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Browsing by Author "Johnston, S J"

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The 2017 Horse Mackerel Updated Assessment

Author: Johnston, S J ; Butterworth, D S Date: Sep 2017 FISHERIES/2016/SEP/SWG-DM/51 provided a full description of the current stock assessment model for the South African Horse Mackerel. FISHERIES/2016/SEP/SWG-DM/52 reported updated 2016 assessments for a number of model variants where the ... Read more
2017 updated South Coast Rock Lobster assessment results

Author: Johnston, S J ; Butterworth, D S Date: Aug 2017 The 2017 assessment of the resource is updated given two further years of data now available. Recruitment is estimated to have increased over the last two seasons compared to the previous three seasons when recruitment was estimated to be ... Read more c b
Initial OMP candidates for the Nightingale rock lobster fishery

Author: Johnston, S J ; Butterworth, D S Date: Jul 2017 The performances of a number of OMP candidates are reported here. Simulation results do not vary much amongst the various candidates. For this and other reasons it is recommended that at this stage CMP3 be adopted as the new OMP. This CMP has ... Read more
Inshore versus offshore split of available quota

Author: Johnston, S J ; Butterworth, D S Date: Jan 2017 Although each of the five super-areas used in the management of the West Coast rock lobster fishery is treated as homogenous in assessments, it is clear that there are inshore areas where predominantly hoops and bakkies are deployed, and ... Read more
RECOMMENDATIONS ON ROCK LOBSTER TACs FOR THE TRISTAN GROUP OF ISLANDS FOR THE 2017/18 SEASON

Author: Butterworth, D S ; Johnston, S J Date: Aug 2017 OMPs have recently been accepted as the basis to recommend TACs for Tristan, Inaccessible and Gough islands. Given that for Inaccessible and Gough the recent catch rates continue to be above the associated OMP’s target catch rate, the OMPs ... Read more
Updated (and rescaled) Tristan GLM-standardised lobster CPUE to take account of data for the 2016 season

Author: Johnston, S J ; Butterworth, D S Date: May 2017 The Powerboat CPUE series for Tristan was last updated in 2016 (MARAM/Tristan/2016/MAY/08) and took data for the 1994-20141 seasons into account. This GLM incorporated a method whereby the full GLM for Tristan can be rescaled to take into ... Read more
Updated 2017 GLMM-standardised lobster CPUE from the Tristan da Cunha outer group of islands

Author: Johnston, S J ; Brandão, A ; Butterworth, D S Date: May 2017 The longline CPUE series for Inaccessible and Gough islands are GLMM standardised through to 20161. For Nightingale, the fishery was closed for the 2011 season and catches were set at precautionary levels for the 2011 and 2012 seasons. The ... Read more
Updated 2017 Nightingale island rock lobster assessment

Author: Johnston, S J ; Butterworth, D S Date: May 2017 This paper provides a further updated assessment of the rock lobster resource at Nightingale island. This assessment includes updated data from both the commercial fishery and the biomass surveys. The recent (2013-2016) high GLM standardised ... Read more
Using decision analysis to evaluate candidate OMPs for the South African west coast rock lobster fishery

Author: Moloney, C L ; Johnston, S J Date: 2002 Simulation models frequently are used to provide information to assist in decision-making in natural resource management. The sheer volume of information to process can be overwhelming, however, and there is a danger that some management ... Read more
West coast rock lobster projections to 2021 under the current TAC 2016 levels

Author: Johnston, S J ; Butterworth, D S Date: Jan 2017 The SWG TAC recommendations for the next five years corresponded to reducing the previous recovery target by 2021 compared to 2006 from a 35% increase down to about a 7% decrease in median terms. The final DAFF decision was to leave the TAC ... Read more