Dmitrieva, L, Härkönen, T, Baimukanov, M et al. (8 more authors) (2015) Inter-year variation in pup production of Caspian seals (Pusa caspica) 2005-2012 determined from aerial surveys. Endangered Species Research, 28 (3). 209 - 223. ISSN 1863-5407
Abstract
Assessing species abundance and reproductive output is crucial for evaluations of population dynamics, conservation status and the development of management objectives. The Caspian seal (Pusa caspica) is a key predator in the Caspian Sea ecosystem and is listed as “Endangered” by IUCN. Here we report on fixed-wing aerial strip transect surveys of the breeding population on the Caspian Sea winter ice field carried out in February 2005-2012. Potential detection biases were estimated by applying a Petersen mark-recapture estimator to the counts from double photographic observations. We also tested for effects of weather conditions on count results, and for correlations between pup production and ice conditions and net primary productivity (npp). Fluctuations in pup production estimates were observed among years, ranging from 8,200 pups (95% CI 7,130-9342) in 2010 to 34,000 (95% CI 31,275-36,814) in 2005. Total adults on the ice ranged from 14,500 in 2010 to 66,300 in 2012. We did not detect significant associations between pup production and either ice summary data (ice season length, and ice area) or npp. The observed inter-year variation may be partly due to underlying biological drivers influencing the fecundity of the population, although measurement errors arising from observation bias, plus variation in survey timing and weather conditions may also have contributed. Identifying the potential drivers of Caspian seal population dynamics will require extending both the survey time series and the quality of supporting data. However, inter-year fluctuations should still cause concern that the population may be vulnerable to environmental variability and ecosystem dynamics.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © The authors 2015. Open Access under Creative Commons by Attribution Licence. Use, distribution and reproduction are un-restricted. Authors and original publication must be credited. |
Keywords: | Caspian Sea; Kazakhstan; Russian Federation; pinniped; marine mammals; abundance; strip survey; mark-recapture |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Biological Sciences (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 01 Jul 2015 12:35 |
Last Modified: | 23 Jun 2023 21:49 |
Published Version: | http://dx.doi.org/10.3354/esr00689 |
Status: | Published |
Publisher: | Inter Research |
Identification Number: | 10.3354/esr00689 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:87661 |