Abundance, survival and temporary emigration of bottlenose dolphins (Tursiops sp.) off Useless Loop in the western gulf of Shark Bay, Western Australia

Nicholson, Krista; Bejder, Lars; Allen, S. J.; Krützen, Michael; Pollock, Kenneth H.

doi:10.1071/mf12210

Cited by 65 publications

(104 citation statements)

References 44 publications

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“…Dolphin counts did, however, vary among the different surveys, suggesting a substantial detection bias. Other cetacean studies have also observed detection probabilities <1 (Shrestha 1989, Smith et al 1994, Timilsina et al 2003, WWF-Nepal 2006, Paudel et al 2014 and it is appropriate and important to account for these biases when determining population estimates, particularly for rare and endangered species (Nicholson et al 2012). We suggest that future surveys in an N-mixture model framework might benefit from measuring additional detection covariates at the scale of the sites.…”

Section: Discussionmentioning

confidence: 99%

The Endangered Ganges River dolphin Platanista gangetica gangetica in Nepal: abundance, habitat and conservation threats

Paudel¹,

Pal²,

Cove³

et al. 2015

Endang. Species. Res.

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Conservation of the last remaining Ganges River dolphins Platanista gangetica gangetica in Nepal will require robust population estimates and better information on suitable habitat characteristics. To gain a better understanding of these parameters, we conducted boatbased surveys in the 3 major river systems (Karnali, Sapta Koshi, and Narayani) of Nepal. We recorded covariates at high spatial resolution and utilized these data to inform occurrence and abundance models. We allowed for detection bias by applying occupancy and N-mixture models that account for imperfect and heterogeneous detection. Occupancy results indicate that dolphin site use varies among the different river systems, across 2 seasons, and increases with river depth. River effects received nearly 100% of the model support and had the strongest influence on dolphin occurrence and abundance. The seasonal influence on dolphin occurrence in the systems (Σω i = 0.997) revealed that occupancy probabilities were heightened during the pre-monsoon season. Deep pool habitat was also identified as a predictor of dolphin habitat use, which accounted for 41.02% of all dolphin sightings occurring in this habitat. Although estimates vary depending on season, we estimate that there are between 37 and 42 (95% CI: 28 to 52) Ganges River dolphins distributed in the rivers of Nepal. Results suggest that seasonality and each specific river affect dolphins and their habitat in Nepal; we strongly recommend site and season-specific conservation actions. Further research on the integration of additional and alternative abundance techniques, behavioral studies, and pursuit of a conservation genetics approach are all important steps in the management of this endangered species.

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Section: Discussionmentioning

confidence: 99%

The Endangered Ganges River dolphin Platanista gangetica gangetica in Nepal: abundance, habitat and conservation threats

Paudel¹,

Pal²,

Cove³

et al. 2015

Endang. Species. Res.

View full text Add to dashboard Cite

show abstract

“…This might have positive effects on population density, as niche segregation allows for increased carrying capacities compared with ecologically homogeneous populations [51][52][53]. In this context, it is important to note that Shark Bay appears to support one of the highest densities of bottlenose dolphins worldwide, estimated to be 0.53-0.92 dolphins km 22 in parts of the study area in WSB [54].…”

Section: Discussionmentioning

confidence: 99%

Cultural transmission of tool use by Indo-Pacific bottlenose dolphins (Tursiopssp.) provides access to a novel foraging niche

et al. 2014

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Culturally transmitted tool use has important ecological and evolutionary consequences and has been proposed as a significant driver of human evolution. Such evidence is still scarce in other animals. In cetaceans, tool use has been inferred using indirect evidence in one population of Indo-Pacific bottlenose dolphins (Tursiops sp.), where particular dolphins ('spongers') use marine sponges during foraging. To date, evidence of whether this foraging tactic actually provides access to novel food items is lacking. We used fatty acid (FA) signature analysis to identify dietary differences between spongers and non-spongers, analysing data from 11 spongers and 27 non-spongers from two different study sites. Both univariate and multivariate analyses revealed significant differences in FA profiles between spongers and non-spongers between and within study sites. Moreover, FA profiles differed significantly between spongers and non-spongers foraging within the same deep channel habitat, whereas the profiles of non-spongers from deep channel and shallow habitats at this site could not be distinguished. Our results indicate that sponge use by bottlenose dolphins is linked to significant differences in diet. It appears that cultural transmission of tool use in dolphins, as in humans, allows the exploitation of an otherwise unused niche.

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“…Although our study site is not likely to encompass the entire home ranges of some individuals [45] figure S3. In the first column, individuals of both strategies had the same fitness benefits.…”

Section: Discussionmentioning

confidence: 99%

Cultural transmission of tool use combined with habitat specializations leads to fine-scale genetic structure in bottlenose dolphins

et al. 2014

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Socially learned behaviours leading to genetic population structure have rarely been described outside humans. Here, we provide evidence of fine-scale genetic structure that has probably arisen based on socially transmitted behaviours in bottlenose dolphins (Tursiops sp.) in western Shark Bay, Western Australia. We argue that vertical social transmission in different habitats has led to significant geographical genetic structure of mitochondrial DNA (mtDNA) haplotypes. Dolphins with mtDNA haplotypes E or F are found predominantly in deep (more than 10 m) channel habitat, while dolphins with a third haplotype (H) are found predominantly in shallow habitat (less than 10 m), indicating a strong haplotype-habitat correlation. Some dolphins in the deep habitat engage in a foraging strategy using tools. These 'sponging' dolphins are members of one matriline, carrying haplotype E. This pattern is consistent with what had been demonstrated previously at another research site in Shark Bay, where vertical social transmission of sponging had been shown using multiple lines of evidence. Using an individual-based model, we found support that in western Shark Bay, socially transmitted specializations may have led to the observed genetic structure. The reported genetic structure appears to present an example of cultural hitchhiking of mtDNA haplotypes on socially transmitted foraging strategies, suggesting that, as in humans, genetic structure can be shaped through cultural transmission.

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Abundance, survival and temporary emigration of bottlenose dolphins (Tursiops sp.) off Useless Loop in the western gulf of Shark Bay, Western Australia

Cited by 65 publications

References 44 publications

The Endangered Ganges River dolphin Platanista gangetica gangetica in Nepal: abundance, habitat and conservation threats

The Endangered Ganges River dolphin Platanista gangetica gangetica in Nepal: abundance, habitat and conservation threats

Cultural transmission of tool use by Indo-Pacific bottlenose dolphins (Tursiopssp.) provides access to a novel foraging niche

Cultural transmission of tool use combined with habitat specializations leads to fine-scale genetic structure in bottlenose dolphins

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