphins for Western Australia (Raudino et al, 2018).…”

Section: Methodsmentioning

confidence: 99%

Records of Australian humpback dolphins (Sousa sahulensis) from an offshore island group in Western Australia

2018

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We report records of humpback dolphins at the Montebello Islands (20°26'S, 115°33′E) approximately 80 km from the mainland coast of Western Australia. This island group is a marine protected area (MPA), with approximately half of the area a sanctuary (no take) zone managed solely for nature conservation that excludes activities such as fishing and resource extraction, activities known to impact dolphins elsewhere. The habitat varies but includes fringing coral reef and shallow, sheltered sandy lagoons mostly < 10 m water depth and not exceeding 20 m. Several opportunistic sightings and one targeted five-day survey have resulted in 28 dolphins being catalogued in the MPA through photo-identification of natural marks on the dorsal fin and are considered to be recognisable through either distinctive or subtle marks. The species was initially reported in the MPA in June 2015 and was present in summer, autumn and winter of 2017. Six calves have been observed in the MPA, with one a neonate. Given the recent listing of the species as Vulnerable on the IUCN Redlist, and increasing pressure on near-shore coastal habitat, recognising the presence of this species at offshore islands such as these, and understanding their status and connectivity is a priority for the conservation and management of the species in Western Australia.

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Evidence of male alliance formation in a small dolphin community

et al. 2022

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The photo-identification of uniquely marked individuals has revealed much about mammalian behaviour and social structure in recent decades. In bottlenose dolphins (Tursiops spp.), for example, the long-term tracking of individuals has unveiled considerable variation in social structure among populations and various spatio-temporal aspects of group formation. In this study, we investigated associations among individual males in a small community of Indo-Pacific bottlenose dolphins (T. aduncus) residing in an urbanized estuary in southwestern Australia. Given the relative proximity of our study area to other populations in which complex male alliances form for the purpose of mate acquisition, we used long-term photo-identification records and social analyses to assess whether such alliances also occur in smaller and more isolated settings. Our work revealed strong social bonds and long-term, non-random associations among individual males, suggesting the occurrence of male alliances. Behavioural observations of alliances interacting with potentially receptive adult females from the estuary community and from adjacent communities, and exhibiting sexual display behaviours near females, suggest that these alliances occur in a reproductive context. As the first formal analysis indicating the occurrence of male alliances outside Shark Bay along the vast western coastline of Australia, this study complements previous research and extends our understanding of the evolutionary and ecological processes that drive alliance formation.

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How many dolphins live near a coastal development?

Cited by 8 publications

References 47 publications

Photographic Capture-Recapture Analysis Reveals a Large Population of Indo-Pacific Bottlenose Dolphins (Tursiops aduncus) With Low Site Fidelity off the North West Cape, Western Australia

Photographic Capture-Recapture Analysis Reveals a Large Population of Indo-Pacific Bottlenose Dolphins (Tursiops aduncus) With Low Site Fidelity off the North West Cape, Western Australia

Records of Australian humpback dolphins (Sousa sahulensis) from an offshore island group in Western Australia

Evidence of male alliance formation in a small dolphin community

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