Capture-recapture analyses of humpback population sizes and increase rates: breeding stocks C1-C3
| dc.contributor.author | Johnston, Susan J | |
| dc.contributor.author | Butterworth, Doug S | |
| dc.date.accessioned | 2016-04-11T09:10:05Z | |
| dc.date.available | 2016-04-11T09:10:05Z | |
| dc.date.issued | 2008 | |
| dc.date.updated | 2016-04-11T09:09:08Z | |
| dc.description.abstract | Both maximum likelihood and Bayesian methodologies are developed to analyse the photo-ID and genotypic capture-recapture data available for the C1 and C3 breeding sub-stocks of humpback whales in the western Indian Ocean. A simple exponential growth population model is assumed, and estimates of annual growth rate and abundances determined. Maximum likelihood estimates of r are generally imprecise and often the point estimates are demographically infeasible. The most reliable results are probably those from the Bayesian analyses with a prior for r of U[0; 0.106]. The data update this prior somewhat more for C3 than for C1, with a median posterior estimate of 8.0% for the former. Posterior median estimates of abundance for each sub-stock when analysed in isolation are both a little more than 6500. An interchange model is developed to take account of photo-ID information on exchanges between the C1 and C3 regions (only one such exchange has been recorded thus far). The results show little difference between the combined abundances estimated for the two sub-stocks with such interchange, compared to the sum of results for the two analysed in isolation; the posterior median annual probability of an animal from either sub-stock visiting the other’s region in any one year is a little more than 5%, with an upper 5%-ile of some 19%. It should be understood that the results presented are intended to be illustrative, not definitive, having the purpose of facilitating further runs and refinements of the models during Scientific Committee discussions. | en_ZA |
| dc.identifier.apacitation | Johnston, S. J., & Butterworth, D. S. (2008). <i>Capture-recapture analyses of humpback population sizes and increase rates: breeding stocks C1-C3</i> University of Cape Town ,Faculty of Science ,Marine Resource Assessment and Management Group. Retrieved from http://hdl.handle.net/11427/18738 | en_ZA |
| dc.identifier.chicagocitation | Johnston, Susan J, and Doug S Butterworth <i>Capture-recapture analyses of humpback population sizes and increase rates: breeding stocks C1-C3.</i> University of Cape Town ,Faculty of Science ,Marine Resource Assessment and Management Group, 2008. http://hdl.handle.net/11427/18738 | en_ZA |
| dc.identifier.citation | Johnston, S. J., & Butterworth, D. S. (2008). Capture-recapture analyses of humpback population sizes and increase rates: Breeding stocks C1-C3. Paper SC/60/SH37rev presented to the IWC Scientific Committee, May 2008 (unpublished). 27pp.[Available from the office of this Journal]. | en_ZA |
| dc.identifier.ris | TY - Working Paper AU - Johnston, Susan J AU - Butterworth, Doug S AB - Both maximum likelihood and Bayesian methodologies are developed to analyse the photo-ID and genotypic capture-recapture data available for the C1 and C3 breeding sub-stocks of humpback whales in the western Indian Ocean. A simple exponential growth population model is assumed, and estimates of annual growth rate and abundances determined. Maximum likelihood estimates of r are generally imprecise and often the point estimates are demographically infeasible. The most reliable results are probably those from the Bayesian analyses with a prior for r of U[0; 0.106]. The data update this prior somewhat more for C3 than for C1, with a median posterior estimate of 8.0% for the former. Posterior median estimates of abundance for each sub-stock when analysed in isolation are both a little more than 6500. An interchange model is developed to take account of photo-ID information on exchanges between the C1 and C3 regions (only one such exchange has been recorded thus far). The results show little difference between the combined abundances estimated for the two sub-stocks with such interchange, compared to the sum of results for the two analysed in isolation; the posterior median annual probability of an animal from either sub-stock visiting the other’s region in any one year is a little more than 5%, with an upper 5%-ile of some 19%. It should be understood that the results presented are intended to be illustrative, not definitive, having the purpose of facilitating further runs and refinements of the models during Scientific Committee discussions. DA - 2008 DB - OpenUCT DP - University of Cape Town J1 - International Whaling Commission LK - https://open.uct.ac.za PB - University of Cape Town PY - 2008 T1 - Capture-recapture analyses of humpback population sizes and increase rates: breeding stocks C1-C3 TI - Capture-recapture analyses of humpback population sizes and increase rates: breeding stocks C1-C3 UR - http://hdl.handle.net/11427/18738 ER - | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/11427/18738 | |
| dc.identifier.vancouvercitation | Johnston SJ, Butterworth DS. Capture-recapture analyses of humpback population sizes and increase rates: breeding stocks C1-C3. 2008 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/18738 | en_ZA |
| dc.language | eng | en_ZA |
| dc.publisher.department | Marine Resource Assessment and Management Group | en_ZA |
| dc.publisher.faculty | Faculty of Science | en_ZA |
| dc.publisher.institution | University of Cape Town | |
| dc.source | International Whaling Commission | |
| dc.source.uri | https://iwc.int/home | |
| dc.subject.other | humpback whales | |
| dc.subject.other | breeding stocks | |
| dc.title | Capture-recapture analyses of humpback population sizes and increase rates: breeding stocks C1-C3 | en_ZA |
| dc.type | Working Paper | en_ZA |
| uct.type.filetype | Text | |
| uct.type.publication | Research | en_ZA |
| uct.type.resource | Research paper | en_ZA |