Entity

Time filter

Source Type


Dungan S.Z.,Trent University | Hung S.K.,Hong Kong Cetacean Research Project | Wang J.Y.,FormosaCetus Research and Conservation Group | Wang J.Y.,Trent University | White B.N.,Trent University
Canadian Journal of Zoology | Year: 2012

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 fission- fusion 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. Source


Wang J.Y.,FormosaCetus Research and Conservation Group | Wang J.Y.,Trent University | Wang J.Y.,George Mason University | Yang S.C.,FormosaCetus Research and Conservation Group | And 2 more authors.
Mammalia | Year: 2010

The existence of at least two biological species of finless porpoises (Neophocaena phocaenoides and N. asiaeorientalis) was accepted only recently. Given the vulnerability of finless porpoises to human activities throughout their distribution, it is crucial that the two species be distinguished during field studies to better understand their biology and conservation status. Because finless porpoises are notoriously difficult to detect and to photograph at sea owing to their intrinsic cryptic nature (i.e., small size, no dorsal fin, brief surface period, avoidance of boats), differentiating between the two species in situ has often been neglected and attempts have usually been met with skepticism. Moreover, a large area (Taiwan Strait and adjacent waters) exists where the two species are sympatric, which further complicates the task of species identification. In this study, we demonstrated that the two species can be differentiated at sea by direct observation and examination of photographs. By comparing photographs of living and dead specimens of both species, we describe useful diagnostic field characters for species identification of free-ranging finless porpoises. Differentiating these species through direct observation was possible but not trivial and the most confident and convincing identifications were those supported by quality images. © 2010 by Walter de Gruyter Berlin New York. Source


Wang J.Y.,FormosaCetus Research and Conservation Group | Wang J.Y.,Trent University | Yang S.C.,FormosaCetus Research and Conservation Group | Fruet P.F.,Grande Rio University | And 2 more authors.
Bulletin of Marine Science | Year: 2012

Accurate and precise estimates of abundance and survival rates are important for assessing the conservation status of cetacean populations. Mark-recapture analysis of photo-identification data of the critically endangered eastern Taiwan Strait (ETS) population of Indo-Pacific humpback dolphin, Sousa chinensis (Osbeck, 1765), was conducted on data collected between 2007 and 2010 to refine a preliminary, and the only available, abundance estimate for this isolated population (n = 99; CV = 51.6%), as well as to provide survival rates. About 14,000 good quality photographs (about 2100-6300 yr-1) were used to estimate both parameters for marked animals under Pollock's Robust Design model. The total population size (NT) was determined by correcting for the proportion of the population possessing long-lasting marks (Vi). The annual point estimates were lower, varying from 54 to 74, and had much better precision (CV varied from 4% to 13%) than previous estimates, suggesting that mark-recapture is a suitable method for estimating abundance of this population. Tese estimates also further supported the precarious state of the ETS population under another criterion of the IUCN Red List of Treatened Species. As expected for long-lived mammals, annual apparent survival rate was high at 0.985 (95% CI = 0.832-0.998). Continuing to monitor the ETS population of humpback dolphins with such high precision and accuracy will allow examination of the population's trends over time and to better understand its future persistence. © 2012 Rosenstiel School of Marine & Atmospheric Science of the University of Myami. Source


Ross P.S.,Canadian Department of Fisheries and Oceans | Barlow J.,Southwest Fisheries Science Center | Jefferson T.A.,Clymene Enterprises | Hickie B.E.,Trent University | And 11 more authors.
Marine Policy | Year: 2011

The adoption of endangered species laws in various nations has intensified efforts to better understand, and protect, at-risk species or populations, and their habitats. In many countries, delineating a portion of a species' habitat as particularly worthy of protection has become a mantra of these laws. Unfortunately, the laws themselves often provide scientists and managers with few, if any, guidelines for how to define such habitat. Conservationists and scientists may view protecting part of the habitat of an endangered species as an ineffectual compromise, while managers may be under pressure to allow a range of human activities within the species' habitat. In the case of small cetaceans, establishing boundaries for such areas can also be complicated by their mobility, the fluid nature of their environment, and the often ephemeral nature of their habitat features. The convergence of multiple human impacts in coastal waters around the world is impacting many small cetaceans (and other species) that rely on these areas for feeding, reproducing, and resting. The ten guiding principles presented here provide a means to characterize the habitat needs of small, at-risk cetaceans, and serve as a basis for the delineation of 'priority habitat' boundaries. This conceptual approach should facilitate a constructive discourse between scientists and managers engaged in efforts to recover endangered species. The degree to which the recovery of an at-risk species can be reconciled with sustainable economic activity will depend in part on how well these principles are incorporated into the delineation of priority habitat. © 2010. Source

Discover hidden collaborations