Abalone spatial- and age-structured assessment model results for Zones A, B, C and D in 2005
| dc.contributor.author | Plagányi, Éva E | |
| dc.contributor.author | Butterworth, Doug S | |
| dc.date.accessioned | 2016-03-30T10:14:04Z | |
| dc.date.available | 2016-03-30T10:14:04Z | |
| dc.date.issued | 2005 | |
| dc.date.updated | 2016-03-30T10:11:57Z | |
| dc.description.abstract | A summary is presented of the results obtained from the 2005 Reference-case model that was fit to Zones A, B, CNP, CP and D in combination (hereafter referred to as the “combined ABCD model”). The full details of the spatial- and age-structured production model (ASPM) are provided in Appendix 1. Model results estimate a pristine spawning biomass, Bsp 0 (in tonnes), of 11930, 6190, 6890 and 7900 for Zones A, B, C and D respectively. The current spawning biomasses of abalone in Zones A, B and D are estimated at ca. 38 %, 40 % and 28 % respectively of their preexploitation levels. The “nonpoached” CNP and “poached” CP areas of Zone C are estimated at ca. 23 % and 10 % respectively with the inshore region particularly depleted: the model predicts zero remaining abalone in the inshore CP area. Natural mortality is reasonably estimated and in Zones C and D, the additional mortality estimated for 0-yr old abalone (due to the ecosystem-change effect) corresponds to near zero current annual survival rates. Poaching is severely impacting the resource, with Zone A particularly impacted in recent years. The combined Zones A-D model-predicted 2005 poaching estimate of 1150 MT (corresponding to the assumption that, on average, 19% of all poached abalone are confiscated) is more than six times the legal 2005 commercial TAC for these zones. | en_ZA |
| dc.identifier.apacitation | Plagányi, É. E., & Butterworth, D. (2005). <i>Abalone spatial- and age-structured assessment model results for Zones A, B, C and D in 2005</i> University of Cape Town ,Faculty of Science ,Marine Resource Assessment and Management Group. Retrieved from http://hdl.handle.net/11427/18395 | en_ZA |
| dc.identifier.chicagocitation | Plagányi, Éva E, and Doug Butterworth <i>Abalone spatial- and age-structured assessment model results for Zones A, B, C and D in 2005.</i> University of Cape Town ,Faculty of Science ,Marine Resource Assessment and Management Group, 2005. http://hdl.handle.net/11427/18395 | en_ZA |
| dc.identifier.citation | Plagányi, É., & Butterworth, D. (2005). Abalone spatial-and age-structured assessment model results for Zones A, B, C and D in 2005. | en_ZA |
| dc.identifier.ris | TY - Working Paper AU - Plagányi, Éva E AU - Butterworth, Doug AB - A summary is presented of the results obtained from the 2005 Reference-case model that was fit to Zones A, B, CNP, CP and D in combination (hereafter referred to as the “combined ABCD model”). The full details of the spatial- and age-structured production model (ASPM) are provided in Appendix 1. Model results estimate a pristine spawning biomass, Bsp 0 (in tonnes), of 11930, 6190, 6890 and 7900 for Zones A, B, C and D respectively. The current spawning biomasses of abalone in Zones A, B and D are estimated at ca. 38 %, 40 % and 28 % respectively of their preexploitation levels. The “nonpoached” CNP and “poached” CP areas of Zone C are estimated at ca. 23 % and 10 % respectively with the inshore region particularly depleted: the model predicts zero remaining abalone in the inshore CP area. Natural mortality is reasonably estimated and in Zones C and D, the additional mortality estimated for 0-yr old abalone (due to the ecosystem-change effect) corresponds to near zero current annual survival rates. Poaching is severely impacting the resource, with Zone A particularly impacted in recent years. The combined Zones A-D model-predicted 2005 poaching estimate of 1150 MT (corresponding to the assumption that, on average, 19% of all poached abalone are confiscated) is more than six times the legal 2005 commercial TAC for these zones. DA - 2005 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2005 T1 - Abalone spatial- and age-structured assessment model results for Zones A, B, C and D in 2005 TI - Abalone spatial- and age-structured assessment model results for Zones A, B, C and D in 2005 UR - http://hdl.handle.net/11427/18395 ER - | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/11427/18395 | |
| dc.identifier.vancouvercitation | Plagányi ÉE, Butterworth D. Abalone spatial- and age-structured assessment model results for Zones A, B, C and D in 2005. 2005 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/18395 | 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.subject.other | Abalone | |
| dc.title | Abalone spatial- and age-structured assessment model results for Zones A, B, C and D in 2005 | 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 |