We are pleased to announce the following open access (freely available) publication in Frontiers in Marine Science, Marine Megafauna section:
Sex-specific patterns in abundance, temporary emigration and survival of Indo-Pacific bottlenose dolphins (Tursiops aduncus) in coastal and estuarine waters.
Sprogis, K.R., Pollock, K.H., Raudino, H.C., Allen, S.J., Kopps, A.M., Manlik, O., Tyne, J.A., and Bejder, L. (2016). Sex-specific patterns in abundance, temporary emigration and survival of Indo-Pacific bottlenose dolphins (Tursiops aduncus) in coastal and estuarine waters. Frontiers in Marine Science 3:12. doi: 10.3389/fmars.2016.00012.
Inherent difficulties in determining the sex of free-ranging, sexually monomorphic species often prevents a sex-specific focus on estimating abundance, movement patterns and survival rates. This study provides insights into sex-specific population parameters of Indo-Pacific bottlenose dolphins (Tursiops aduncus). Systematic, boat-based photo-identification surveys (n = 417) were conducted year-round from 2007-2013 in coastal and estuarine waters off Bunbury, Western Australia. Pollock’s Robust Design was used to quantify population parameters for three datasets: i) adults and juveniles combined, ii) adult females and iii) adult males. For all datasets, abundance estimates varied seasonally, with general highs during summer and/or autumn, and lows during winter. Dolphins had seasonally structured temporary emigration rates with similar trends between sexes. The derived return rate (1-γ’) of temporary emigrants into the study area was highest from winter to spring, indicating that dolphins had a high probability of return into the study area during spring. We suggest that the return of dolphins into the study area and increase in abundance is influenced by the breeding season (summer/autumn). Prey availability is likely a main driver responsible for the movement of dolphins out of the study area during winter. Seasonal apparent survival rates were constant and high (0.98-0.99) for all datasets. High apparent survival rates suggest there is no permanent emigration from the study area. Our sex-specific modeling approach offers a comprehensive interpretation of the population dynamics of a top predator in a coastal and estuarine environment and acts as a model for future sex-based population studies on sexually monomorphic species.
This article is a product of Dr Kate Sprogis’s PhD thesis, entitled: “Sex-specific patterns in abundance, home ranges and habitat use of Indo-Pacific bottlenose dolphins (Tursiops aduncus) in south-western Australia”, which can be accessed here.
Elements of this study were also presented in San Francisco at the 21st Biennial Conference on the Biology of Marine Mammals in December 2015 as a poster entitled “The effect of the El Niño Southern Oscillation on dolphin abundance and movements“.
Kate’s PhD was undertaken through the South West Marine Research Program in Bunbury, Western Australia.
Download the paper:
The article is freely available from Frontiers in Marine Science, or alternatively, if you are unable to download the article please email the lead author, Kate Sprogis, for a pdf at k.sprogis at murdoch.edu.au, or request a copy through Research Gate.
Our publications made possible through the South West Marine Research Program:
McCluskey, S.M., Bejder, L., and Loneragan, N.R. (2016). Assessing potential dolphin prey availability and calorific value in an estuarine and coastal environment. Frontiers in Marine Science.
Sprogis, K.R., Raudino, H.C., Rankin, R., MacLeod, C.D., and Bejder, L. (2016). Home range size of adult Indo-Pacific bottlenose dolphins (Tursiops aduncus) in a coastal and estuarine system is habitat and sex-specific. Marine Mammal Science 32, 287-308. doi: 10.1111/mms.12260.
Smith, H., Frère, C., Kobryn, H., and Bejder, L. (2016). Dolphin sociality, distribution and calving as important behavioural patterns informing management. Animal Conservation. doi: 10.1111/acv.12263.
H.C., Pollock, K., Waples, K., Bradley, S., and Bejder, L. (2013). Use of the robust design to estimate seasonal abundance and demographic parameters of a coastal bottlenose dolphin (Tursiops aduncus) population. PLoS ONE 8, e76574. doi: 10.1371/journal.pone.0076574.
We thank numerous volunteers and research assistants who helped with fieldwork and data processing. Thank you to our research associates for collecting field data and/or data management; M. Cannon, D. Chabanne, V. Buchanan, K. Nicholson and B. Goguelat. We are grateful to M. Krützen, D. McElligott and A. Sellas, who obtained some of the biopsies for genetic analyses. We thank C. Daniel for sexing results from molecular analyses. We are grateful to R. Wells, G. Parra, R. Constantine, B. Würsig, K. Nicholson and A. Friedlaender and G.Schofield, whose comments greatly improved this manuscript.
We thank the funding partners for financial support from the South West Marine Research Program; Bemax Cable Sands, BHP Billiton Worsley Alumina Ltd, the Bunbury Dolphin Discovery Centre, Bunbury Port Authority, City of Bunbury, Cristal Mining, the Western Australian Department of Parks and Wildlife, Iluka, Millard Marine, Naturaliste Charters, Newmont Boddington Gold, South West Development Commission and WA Plantation Resources. KRS was supported throughout her PhD by an Australian Postgraduate Award, Murdoch University Research Excellence scholarship and a SWMRP Scholarship.