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Browsing by Author "De Moor, Carryn L"

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Comparisons of alternative single-area sardine TAC Management procedures

Author: De Moor, Carryn L Date: 2013 The Small Pelagic Scientific Working Group has requested further testing of Candidate Management Procedures allocating a single-area sardine Total Allowable Catch (TAC) for possible update of Interim OMP-13 v2 for use in setting the 2014 ... Read more
Did high directed sardine TACs cause the rapid decline in sardine abundance

Author: De Moor, Carryn L ; Butterworth, Doug S Date: 2009 A question that has been raised is whether the rapid decline in the sardine abundance after 2002 can be attributed either in part or in full to the relatively large sardine catches in the early part of this decade. One way to consider this ... Read more
Exploring options for spatially disaggregated directed sardine catch under OMP-14

Author: De Moor, Carryn L ; Butterworth, Doug S Date: 2014 At the March 2014 Small Pelagic Scientific Working Group (SPSWG) meeting it was agreed that the most appropriate way-forward in terms of management of the sardine and anchovy pelagic fishery would be to finalise an Operational Management ... Read more
An extension to the simple implementation of the "River Model" to estimate the impact of fishing on the amount of anchovy available to West Coast penguin colonies which takes account of within season variability in recruitment

Author: Butterworth, Doug S ; De Moor, Carryn L Date: 2010 The assumption of an earlier analysis of a constant flow of anchovy recruits along the West Coast during the winter months is replaced by introducing variability at a monthly scale. The extent of this variability is based on the monthly ... Read more
Extrapolation of recruit numbers to Cape Infanta in the years for which the survey only reached Cape Agulhas

Author: De Moor, Carryn L ; Butterworth, Doug S Date: 2011 The time series of sardine and anchovy recruits used in assessments and to set the final anchovy TAC and sardine TAB in June each year are based on the surveyed area west of Cape Infanta. In some years, the survey did not cover the full area ... Read more
A final record of the generation of data used in the 2011 sardine and anchovy assessments

Author: De Moor, Carryn L ; Coetzee, J ; Durholtz, D ; Merkle, D ; van der Westhuizen, J J Date: 2011 The data to which the South African anchovy and sardine assessments are tuned are not raw data. Some of the data have already been subjected to a number of analyses and refinements. These associated calculations are often done “behind the ... Read more
Finalised Assessment of the South African anchovy resource using data from 1984 – 2011: results at the posterior mode

Author: De Moor, Carryn L ; Butterworth, Doug S Date: 2012 The operating model (OM) for the South African anchovy resource has been updated from that used to develop OMP-08 given five more years of data, a revised time series of commercial catch and November survey proportion-at-age 1 estimates ... Read more
Further OMP-14 Performance Statistics

Author: De Moor, Carryn L Date: 2015 de Moor and Butterworth (2014) detailed OMP-14, and provided many of the performance statistics relating to the objectives that were agreed for use during OMP-14 development (de Moor and Coetzee 2012). This document provides the remaining ... Read more
Further results from future projections of a single or two sardine stock operating model, with initial results using a two-area directed sardine TAC

Author: De Moor, Carryn L ; Butterworth, Doug S ; Robinson, William M L Date: 2013 de Moor and Butterworth (2013a) showed some initial projections for future average directed catch and risk to the resources, assuming a no catch scenario, Interim OMP-13 v2, or a similar Management Procedure (MP) with re-tuned control parameters. ... Read more
Further results towards the selection of "Draft OMP-13"

Author: De Moor, Carryn L ; Butterworth, Doug S Date: 2012 de Moor and Butterworth (2012a) presented results for a “Base MP” variant which contained mostly the same constraint parameters as OMP-08, except for a lower maximum total anchovy TAC. That “Base MP” variant was tuned to risk levels ( < 21.0 ... Read more
Further results using Interim OMP-13v2

Author: De Moor, Carryn L Date: 2013 Interim OMP-13v2 (de Moor and Butterworth 2013) was recently adopted by the Small Pelagic Scientific Working Group to finalise the anchovy TAC and small sardine TAB with anchovy for 2013. Further work on this OMP towards adopting a final ... Read more
Further testing of “top-up” rules for the directed sardine TAC in OMP-14

Author: De Moor, Carryn L Date: 2014 The next Operational Management Procedure (OMP) under development for the South African sardine and anchovy fishery, OMP-14, allows for a conservative lower initial directed sardine TAC for the range of November hydroacoustic survey estimates ... Read more
Further work towards the assessment of the South African round herring (Etrumeus whiteheadi) resource using data from 1987 to 2010

Author: De Moor, Carryn L ; Butterworth, Doug S Date: 2010 Round herring (Etrumeus whiteheadi), commonly referred to as Red Eye, is exploited by the South African pelagic fishery. The fishery has been managed with a Precautionary Upper Catch Limit of 100 000t for at least the past eight years. An ... Read more
How should the sardine length frequencies be weighted?

Author: De Moor, Carryn L ; Butterworth, Doug S Date: 2009 Length frequencies are calculated for the annual sardine November surveys using samples from trawls undertaken during the spawner biomass acoustic surveys and using a method of calculation that was developed by Roel and probably also Hampton ... Read more
How should the sardine length frequencies be weighted? Exploring alternative methods

Author: De Moor, Carryn L ; Butterworth, Doug S Date: 2009 The effect of alternative methods of weighting trawls when estimating the proportions-at-length in November surveys is examined. The current method used, in which the length frequencies from the individual trawls are weighted by the acoustic ... Read more
Initial assessment of the South African round herring (Etrumeus whiteheadi) resource using data from 1988 to 2010

Author: De Moor, Carryn L ; Butterworth, Doug S Date: 2010 An initial assessment of the South African Round Herring (Etrumeus whiteheadi) resource, commonly referred to as Red Eye, has been undertaken. Considering the proportion of females in different reproductive stages, Roel and Melo (1990) report ... Read more
Initial exploration of available data to estimate sardine recruitment on the south coast

Author: De Moor, Carryn L ; Coetzee, J C ; Butterworth, Doug S Date: 2014 Annual May/June survey estimates of sardine recruitment east of Cape Infanta are low in comparison to those west of Cape Infanta and in comparison to the numbers of recruits needed to result in the recent peak in 1+ biomass on the south coast. ... Read more
Interim OMP-13

Author: De Moor, Carryn L ; Butterworth, Doug S Date: 2012 The management procedure used to recommend total allowable catches (TACs) and bycatches (TABs) for sardine and anchovy in South African waters is currently being revised. Given the extensive testing desired for this new management procedure, ... Read more
Interim OMP-13 v2

Author: De Moor, Carryn L ; Butterworth, Doug S Date: 2013 The management procedure used to recommend total allowable catches (TACs) and bycatches (TABs) for sardine and anchovy in South African waters is currently being revised. Given the extensive testing desired for this new management procedure, ... Read more
Is the management procedure approach equipped to handle short-lived pelagic species with their boom and bust dynamics? The case of the South African fishery for sardine and anchovy

Author: De Moor, Carryn L ; Butterworth, Doug S ; De Oliveira, J A A Date: 2011 Worldwide, small shoaling pelagic fish manifest rapid and substantial natural changes in abundance. Is the application of a management procedure (MP), evaluated using simulation tests [i.e. a MP approach otherwise known as management strategy ... Read more

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