Application of a photo-identification based assessment model to southern right whales in South African waters

 

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dc.contributor.author Brandão, Anabela
dc.contributor.author Butterworth, Doug S
dc.contributor.author Müller, Andrea
dc.contributor.author Best, Peter B
dc.date.accessioned 2016-04-13T12:53:42Z
dc.date.available 2016-04-13T12:53:42Z
dc.date.issued 2012
dc.identifier.citation Brandão, A., Butterworth, D.S., Müller, A., & Best, P. B. (2012). Application of a photo-identification based assessment model to southern right whales in South African waters. MARAM: University of Cape Town. en_ZA
dc.identifier.uri http://hdl.handle.net/11427/18863
dc.description.abstract The three-mature-stages (receptive, calving and resting) model of Cooke et al. (2003) is applied to photo-identification data available from 1979 to 2010 for southern right whales in South African waters. The 2010 number of females having reached the age at first parturition is estimated to be 1 205, the total population (including males and calves) 4 725, and the annual population growth rate 6.8%. The probability (average 11%) that a resting mature whale rests for a further year appears to vary annually, whereas the probability (7%) that a receptive whale rest (or aborts) rather than calves the next year appears to be constant. Information from resightings of grey blazed calves as adults with calves allows estimation of first year survival rate of 0.914 (compared to a subsequent annual rate of 0.987, and an age at 50% maturity of 6.4 years. However this suggests also that 27% (s.e. 6%) of grey blazed calves lose their marking before becoming adults. In contrast, the relative proportions of grey blazed animals amongst calves and amongst calving adults suggest rather a value of 10% (s.e. 8%). If the proportion losing markings is in fact 10%, first year survival rates estimate drops to 0.837 and the population growth rate to 6.4% pa. en_ZA
dc.language eng en_ZA
dc.title Application of a photo-identification based assessment model to southern right whales in South African waters en_ZA
dc.type Working Paper en_ZA
dc.date.updated 2016-04-13T12:51:19Z
uct.type.publication Research en_ZA
uct.type.resource Research paper en_ZA
dc.publisher.institution University of Cape Town
dc.publisher.faculty Faculty of Science en_ZA
dc.publisher.department Marine Resource Assessment and Management Group en_ZA
uct.type.filetype Text
uct.type.filetype Image


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