Distribution, abundance, and individual movements of Indo-Pacific humpback dolphins (<i>Sousa chinensis</i>) in the Pearl River Estuary, China

Chen, Tao; Hung, Samuel K.; Qiu, Yongsong; Jia, Xiaoping; Jefferson, Thomas A.

doi:10.1515/mamm.2010.024

Cited by 97 publications

(118 citation statements)

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“…The Pearl River Estuary shelters the world's largest known population of Indo-Pacific humpback dolphins (Chen et al 2010;Jefferson & Smith 2016;Preen 2004), with an estimated population of 2637 (Coefficient of variation of 19% to 89%) (Chen et al 2010;Jefferson & Smith 2016). The general preference of this species for estuarine habitats and coastal and shallow water (<30 m depth) distribution make it susceptible to the impacts of human activity (Jefferson & Smith 2016).…”

Section: Passive Hearing By the Dolphinmentioning

confidence: 99%

Diversity of fish sound types in the Pearl River Estuary, China

Wang

Nowacek

Akamatsu

et al. 2017

Preprint

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Background. Repetitive species-specific sound enables the identification of the presence and behavior of soniferous species by acoustic means. Passive acoustic monitoring has been widely applied to monitor the spatial and temporal occurrence and behavior of calling species. Methods. Underwater biological sounds in the Pearl River Estuary, China, were collected using passive acoustic monitoring, with special attention paid to fish sounds. A total of 1408 suspected fish calls comprising 18,942 pulses were qualitatively analyzed using a customized acoustic analysis routine. Results. We identified a diversity of 66 types of fish sounds. In addition to single pulse, the sounds tended to have a pulse train structure. The pulses were characterized by an approximate 8 ms duration, with a peak frequency from 500 to 2600 Hz and a majority of the energy below 4000 Hz. The median inter-pulsepeak interval (IPPI) of most call types was 9 or 10 ms. Most call types with median IPPIs of 9 ms and 10 ms were observed at times that were exclusive from each other, suggesting that they might be produced by different species. According to the literature, the two section signal types of 1+1 and 1+N 10 might belong to big-snout croaker (Johnius macrorhynus), and 1+N 19 might be produced by Belanger's croaker (J. belangerii).Discussion. Categorization of the baseline ambient biological sound is an important first step in mapping the spatial and temporal patterns of soniferous fishes. The next step is the identification of the species producing each sound. The distribution pattern of soniferous fishes will be helpful for the protection and management of local fishery resources and in marine environmental impact assessment. Since the local vulnerable Indo-Pacific humpback dolphin (Sousa chinensis) mainly preys on soniferous fishes, the fine-scale distribution pattern of soniferous fishes can aid in the conservation of this species.Additionally, prey and predator relationships can be observed when a database of species- AbstractBackground. Repetitive species-specific sound enables the identification of the presence and behavior of

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Section: Passive Hearing By the Dolphinmentioning

confidence: 99%

Diversity of fish sound types in the Pearl River Estuary, China

Wang

Nowacek

Akamatsu

et al. 2017

Preprint

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“…Humpback dolphins inhabiting coastal waters of the Pearl River Estuary (PRE) are thought to number ca . 2,500 individuals [38] (although this estimate has to be viewed cautiously [25]), which makes them the largest population of this species along the Chinese coast [39], possibly the largest in the whole of southeast Asia. This population, however, is under a tremendous anthropogenic pressure.…”

Section: Introductionmentioning

confidence: 99%

Indo-Pacific humpback dolphins (Sousa chinensis) in Hong Kong: Modelling demographic parameters with mark-recapture techniques

Chan

Karczmarski

2017

PLoS ONE

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Indo-Pacific humpback dolphins (Sousa chinensis) inhabiting Hong Kong waters are thought to be among the world's most anthropogenically impacted coastal delphinids. We have conducted a 5-year (2010–2014) photo-ID study and performed the first in this region comprehensive mark-recapture analysis applying a suite of open population models and robust design models. Cormack-Jolly-Seber (CJS) models suggested a significant transient effect and seasonal variation in apparent survival probabilities as result of a fluid movement beyond the study area. Given the spatial restrictions of our study, limited by an administrative border, if emigration was to be considered negligible the estimated survival rate of adults was 0.980. Super-population estimates indicated that at least 368 dolphins used Hong Kong waters as part of their range. Closed robust design models suggested an influx of dolphins from winter to summer and increased site fidelity in summer; and outflux, although less prominent, during summer-winter intervals. Abundance estimates in summer (N = 144–231) were higher than that in winter (N = 87–111), corresponding to the availability of prey resources which in Hong Kong waters peaks during summer months. We point out that the current population monitoring strategy used by the Hong Kong authorities is ill-suited for a timely detection of a population change and should be revised.

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“…In southern and central Chinese waters, there are two populations currently receiving high research attention: one located in the Pearl River Estuary (PRE) near Hong Kong (Jefferson 2000), and the critically endangered eastern Taiwan Strait (ETS) population found along central western Taiwan (Wang et al 2004). The PRE population consists of over 2500 individuals (Chen et al 2010), but a subset of 200-300 dolphins are known to use the waters just off Hong Kong, principally surrounding Lantau Island and the Hong Kong International Airport (S.K. Hung, personal communication).…”

Section: Introductionmentioning

confidence: 99%

Two social communities in the Pearl River Estuary population of Indo-Pacific humpback dolphins (Sousa chinensis)

Dungan

Hung²,

Wang

et al. 2012

Can. J. Zool.

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The way human activities impact animal populations can depend on social structure, which is important to understand in social species such as cetaceans. We investigated association patterns in Indo-Pacific humpback dolphins (Sousa chinensis (Osbeck, 1765)) inhabiting the Pearl River Estuary near Lantau Island, Hong Kong, using a 10-year data set for 88 individuals. Our analyses revealed two social communities. Each had its own region of core use, to the north and to the west of the island, but their overall ranges partially overlapped northwest of Lantau. The northern community had a fissionfusion structure characterized by short-term associations, while the western community had more long-term associations. Mixed-community groups included calves more often than exclusive groups, so between-community associations may arise from common habitat usage, by females especially, in the overlap area. Recent range extensions by the northern community into the west are likely a response to habitat destruction north of Lantau. This suggests ease of movement between the north and the west is necessary for northern-community dolphins to access suitable habitat, and gives new concern to construction projects planned for the region. We emphasize our study as an example of how sociobiological information can be important in understanding human impacts on animal populations.

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Distribution, abundance, and individual movements of Indo-Pacific humpback dolphins (Sousa chinensis) in the Pearl River Estuary, China

Cited by 97 publications

References 24 publications

Diversity of fish sound types in the Pearl River Estuary, China

Diversity of fish sound types in the Pearl River Estuary, China

Indo-Pacific humpback dolphins (Sousa chinensis) in Hong Kong: Modelling demographic parameters with mark-recapture techniques

Two social communities in the Pearl River Estuary population of Indo-Pacific humpback dolphins (Sousa chinensis)

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