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Browsing by Author "Sakai, Osamu"

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Brief examination of conditioning results of the SBT operating model for management procedure evaluation

Author: Kurota, Hiroyuki ; Sakai, Osamu ; Butterworth, Doug S Date: 2010 Updated conditioning results for the operating model used for evaluation of management procedures are examined briefly. Although no serious problems are found, the examination shows that: (1) higher steepness is preferred in the grid sampling ... Read more
A check of operating model predictions from the viewpoint of the management procedure implementation in 2016

Author: Takahashi, Norio ; Kurota, Hiroyuki ; Sakai, Osamu ; Itoh, Tomoyuki ; Butterworth, Doug S Date: 2016 Values of the core vessels’ longline CPUE and aerial survey (AS) indices (two required inputs to the Bali management procedure) are compared to projection results obtained from the operating model (OM). Recent observations for the CPUE index ... Read more
A check of operating model predictions from the viewpoint of the management procedure implementation in 2017

Author: Takahashi, Norio ; Sakai, Osamu ; Kurota, Hiroyuki ; Itoh, Tomoyuki ; Butterworth, Doug S Date: 2017 Values of the core vessels’ longline CPUE and aerial survey (AS) indices (two required inputs to the Bali management procedure) are compared to projection results obtained from the SBT operating model (OM). The most recent observations for ... Read more
Conditioning of the SBT operating model to inform projection specifications

Author: Sakai, Osamu ; Kurota, Hiroyuki ; Takahashi, Norio ; Butterworth, Doug S Date: 2011 The effects of updates on the operating model are examined. Because of the new growth schedule and the most recent two years’ data, the operating model prefers somewhat higher steepness compared to the previous version. This difference has ... Read more
Examination of the SBT operating model to inform conditioning and projection specifications

Author: Kurota, Hiroyuki ; Sakai, Osamu ; Butterworth, Doug S Date: 2009 Stock assessments and constant catch projections have been conducted using the Operating Model (OM) specified at the CCSBT technical meeting held in Seattle in July 2009. The current analysis shows that: (1) for the base case, higher steepness ... Read more
Exploration of empirical management procedures based on longline CPUE index and aerial survey index

Author: Kurota, Hiroyuki ; Fujioka, Ko ; Sakai, Osamu ; Butterworth, Doug S Date: 2010 We evaluated performance of four Management Procedures (MPs) with empirical algorithms to determine TACs using information from the longline CPUE series and the aerial survey index. This MP exercise shows that TAC levels in the future are ... Read more
Further evaluation of empirical management procedures based on longline CPUE index and aerial survey index

Author: Kurota, Hiroyuki ; Fujioka, Ko ; Sakai, Osamu ; Takahashi, Norio ; Butterworth, Doug S Date: 2010 Based on recommendations made during the third Operating Model and Management Procedure Technical Meeting (June 2010, Seattle), we have revised and evaluated “HK” Management Procedures (MPs) using empirical algorithms to determine TACs using ... Read more
Further examinations of the SBT operating model to explore new tagging model and grid specifications

Author: Kurota, Hiroyuki ; Sakai, Osamu ; Takahashi, Norio ; Butterworth, Doug S Date: 2009 Stock assessments and constant catch projections were conducted using new Operating Models (OMs; sbtmod21 and sbtmod22, which have different tagging models) developed by the CCSBT ESC. The current analysis showed that: 1. a new candidate for ... Read more
Performance of the empirical management procedure (MP2) under the updated operating models

Author: Kurota, Hiroyuki ; Takahashi, Norio ; Sakai, Osamu ; Butterworth, Doug S Date: 2011 We evaluated the performance of the empirical management procedure (MP2) using the updated operating model (reference set and robustness trials). In order to meet management targets, TACs need to be increased steadily and substantially under ... Read more
SBT stock assessment and projection under overcatch scenarios using the Operating Model

Author: Kurota, Hiroyuki ; Butterworth, Doug S ; Sakai, Osamu Date: 2006 Stock assessments and constant catch projections under several overcatch scenarios using the operating model developed by CCSBT SC are conducted. The main factors influencing the assessment results are (1) the period over which the longline ... Read more
A scientific alternative to moratoria for rebuilding depleted international tuna stocks

Author: Hillary, Richard M ; Preece, Ann L ; Davies, Campbell R ; Kurota, Hiroyuki ; Sakai, Osamu ; Itoh, Tomoyuki ; Parma, Ana M ; Butterworth, Doug S ; Ianelli, James ; Branch, Trevor A Date: 2015 There is considerable international concern and scientific debate about the current state and future of tuna stocks worldwide and the capacity of Regional Fisheries Management Organisations to manage the associated fisheries effectively. In ... Read more