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Browsing by Author "Coetzee, J C"

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A summary of the South African sardine (and anchovy) fishery. MARAM/IWS/2019/Sardine/BG1

Author: Coetzee, J C ; de Moor, C L ; Butterworth, Doug S Date: 2019 The sardine fishery is an important component of the South African purse-seine fishery, the largest commercial fishery in South Africa (by landed mass). This fishery, initially established on the West Coast, but with some subsequent infrastructure ... Read more
Abrupt environmental shift associated with changes in the distribution of Cape anchovy Engraulis encrasicolus spawners in the southern Benguela

Author: Roy, C ; van der Lingen, C D ; Coetzee, J C ; Lutjeharms, J R E Date: 2007 Cape anchovy Engraulis encrasicolus spawners in the southern Benguela showed an eastward shift in their distribution on the Agulhas Bank that occurred abruptly in 1996 and has since persisted. We assessed whether this shift was environmentally ... Read more
Alternative hypotheses of two mixing stocks of South African sardine: initial testing

Author: de Moor, Carryn L ; Butterworth, Doug S ; van der Lingen, C D ; Coetzee, J C Date: 2014 A new assessment of sardine based on data from 1984 to 2014 is planned to commence in a few months’ time. This assessment will eventually form the operating model which will be used to project the sardine population forward in time under ... Read more
Can anchovy age structure be estimated from length distribution data collected during surveys?

Author: De Moor, Carryn L ; Butterworth, Doug S ; Coetzee, J C Date: 2013 Historically, a time-series of proportions-at-age 1 from annual November hydro-acoustic surveys has been used to inform the assessment of, and in particular the choice of appropriate values for juvenile and adult natural mortality for, the ... Read more
Comparative harvest rates for sardine and anchovy stocks elsewhere

Author: Butterworth, Doug S ; Coetzee, J C Date: Aug 2016 A risk analyses conducted by de Moor and Butterworth (2016a) in which they consider the risk to the sardine resource in terms of harvest proportion has prompted discussion about acceptable harvest proportions elsewhere for other small pelagic ... Read more c b
Discussion of OMP-17 simulation projection framework in respect of sardine

Author: de Moor, C L ; Butterworth, Doug S ; Coetzee, J C Date: Sep 2016 The simulation projection framework to be used to test Candidate Management Procedures for OMP-17 is yet to be developed (cf de Moor and Butterworth (2013a) for the framework used when developing OMP-14). However, given experience gained ... Read more
Further information provided by the Small Pelagic Working Group in respect of the IFFO FISHERY ASSESSMENT REPORT of anchovy and redeye round herring

Author: Coetzee, J C ; Butterworth, Doug S Date: 2012 “The South African management regime from the evidence assessed is robust and provides a solid framework for the management for the pelagic species within this fishery. The scientific evaluations of this stock and associated by catch stock ... 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
Refined estimates of South African pelagic fish biomass from hydro-acoustic surveys: quantifying the effects of target strength, signal attenuation and receiver saturation

Author: Coetzee, J C ; Merkle, D ; de Moor, C L ; Twatwa, N M ; Barange, M ; Butterworth, Doug S Date: 2008 The biomass of small pelagic fish species off the coast of South Africa has been monitored since 1984 using hydro-acoustic survey techniques. These time-series of spawner biomass and recruitment estimates form the basis for management of both ... Read more
Refined estimates of South African pelagic fish biomass from hydro-acoustic surveys:quantifying the effects of target strength, signal attenuation and receiver saturation

Author: Coetzee, J C ; Merkle, D ; De Moor, Carryn L ; Twatwa, N M ; Barange, M ; Butterworth, Doug S Date: 2008 The biomass of small pelagic fish species off the coast of South Africa has been monitored since 1984 using hydro-acoustic survey techniques. These time-series of spawner biomass and recruitment estimates form the basis for management of both ... Read more
Revised estimates of abundance of South African sardine and anchovy from acoustic surveys adjusting for echosounder saturation in earlier surveys and attenuation effects for sardine

Author: De Moor, Carryn L ; Butterworth, Doug S ; Coetzee, J C Date: 2008 Hydro-acoustic surveys have been used to provide annual estimates of May recruitment and November spawner biomass of the South African sardine Sardinops sagax and anchovy Engraulis encrasicolus resources since 1984. These time-series of ... Read more