An analysis of the small scale surveys of anchovy abundance around Robben and Dassen islands from 2009 to 2013
| dc.contributor.author | Robinson, William M L | |
| dc.contributor.author | Butterworth, Doug S | |
| dc.date.accessioned | 2016-03-22T09:20:29Z | |
| dc.date.available | 2016-03-22T09:20:29Z | |
| dc.date.issued | 2014 | |
| dc.date.updated | 2016-03-22T07:25:05Z | |
| dc.description.abstract | The results from the small scale hydroacoustic surveys of the abundance of anchovy around Robben and Dassen islands over the 2009-2013 period are analysed under the assumption of a Gaussian form for the trends in density at each island over the course of the winter months. Based primarily on AICc, the model selected from amongst a number of variants has the same trend in abundance with year for the two islands, compatible with the assumption used by Robinson (2013) in his GLM analysis of the impact of closures to pelagic fishing around these islands on penguin recovery, though the data have limited power to distinguish deviations from that assumption. The abundance estimates from the island surveys, though compatible also with the May recruitment survey trends, show appreciably larger variance. This raises the question of whether these small scale surveys merit continuation, unless it is possible to increase their frequency considerably during the winter months each year to improve the overall precision of the integrals over local abundance which they can provide. | en_ZA |
| dc.identifier.apacitation | Robinson, W. M. L., & Butterworth, D. S. (2014). <i>An analysis of the small scale surveys of anchovy abundance around Robben and Dassen islands from 2009 to 2013</i> University of Cape Town ,Faculty of Science ,Marine Resource Assessment and Management Group. Retrieved from http://hdl.handle.net/11427/18148 | en_ZA |
| dc.identifier.chicagocitation | Robinson, William M L, and Doug S Butterworth <i>An analysis of the small scale surveys of anchovy abundance around Robben and Dassen islands from 2009 to 2013.</i> University of Cape Town ,Faculty of Science ,Marine Resource Assessment and Management Group, 2014. http://hdl.handle.net/11427/18148 | en_ZA |
| dc.identifier.citation | Robinson, W.M.L & Butterworth, D.S. (2014). An analysis of the small scale surveys of anchovy abundance around Robben and Dassen islands from 2009 to 2013. FISHERIES. | en_ZA |
| dc.identifier.ris | TY - Working Paper AU - Robinson, William M L AU - Butterworth, Doug S AB - The results from the small scale hydroacoustic surveys of the abundance of anchovy around Robben and Dassen islands over the 2009-2013 period are analysed under the assumption of a Gaussian form for the trends in density at each island over the course of the winter months. Based primarily on AICc, the model selected from amongst a number of variants has the same trend in abundance with year for the two islands, compatible with the assumption used by Robinson (2013) in his GLM analysis of the impact of closures to pelagic fishing around these islands on penguin recovery, though the data have limited power to distinguish deviations from that assumption. The abundance estimates from the island surveys, though compatible also with the May recruitment survey trends, show appreciably larger variance. This raises the question of whether these small scale surveys merit continuation, unless it is possible to increase their frequency considerably during the winter months each year to improve the overall precision of the integrals over local abundance which they can provide. DA - 2014 DB - OpenUCT DP - University of Cape Town KW - survey KW - anchovy abundance KW - Robben Island KW - Dassen Island LK - https://open.uct.ac.za PB - University of Cape Town PY - 2014 T1 - An analysis of the small scale surveys of anchovy abundance around Robben and Dassen islands from 2009 to 2013 TI - An analysis of the small scale surveys of anchovy abundance around Robben and Dassen islands from 2009 to 2013 UR - http://hdl.handle.net/11427/18148 ER - | en_ZA |
| dc.identifier.uri | http://hdl.handle.net/11427/18148 | |
| dc.identifier.vancouvercitation | Robinson WML, Butterworth DS. An analysis of the small scale surveys of anchovy abundance around Robben and Dassen islands from 2009 to 2013. 2014 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/18148 | 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 | survey | en_ZA |
| dc.subject | anchovy abundance | en_ZA |
| dc.subject | Robben Island | en_ZA |
| dc.subject | Dassen Island | en_ZA |
| dc.title | An analysis of the small scale surveys of anchovy abundance around Robben and Dassen islands from 2009 to 2013 | en_ZA |
| dc.type | Working Paper | en_ZA |
| uct.type.filetype | Text | |
| uct.type.filetype | Image | |
| uct.type.publication | Research | en_ZA |
| uct.type.resource | Research paper | en_ZA |