An unknown component of a well-known population: socio-demographic parameters of Indo-Pacific humpback dolphins (Sousa chinensis) at the western reaches of the Pearl River Delta region

Spatiotemporal dynamics of the social structure of Indo-Pacific humpback dolphins (<i>Sousa chinensis</i>) in Xiamen waters from 2007 to 2019

“…This structure can affect many aspects of a population, including its growth, genetics, and movements ( Whitehead, 2009 ). Consequently, exploring the social structure of group-living animals is vital for understanding their ecological characteristics and for informing their conservation and management strategies ( Chan et al, 2022 ; Davies et al, 2012 ; Parra et al, 2011 ).…”

“…Indo-Pacific humpback dolphins ( Sousa chinensis ), which inhabit coastal areas, exhibit a fission-fusion social pattern. Populations of S. chinensis in the Pearl River Estuary ( Chan et al, 2022 ; Dungan et al, 2012 ) and eastern Taiwan Strait ( Sousa chinensis taiwanensis ) ( Dungan et al, 2016 ; Wang et al, 2015a ) are reported to form distinct clusters and display strong intra-cluster associations. In contrast, populations in the waters of Hong Kong and Zhanjiang appear to show more casual and short-term associations ( Jefferson, 2000 ; Jefferson & Karczmarski, 2001 ; Xu et al, 2012 ).…”

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

“…With time, however, it became increasingly evident that further studies of population processes of the PRD dolphins were much needed and at spatio-analytical scales that could provide a considerably greater data resolution than the early work could offer (Karczmarski et al, 2016). Some such studies have recently been completed and indicate a distinct socio-spatial and demographic structure of the dolphin population across the PRD (Chan, 2019;Guo et al, 2020;Chan et al, 2022a), and further fine-scale socio-spatial structure within LB where multiple clusters interact socially but remain considerably dissimilar spatially (Karczmarski et al unpublished 2 ). Various environmental factors also vary spatially in LB.…”

“…Early studies of humpback dolphins in China applied primarily line-transect techniques to collect information such as relative abundance and distribution (e.g., Jefferson, 2000;Hung and Jefferson, 2004;Chen et al, 2008;Chen et al, 2010). Recent studies have increasingly used mark-recapture techniques for more advanced demographic analyses (e.g., Chan and Karczmarski, 2017;Chen et al, 2018;Zeng et al, 2020;Chan et al, 2022a;Lin et al, 2022;Chan and Karczmarski, 2024). Mark-recapture population modeling techniques not only deliver robust estimates of demographic parameters with considerable accuracy (e.g., Hastings et al, 2011;Pace et al, 2017;Kendall et al, 2019;Oosthuizen et al, 2019a;Schleimer et al, 2019;Bright Ross et al, 2022), but provide also powerful tools to identify the underlying driver(s) of ecological and demographic processes (e.g., Horswill et al, 2014;Oosthuizen et al, 2019b;Coxon et al, 2022;Gabriele et al, 2022;Marneweck et al, 2022;Jordaan et al, 2023) and offer a flexible framework for population monitoring that is both effective and reliable, and applicable across a wide range of taxa and management needs (e.g., Atkinson et al, 2021;Chan et al, 2022b;Goldenberg et al, 2022;Szott et al, 2022;Verborgh et al, 2022).…”

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

“…Nowadays, photographic identification of individual animals (individual photo-ID), based on naturally occurring, distinctive and individual-specific marking is a wellestablished and widely used research technique. 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.…”