[MARMAM] New publication: Use of the Robust Design to estimate abundance and demographic parameters for a coastal bottlenose dolphin (Tursiops aduncus) population

Lars Bejder L.Bejder at murdoch.edu.au
Mon Oct 14 19:10:59 PDT 2013

Dear MARMAM readers,

We are pleased to announce a recent publication in PLoS ONE entitled:

Title: Use of the Robust Design to estimate abundance and demographic parameters for a coastal bottlenose dolphin (Tursiops aduncus) population
Authors: Smith, H.C., Pollock, K., Waples, K., Bradley, S. and Bejder, L.

As delphinid populations become increasingly exposed to human activities we rely on our capacity to produce accurate abundance estimates upon which to base management decisions. This study applied mark-recapture methods following the Robust Design to estimate abundance, demographic parameters, and temporary emigration rates of an Indo-Pacific bottlenose dolphin (Tursiops aduncus) population off Bunbury, Western Australia. Boat-based photo-identification surveys were conducted year-round over three consecutive years along pre-determined transect lines to create a consistent sampling effort throughout the study period and area. The best fitting capture-recapture model showed a population with a seasonal Markovian temporary emigration with time varying survival and capture probabilities. Abundance estimates were seasonally dependent with consistently lower numbers obtained during winter and higher during summer and autumn across the three-year study period. Specifically, abundance estimates for all adults and juveniles (combined) varied from a low of 63 (95% CI 59 to 73) in winter of 2007 to a high of 139 (95% CI 134 to148) in autumn of 2009. Temporary emigration rates (γ') for animals absent in the previous period ranged from 0.34 to 0.97 (mean = 0.54; ±SE 0.11) with a peak during spring. Temporary emigration rates for animals present during the previous period (γ'') were lower, ranging from 0.00 to 0.29, with a mean of 0.16 (± SE 0.04). This model yielded a mean apparent survival estimate for juveniles and adults (combined) of 0.95 (± SE 0.02) and a capture probability from 0.07 to 0.51 with a mean of 0.30 (± SE 0.04). This study demonstrates the importance of incorporating temporary emigration to accurately estimate abundance of coastal delphinids. Temporary emigration rates were high in this study, despite the large area surveyed, indicating the challenges of sampling highly mobile animals which range over large spatial areas.

Full citation details: Smith HC, Pollock K, Waples K, Bradley S, 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(10): e76574. doi:10.1371/journal.pone.0076574.

The paper is freely downloadable from PLoS ONE: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0076574;jsessionid=A60164419B7B03CB6ABA05CC3C9A1B3C

**Please note:  Unfortunately, the journal has duplicated Figure 1 in the compiled PDF version and therefore Figure 2 is missing in the PDF. However, the online HTML version of Figure 2 is correct. We are hoping the journal will rectify this soon.

If you have any questions, please contact Holly Raudino (h.smith at murdoch.edu.au<mailto:h.smith at murdoch.edu.au>) or Lars Bejder (l.bejder at murdoch.edu.au<mailto:l.bejder at murdoch.edu.au>).

Kind regards,

Lars Bejder
Head, Cetacean Research Unit
School of Veterinary and Life Sciences
Murdoch University South Street  Murdoch WA 6150
Website: www.mucru.org<http://www.cffr.murdoch.edu.au/mucru/lars_bejder.html>

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