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A Bayesian assessment of breeding stocks B, C and G of Southern Hemisphere humpback whales using a prior for growth rate from analyses for stocks D and E

Author: Johnston, Susan J ; Butterworth, Doug S Date: 2005 Bayesian assessment of breeding stocks B, C and G of the Southern Hemisphere humpback whales are presented. These assessments incorporate a prior for the maximum growth rate r derived from similar assessments for breeding stocks D and E. This ... Read more
A Bayesian assessment of the west and east Australian breeding populations (stocks D and E) of Southern Hemisphere humpback whales

Author: Johnston, Susan J ; Butterworth, Doug S Date: 2005 A Bayesian assessment of breeding stocks D and E shows qualitatively similar results to those presented previously using maximum likelihood methodology, although (in posterior median terms) breeding stock D is indicated to be a little less ... Read more
Bayesian assessments of Southern Hemisphere humpback whale breeding Sub-stocks C1 and C3, including allowance for interchange on the breeding grounds

Author: Johnston, Susan J ; Butterworth, Doug S Date: 2008 Bayesian stock assessment results for breeding sub-stocks C1 and C3 using models which allow for interchange on the breeding grounds as well as mixing on the feeding grounds are illustrated for two models – the sabbatical model and the resident ... Read more
Bayesian assessments of the southern hemisphere humpback whale breeding stock B using three different models for stock-structure

Author: Müller, Andrea ; Butterworth, Doug S ; Johnston, Susan J Date: 2010 Three different models are considered for Southern Hemisphere humpback breeding stock B: Model 1, a single fully-mixed stock; Model 2, reproductively independent stocks B1 off Gabon and B2 of the southern African coastline; and Model 3 with ... Read more
Bayesian assessments using models which allow for interchange on the breeding grounds of Southern Hemisphere humpback whale breeding Sub stocks C1 and C3

Author: Johnston, Susan J ; Butterworth, Doug S Date: 2009 Bayesian stock assessment results for breeding sub-stocks C1 and C3 using models which allow for interchange on the breeding grounds as well as mixing on the feeding grounds are illustrated for four models – the sabbatical, tourist and migrant ... Read more
Biological issues relating to projections of the West Coast rock lobster resource into the future for OMP trials

Author: Johnston, Susan J ; Butterworth, Doug S Date: 2011 The assessment models which form the “operating models” upon which alternate OMP candidates are tested are currently being updated for application in developing OMP 2011 (see Johnston and Butterworth 2011). Read more
Capture-recapture analyses of humpback population sizes and increase rates: breeding stocks C1-C3

Author: Johnston, Susan J ; Butterworth, Doug S Date: 2008 Both maximum likelihood and Bayesian methodologies are developed to analyse the photo-ID and genotypic capture-recapture data available for the C1 and C3 breeding sub-stocks of humpback whales in the western Indian Ocean. A simple exponential ... Read more
Capture-recapture analyses of humpback whale population sizes and increase rates: breeding sub-stock B1

Author: Johnston, Susan J ; Butterworth, Doug S Date: 2008 Maximum likelihood and Bayesian approaches are applied to estimate parameters of a simple experimental growth model for the humpback whales of breeding sub-stock B1 from photo-ID and genotypic capture-recapture data for all observation sites ... Read more
The catch and effort data to be used in GLM analyses to produce CPUE indices for the four islands of the Tristan da Cunha group

Author: Johnston, Susan J ; de Decker, M Date: 2009 The Tristan da Cunha group of islands consist of the main island of Tristan da Cunha, and three outer islands – Gough, Nightingale and Inaccessible. Fishing at the outer islands uses two methods – longlining and powerboats – although longlining ... Read more c b
Corrected assessment results for Southern Hemisphere humpback whales from breeding stocks D and G

Author: Johnston, Susan J ; Butterworth, Doug S Date: 2007 Corrected Bayesian stock assessment results for breeding stocks D and G which take into account trend information from the IDCR/SOWER survey results are presented. At the 2006 IWC scientific meeting, the authors presented various stock ... Read more
Creating catch length frequencies for the Tristan group of islands using factory pack category data

Author: Johnston, Susan J Date: 2010 Reliable factory processing records of lobsters caught at all four islands of the Tristan group are available since 2001. These “pack category” data record the number of lobsters that fall into different packing categories. There are two types ... Read more c b
Current and past OMPs for West Coast Rock Lobster – what are appropriate management targets?

Author: Johnston, Susan J ; Butterworth, Doug S Date: 2010 This document provides a short review of past OMPs that have been developed to set annual TACs for the west coast rock lobster fishery. A new OMP will shortly be developed for the fishery which will be used to set TACs (and their spatial/user-group ... Read more
Data and model assumptions for an age structured production model of the Tristan lobster fishery

Author: Johnston, Susan J Date: 2010 An age-structured production model (ASPM) is to be developed for each of the four islands of the Tristan da Cunha group (Tristan, Inaccessible, Nightingale and Gough). The model will be sex-disaggregated as there are substantial differences ... Read more c b
Do catch-based indices provide a reliable index of annual recruitment for the South African anchovy population

Author: Butterworth, Doug S ; Moosa, Naseera ; Johnston, Susan J Date: 2014 The ability of catch-based measures (both catch itself and measures of catch-rate/CPUE such as catch-per-set) to provide reliable indices of abundance of the annual anchovy recruitment on the South African west coast is investigated. Ground ... Read more
Does selectivity matter? A fisheries management perspective

Author: Butterworth, Doug S ; Rademeyer, Rebecca A ; Brandão, Anabela ; Geromont, Helena F ; Johnston, Susan J Date: 2014 The authors’ experiences in relation to the estimation of selectivity and its impact on the formulation of management advice are summarised for 14 different resources. These include instances where advice (generally in the form of a catch ... Read more
Effect of the 2011 oil and soya spill events on rock lobster yields at Inaccessible and Nightingale islands

Author: Johnston, Susan J ; Butterworth, Doug S Date: 2011 Assessing the effects of the oil and soya spills resulting from the OLIVA incident at Nightingale on the lobster fisheries at the Tristan group of islands is difficult for a number of reasons: 1. the quantification of the impact of the oil ... Read more
An estimate of poaching in Area 5 using comparative catches between days of no compliance operations and when a patrol vessel was present

Author: Van Zyl, D ; Johnston, Susan J Date: 2015 Based on differences in trap catches from days with and without a patrol boat present, the annual theft by poaches from commercial traps in Area 5 is estimated to be 140 tons. For a 16 day period (covering 6 January 2015 -28 January 2015) ... Read more
Estimates of sustainable rock lobster yield for the four islands of the Tristan da Cunha group

Author: Butterworth, Doug S ; Rademeyer, Rebecca A ; Johnston, Susan J Date: 2008 The data sources upon which to assess the rock lobster resources of the islands of the Tristan da Cunha group are very limited, with original records against which to check available essentially for the last decade only (Edwards, 2007), so ... Read more
Evolution of operational management procedures for the South African West Coast rock lobster (Jasus lalandii) fishery

Author: Johnston, Susan J ; Butterworth, Doug S Date: 2005 The commercial fishery for Jasus lalandii, the South Africa West Coast rock lobster, began in the late 1800s and at its peak in the early 1950s yielded an annual catch of 18 000 t. Although this annual catch has dropped to only some 2000 t ... Read more
Final 2010 operating models for south coast rock lobster assessment update

Author: Johnston, Susan J ; Butterworth, Doug S Date: 2010 This document reports assessment results for the five final 2010 operating models (OMs) used to update the South Coast rock lobster resource assessments. These OMs contain the following modifications from the versions reported in Fisheries/ ... Read more

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