Seasonal distribution of the Indo‐Pacific humpback dolphins: Implications for coastal habitat management

Wang, Chun Chieh; Xu, Youhou; Li, Na; Peng, Chongwei; Wu, Haiping; Huang, Shuqiang

doi:10.1002/aqc.3479

Cited by 7 publications

(5 citation statements)

References 75 publications

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“…Because of the annual ban on fishing in the PRE from May to August, the fish resources during this period are relatively abundant. Abundant fish resources might increase the distribution range of dolphins, thus reducing their sighting rates (Wang et al, 2021).…”

Section: Habitat Decline and Regional Variationsmentioning

confidence: 99%

Habitat decline of the largest known Indo-Pacific humpback dolphin (Sousa chinensis) population in poorly protected areas associated with the hypoxic zone

Guo

Luo²,

Yu³

et al. 2022

Front. Mar. Sci.

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Reserve planning based on the investigation of the core habitat distribution of wild cetaceans is a powerful conservation strategy for protecting target species. However, studies on core habitats and their variations at the large-scale distribution of cetaceans are limited. In this study, we conducted a seven years (2015-2021) boat-based field observation surveys with highly applicable and generalized methods to analyze the habitat changes and how these changes influenced the largest known Indo-Pacific humpback dolphin (Sousa chinensis) population in the Pearl River Estuary (PRE), China. Our findings revealed that there is 3204 km2 of dolphin habitat in the PRE, and dolphin distribution preferences are related to nutrients and biological resources. The decreasing trend of dolphin sighting rates in most areas (73.2%) indicated that the dolphin habitat had declined, and the annual habitat decline rate (2.83%; 95% confidence interval: 0.58%-5.08%) was consistent with the population decline rate. The annual habitat decline rate in the hypoxic zone revealed that low dolphin sighting rates from March to October in the hypoxic zone was 0.43% faster than that in the non-hypoxic zone, indicating long-term sustained effects of summer hypoxia on the dolphin population. Existing reserves have partially prevented habitat decline. However, more than 82.3% of the habitat has not been effectively protected and encounters the threats of pollution and hypoxic stress. This study offers new scientific evidence for developing effective monitoring strategies for humpback dolphin populations in the PRE, and also help establish spatial planning and management measures for reserve habitats.

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Section: Habitat Decline and Regional Variationsmentioning

confidence: 99%

Habitat decline of the largest known Indo-Pacific humpback dolphin (Sousa chinensis) population in poorly protected areas associated with the hypoxic zone

Guo

Luo²,

Yu³

et al. 2022

Front. Mar. Sci.

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“…In each of these studies, prey and predator avoidance have been the most commonly documented drivers for these depth preferences. Areas at these particular depths or gradients have been documented to improve accessibility to demersal fish, and the regional bathymetry profile could positively affect the handling efficacy of catching prey (Durden et al., 2019; Hastie et al., 2003, 2004; Wang et al., 2021; Wu et al., 2017). In this case, demersal fish, such as snapper and King George whiting, are documented prey items of Burrunan dolphins (Filby, Stockin, & Scarpaci, 2017; Owen et al., 2011).…”

Section: Discussionmentioning

confidence: 99%

Population distribution and drivers of habitat use for the Burrunan dolphins, Port Phillip Bay, Australia

Beddoe,

Shimeta,

Klaassen

et al. 2024

Ecology and Evolution

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Bottlenose dolphin (Tursiops) populations, also described as the Burrunan dolphins, consist of a resident population of approximately 150 individuals in Port Phillip Bay (PPB), Victoria. Previous reports indicate distribution across a small southern region of PPB; however, little is known about their full distribution patterns across the entire PPB region. Here, we investigate the spatiotemporal distribution of the Burrunan dolphins across four zones representative of PPB benthic habitats and bathymetry to gain a better understanding of the potential drivers of the population's habitat use. Port Phillip Bay, Victoria, Australia. One hundred and twenty‐nine boat‐based surveys were undertaken between March 2015 and August 2021, encompassing 181 sightings. Generalised linear models (GLMs) were used to investigate annual, seasonal and zonal variation. We found no variation in sighting frequencies between years. Austral summer and winter had a significantly higher sighting frequency than autumn. We found that Burrunan dolphins utilise the entire bay, further extending the species range, and show a significantly higher number of sightings in the southern zone than in any other zones. Overlaying dolphin sightings with known oceanographic characteristics within PPB, we found bathymetry and benthic habitats were potential drivers for the Burrunan dolphins distribution and habitat use within the bay, with the dolphins significantly favouring the 5–10 and 10–15 m contour depths. These results show a more widespread distribution across the bay than previously documented. We recommend expansion of the current marine protected areas in the north and south of the bay. This study has increased our understanding of the vital habitat for the Burrunan dolphin populations. By providing evidence‐based conservation recommendations, we hope to improve and contribute to future research, conservation management plans and effective marine protected areas across PPB for the resident Burrunan dolphin population.

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“…The area under the curve (AUC) of the receiver operating characteristic was used to examine the model performance (Elith et al, 2011). Areas with a cumulative probability greater than 35% were identified as likely core habitat (LCH), and areas with a cumulative probability of 5–35% were identified as likely habitat maxima (LHM) (Bao et al, 2019; Huang et al, 2019; Wang et al, 2021). Areas and distribution patterns of LCH and LHM in the dry and the flood seasons were calculated by ArcMap 10.5 and overlain on the boundaries of the present porpoise nature reserve.…”

Section: Methodsmentioning

confidence: 99%

“…This approach to hydrological and habitat modelling can also be applied to the present and historical habitat simulations for multiple aquatic species, so as to establish a more comprehensive protection network for ecosystem biodiversity and functionality (Li et al, 2021;Paudel et al, 2021). In addition, sound protection of freshwater cetaceans should focus not only on the distribution of these megafaunal habitats, but also the wider integrity of wetland ecosystems (Wang et al, 2021).…”

Section: Implications For Freshwater Cetacean Conservationmentioning

confidence: 99%

Identifying the seasonal characteristics of likely habitats for the Yangtze finless porpoise in Poyang Lake

Lai

Liu

et al. 2022

Aquatic Conservation

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The Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis) has experienced significant decline and habitat degradation in recent decades. At present, nearly half of the total population inhabits Poyang Lake. The hydrological seasonality of the lake significantly influences porpoise habitat configuration, which brings problems for conservation in the delineation of reserve design and the management of human activities. A hydrodynamic model was used to distinguish the different hydrological conditions between the flood and dry seasons. The MaxEnt model was used to investigate the major environmental variables affecting porpoise distribution and delineate likely habitats of the porpoise under different hydrological conditions. The effectiveness of the present nature reserve was evaluated based on these results. Flow velocity and distance to fish spawning grounds were the primary variables influencing porpoise distribution during the dry season. Water depth, flow velocity and the distance to bank were the major variables during the flood season. The likely habitats were distributed discontinuously along the main channel during the dry season, with a total area of 112 km2. During the flood season, the habitats extended into the central areas of the lake and tributaries with a total area of 628 km2. At present, the nature reserve covers 4% and 18% of the likely core habitats during dry and flood seasons. An ideal nature reserve should be designed as an integrative network with reference to the seasonality of likely habitat distribution and major environmental variables. The habitats in conditions of extreme low water should be strictly protected in the dry season. Enhanced survey efforts, long‐term hydrodynamic modelling and species distribution modelling can greatly assist in understanding habitat configuration and changing processes for other freshwater cetaceans inhabiting river–lake systems. Future planning to improve protection should consider habitat characteristics under the shifting hydrological conditions caused by climate change or artificial flow alteration.

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Seasonal distribution of the Indo‐Pacific humpback dolphins: Implications for coastal habitat management

Cited by 7 publications

References 75 publications

Habitat decline of the largest known Indo-Pacific humpback dolphin (Sousa chinensis) population in poorly protected areas associated with the hypoxic zone

Habitat decline of the largest known Indo-Pacific humpback dolphin (Sousa chinensis) population in poorly protected areas associated with the hypoxic zone

Population distribution and drivers of habitat use for the Burrunan dolphins, Port Phillip Bay, Australia

Identifying the seasonal characteristics of likely habitats for the Yangtze finless porpoise in Poyang Lake

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