Individual identification and photographic techniques in mammalian ecological and behavioural research—Part 2: Field studies and applications

Karczmarski, Leszek; Chan, Stephen C. Y.; Chui, Scott Y. S.; Cameron, Elissa Z.

doi:10.1007/s42991-023-00344-9

Cited by 25 publications

(2 citation statements)

References 99 publications

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“…From January 2011 to December 2015, when sea conditions and weather allowed (sea state ≤ 3 in Beaufort scale and visibility ≥ 1 km), boat-based photo-identification surveys were carried out concurrently in Guangdong and Hong Kong waters, following internationally recognized protocol (e.g., Hammond et al, 1990;Karczmarski et al, 2022a;Karczmarski et al, 2022b). Once a group of dolphins was encountered, the research vessels approached the animals at speed ≤6 km/h.…”

Section: Data Collection and Photographic Identificationmentioning

confidence: 99%

Population parameters and heterogeneity in survival rates of Indo-Pacific humpback dolphins in a heavily urbanized coastal region of southeast China: implications for conservation

Lin,

Karczmarski,

Chan

et al. 2024

Front. Mar. Sci.

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The Pearl River Delta (PRD) region on the southeast coast of China is among the largest and most populated metropolitan regions of the world, subjecting the Indo-Pacific humpback dolphins (Sousa chinensis) inhabiting coastal waters of this region – apparently the largest population of this species – to intense anthropogenic pressure. In this 5-year study (2011-2015), we applied mark-recapture techniques to quantify population parameters of humpback dolphins in the main body of the extensive estuarine system of the Pearl River, the Lingding Bay (LB), the most urbanized and industrialized part of PRD. The super-population size was estimated at 928 individuals (95% CI=823-1046), which however over-represents the latest number of extant animals. Annual estimates fluctuated between 708 and 750 dolphins, and likely reflect most accurately the latest/current number of humpback dolphins in waters of LB. Both the overall and annual estimates generated by our study are considerably lower than previously published abundance estimates. Apparent survival rates were generally low, estimated at 0.943 (SE = 0.008, 95% CI = 0.929-0.958) and 0.815 (SE = 0.025, 95% CI = 0.766-0.866) for adults and juveniles, respectively. In conjunction with limited recruitment, they may have led to a substantial decline in population numbers over the past two decades. Notably, dolphins exhibited heterogeneous apparent survival rates across the complex anthropogenic seascape of LB. Adult individuals that use Hong Kong waters as their primary habitat exhibited 6.2% higher survival rates than those in other parts of LB. This difference tripled (19.2%) for juveniles, a likely expression of their susceptibility to environmental and/or anthropogenic stresses. We suggest that the difference in survival is largely due to heterogeneous anthropogenic stressors that vary spatially across the estuary, among which habitat loss, pollution, and declining prey resources appear to be the primary threats. Based on our latest findings, we call for a strategic conservation planning with the highest priority given to preserve the remaining key dolphin habitats in Hong Kong waters, and to quantify and mitigate the impacts of major stressor(s) in Guangdong (mainland China) waters. Given the encroachment of ever-more-intense human activities on the coastal habitats of humpback dolphins, understanding their demographic response and the underlying mechanisms of the population processes may prove instrumental in the formulation of a conservation management strategy that can secure their continuous survival.

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Section: Data Collection and Photographic Identificationmentioning

confidence: 99%

Population parameters and heterogeneity in survival rates of Indo-Pacific humpback dolphins in a heavily urbanized coastal region of southeast China: implications for conservation

Lin,

Karczmarski,

Chan

et al. 2024

Front. Mar. Sci.

Self Cite

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“…It has been applied across a range of taxa, from insects (Coleoptera, e.g., Romiti et al 2017;Díaz-Calafat et al 2018), to amphibians (e.g., Bendik et al 2013;Mettouris et al 2016;Patel and Das 2020), reptiles (e.g., Treilibs et al 2016;Gatto et al 2018;Araujo et al 2019;Desai et al 2022), various species of elasmobranchs (e.g., Holmberg et al 2009;Hughes and Burghardt 2017;Benjamins et al 2018;Armstrong et al 2019;Lewis et al 2020), birds (e.g., Ferreira et al 2020, and numerous species of mammals, both marine and terrestrial (e.g., Tavares et al 2017;Muller 2018;Koivuniemi et al 2019;Turner et al 2021;Chan et al 2022aChan et al , 2022bMarneweck et al 2022;Oberosler et al 2022;Reed et al 2022). While the type of individually distinctive marking may differ between taxa (e.g., pattern of spots and stripes, notches on flukes and fins, facial features or morphometric characteristics; e.g., Karczmarski et al 2022aKarczmarski et al , 2022b, the technique has proven to be a powerful yet non-intrusive tool in field studies of animal behaviour, ecology, and various aspects of their biology.…”

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confidence: 99%

Application of multi-species photo-ID database management systems: a user’s perspective

2022

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Advanced image recognition: a fully automated, high-accuracy photo-identification matching system for humpback whales

Cheeseman

Southerland²,

Park³

et al. 2021

Mamm Biol

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Individual identification and photographic techniques in mammalian ecological and behavioural research—Part 2: Field studies and applications

Cited by 25 publications

References 99 publications

Population parameters and heterogeneity in survival rates of Indo-Pacific humpback dolphins in a heavily urbanized coastal region of southeast China: implications for conservation

Population parameters and heterogeneity in survival rates of Indo-Pacific humpback dolphins in a heavily urbanized coastal region of southeast China: implications for conservation

Application of multi-species photo-ID database management systems: a user’s perspective

Advanced image recognition: a fully automated, high-accuracy photo-identification matching system for humpback whales

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