Site fidelity and association patterns of Indo-Pacific humpback dolphins off the east coast of Zhanjiang, China

Xu, Xiaomei; Zhang, Zhenhua; Ma, Lulin; Li, Peng; Yang, Guang; Zhou, Kaiya

doi:10.1007/s13364-011-0058-5

Cited by 27 publications

(40 citation statements)

References 23 publications

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“…Individual variability in site fidelity has also been found in other Australian humpback dolphin populations (Parra et al 2006a, Cagnazzi 2010, Cagnazzi et al 2011, as well as in other humpback dolphin species elsewhere (e.g. Karcz marski et al 1999, Stensland et al 2006, Xu et al 2012.…”

Section: Site Fidelity and Residencymentioning

confidence: 62%

Demographic characteristics of Australian humpback dolphins reveal important habitat toward the southwestern limit of their range

Hunt¹,

Bejder²,

Allen³

et al. 2017

Endang. Species. Res.

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The paucity of information on the recently described Australian humpback dolphin Sousa sahulensis has hindered assessment of its conservation status. Here, we applied capturerecapture models to photo-identification data collected during boat-based surveys between 2013 and 2015 to estimate the abundance, site fidelity and residence patterns of Australian humpback dolphins around the North West Cape (NWC), Western Australia. Using Pollock's closed robust design, abundance estimates varied from 65 to 102 individuals, and POPAN open modelling yielded a super-population size of 129 individuals in the 130 km 2 study area. At approximately 1 humpback dolphin per km 2 , this density is the highest recorded for this species. Temporary emigration was Markovian, suggesting seasonal movement in and out of the study area. Hierarchical clustering showed that 63% of individuals identified exhibited high levels of site fidelity. Analysis of lagged identification rates indicated dolphins use the study area regularly, following a movement model characterised by emigration and re-immigration. These density, site fidelity and residence patterns indicate that the NWC is an important habitat toward the southwestern limit of this species' range. Much of the NWC study area lies within a Marine Protected Area, offering a regulatory framework on which to base the management of human activities with the potential to impact this threatened species. Our methods provide a methodo logical framework to be used in future environmental impact assessments, and our findings represent a baseline from which to develop long-term studies to gain a more complete understanding of Australian humpback dolphin population dynamics.

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Section: Site Fidelity and Residencymentioning

confidence: 62%

Demographic characteristics of Australian humpback dolphins reveal important habitat toward the southwestern limit of their range

Hunt¹,

Bejder²,

Allen³

et al. 2017

Endang. Species. Res.

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“…These are the populations in Leizhou Bay (20 51 0 S; 110 30 0 E) (N ¼ 268 with a 95% confidence interval of 189-413) (Xu et al, 2012), in the Pearl River Estuary of Guangdong (22 16 0 S; 113 43 0 E) (N ¼ 2555 and N ¼ 2517 during wet and dry seasons, respectively) , in Xiamen harbor of Fujian (24 29 0 S; 118 13 0 E) (N ¼ 76; 95% CI ¼ 43-109) (Chen et al, 2009), at the West coast of Taiwan (23 54 0 S; 120 12 0 E) (N ¼ 75; 95% CI ¼ 69-81) (Yu et al, 2010), and in the Beibu Gulf of Guangxi (21 32 0 S; 108 42 0 E) (N ¼ 251; 95% CI ¼ 136-794) (Pan et al, 2006;Chen et al, 2009), respectively. At least two small subpopulations have been discovered at the National Hepu Dugong Nature Reserve in Beibu Gulf: In the Dafeng River Estuary and in Sanniang Bay.…”

Section: Introductionmentioning

confidence: 99%

Whistle characteristics of free-ranging Indo-Pacific humpback dolphins (Sousa chinensis) in Sanniang Bay, China

Wang

Fang

Shi

et al. 2013

The Journal of the Acoustical Society of America

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Broadband recording systems were adapted to characterize the whistle characteristics of free-ranging Indo-Pacific humpback dolphins (Sousa chinensis) in Sanniang Bay, China. A total of 4630 whistles were recorded, of which 2651 with legible contours and relatively good signal-to-noise ratios were selected for statistical analysis. Of the six tonal types (i.e., flat, down, rise, convex, Ushaped, and sine), flat (N ¼ 1426; 39.45%) was the most predominant, followed by down (N ¼ 754; 23.35%) and rise (N ¼ 489; 12.34%). The whistles showed a short duration (mean 6 SD: 370.19 6 285.61 ms; range: 29-2923 ms), a broad frequency range (fundamental contour ranged from 0.52 to 33 kHz), and two harmonics (mean 6 SD: 1.90 6 2.74, with the maximum frequency of harmonics beyond 96 kHz). Whistles without gaps and stairs accounted for 76.7% and 86.4%, respectively. No significant interspecies differences in frequency parameters were observed compared with S. teuszii, which is inconsistent with morphological taxonomies but confirms phylogenetic results, thus suggesting a close relation between Chinese S. chinensis and Atlantic S. teuszii. Significant intra-and interspecific differences in the genus Sousa were also observed, indicating that animal vocalization may not be limited by genetically determined traits but could also be a function of local habitat adaptation.

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“…The previous study that informed the dolphin spatial use was based on a 4‐month short‐term survey (Zhou et al, ), which did not cover the entire spatial use of humpback dolphins in this region. Although the subsequent studies surveyed relatively larger areas (Xu et al, , ), the spatial use of the humpback dolphin population in this region was still not well‐documented. This study firstly documented the spatial use of the world's second largest humpback dolphin population over a 4‐year field visual survey, covering a longer survey period and a larger survey area than previous studies in this region.…”

Section: Discussionmentioning

confidence: 99%

“…The eastern waters off Zhanjiang were selected as the study area based on prior knowledge from earlier studies (Liu, Dong, et al, ; Xu et al, , ; Zhou et al, ; Figure a). The study area consisted predominantly of a shallow water environment (depth 2–40 m) with a sandy/muddy sea floor (Figure b).…”

Section: Methodsmentioning

confidence: 99%

“…In 2007, the local Zhanjiang city government established the 21‐km 2 Zhanjiang Leizhou Bay Municipal Humpback Dolphin Nature Reserve (ZLBMHDNR, 110°26′−110°29′E, 20°44′−110°46′N; Figure a–b) with the aim of providing protection for a population of humpback dolphins in Zhanjiang waters (Xu et al, ; Zhou, Xu, & Tian, ). While intended as a positive conservation action, doubts remain on the efficacy of the ZLBMHDNR in affording adequate protection to dolphins due to its location and size.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Determining spatial use of the world's second largest humpback dolphin population: Implications for place‐based conservation and management

Liu

Bejder

Lin

et al. 2019

Aquatic Conservation

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Place‐based management can be an effective conservation tool to protect cetaceans from anthropogenic pressures. The spatial use of the world's second largest population of the threatened Indo‐Pacific humpback dolphins (Sousa chinensis) is not well‐documented, which makes it challenging to designate protected areas for this population. To address this knowledge gap and to test the efficacy of an existing dolphin protected area (Zhanjiang Leizhou Bay Municipal Humpback Dolphin Nature Reserve, ZLBMHDNR), boat‐based surveys were conducted to document dolphin occurrence from 2015 to 2018, covering an area of 1221 km2 in the eastern waters off Zhanjiang, China. In total, 253 dolphin group sightings were obtained during 174 survey days. Spatial analysis showed that humpback dolphins aggregated in three core‐use areas with higher sighting density within the survey area. Furthermore, intermediate‐use and broad‐use areas were identified that could be essential for the movements of humpback dolphins among these core‐use areas. The spatial usage of humpback dolphins was compared inside and outside the ZLBMHDNR. Results suggest that the ZLBMHDNR is insufficient to encompass a significant portion of dolphin habitat. The ZLBMHDNR (21 km2) is not large enough, and thus it should be expanded for effective place‐based conservation management in this region. For developing a protected area network, important dolphin habitats identified in this study should be protected as a single management unit. Additionally, mitigation of anthropogenic pressures is needed to be taken into consideration as conservation initiatives in the study area. This study provides support for a more science‐informed protected area network, and highlights the necessity of implementing place‐based conservation and management for the world's second largest humpback dolphin population.

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Site fidelity and association patterns of Indo-Pacific humpback dolphins off the east coast of Zhanjiang, China

Cited by 27 publications

References 23 publications

Demographic characteristics of Australian humpback dolphins reveal important habitat toward the southwestern limit of their range

Demographic characteristics of Australian humpback dolphins reveal important habitat toward the southwestern limit of their range

Whistle characteristics of free-ranging Indo-Pacific humpback dolphins (Sousa chinensis) in Sanniang Bay, China

Determining spatial use of the world's second largest humpback dolphin population: Implications for place‐based conservation and management

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