WG-SAM-2022

The Scientific Committee requested DSAG to review the Rules for access and use of CCAMLR Data, which was presented for consideration at the Scientific Committee symposium. This document describes the implementation of the Rules for Access and use of CCAMLR Data into the CCAMLR Data Request procedure and the procedure for Read More
Presentado por:
Dr Anton Van de Putte (Bélgica)

Aprobado por:
Dr Anton Van de Putte (Bélgica)

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This document is intended to address several issues related to the development of recruitment indices for Antarctic krill from net-tow data. We address three primary issues: 1) the view that length-frequency data collected by long-term monitoring programs that have used nets other than the RMT-8 cannot be used to parameterize Grym simulations, 2) that Read More
Presentado por:
Dr Christian Reiss (Estados Unidos de América)

Aprobado por:
Dr George Watters (Estados Unidos de América)

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Proportional recruitment is a concept that summarizes the variability of new individuals entering a population over time. Two parameters characterizing proportional recruitment, the mean and standard deviation of the interannual proportion of juveniles in the population, are important inputs to the Generalised Yield Model in R (GRYM). The GRYM is a simulation framework that defines Read More
Presentado por:
Dr Doug Kinzey (Estados Unidos de América)

Aprobado por:
Dr George Watters (Estados Unidos de América)

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Aiming to develop a method to estimate the length-weight relationship for concurrent acoustic monitoring of Antarctic krill biomass, a pilot experiment was undertaken to evaluate the feasibility of measuring the weight of fresh Antarctic krill at sea by scientific observers onboard krill fishing vessel, where multiple individuals of the same length class was weighed Read More
Presentado por:
Dr Xianyong Zhao (China)

Aprobado por:
Dr Xianyong Zhao (China)

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This paper proposes a continuation of the Ross Sea shelf survey (RSSS) for three years from 2023–2025. The primary objective (1) of the survey is to monitor Antarctic toothfish recruitment in the southern Ross Sea. This would be a continuation of the annual time series of research surveys carried out since 2012 using a random stratified design. Continuing the time series is Read More
Presentado por:
Mr Nathan Walker (Nueva Zelandia)

Aprobado por:
Mr Nathan Walker (Nueva Zelandia)

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This is the second year continuation of the on-going three-year plan from 2021/22 to 2023/24. There is no significant change from the endorsed proposal (WG-FSA-2021/38).

An analysis of the Sea Ice Concentration (SIC), Sea Surface Temperature (SST) and winds in Research Blocks (RBs) 48.6_5 and 48.6_4 is presented. The SIC in RB5 between mid Feb. and end Mar. 2022 were the lowest for the 2019-2022 period. RB4 was free of ice (SIC 0%) in Jan. and Feb. 2022.

A Read More
Presentado por:
Mr Roberto Sarralde Vizuete (España)

Aprobado por:
Mr Roberto Sarralde Vizuete (España)

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Exploratory fishing for Antarctic toothfish (Dissostichus mawsoni) in East Antarctica (Divisions 58.4.1 and 58.4.2) began in 2003. While preliminary integrated stock assessments have been developed for these Divisions, robust estimates of stock biomass and precautionary catch limits according to CCAMLR decision rules remain to be determined. Read More
Presentado por:
Dr Philippe Ziegler (Australia)

Aprobado por:
Dr Philippe Ziegler (Australia)

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A research plan for Subarea 88.3 was commenced by Korea in 2016 under CM 24-01, New Zealand joined the proposal in 2017. The joint research proposal was for 3 years covering the period 2017/18, 2018/19 and 2019/20. It was designed to build on Korea’s previous research by continuing to focus Read More
Presentado por:
Dr Sangdeok Chung (República de Corea)

Aprobado por:
Ms Jung-re Riley Kim (República de Corea)

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Exploratory fishing for Antarctic toothfish (Dissostichus mawsoni) in East Antarctica (Divisions 58.4.1 and 58.4.2) began in 2003. While preliminary integrated stock assessments have been developed for these Divisions, robust estimates of stock biomass and precautionary catch limits according to CCAMLR decision rules remain to be Read More
Presentado por:
Dr Philippe Ziegler (Australia)

Aprobado por:
Dr Philippe Ziegler (Australia)

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We present revisions to the reporting of the trend analysis results following reviews in 2021. Preliminary

biomass estimates for research blocks in data-limited toothfish fisheries and the resulting preliminary catch

limits for the 2023 season have been determined using the updated trend analysis decision rules. The resulting

preliminary catch limits are for Read More
Presentado por:
Dr Stéphane Thanassekos (Secretaría de la CCRVMA)

Aprobado por:
Dr David Agnew (Secretaría de la CCRVMA)

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Exploratory fishing for Antarctic toothfish (Dissostichus mawsoni) in East Antarctica (Divisions 58.4.1 and 58.4.2) began in 2003. Since 2017/18, exploratory fishing has been conducted under successive research plans by Australia, France, Japan, Republic of Korea and Spain. Here, we review and update the hypothesis for toothfish stock structure across East Antarctica Read More
Presentado por:
Dr Philippe Ziegler (Australia)

Aprobado por:
Dr Philippe Ziegler (Australia)

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Aiming to develop a method to estimate the length-weight relationship for concurrent acoustic monitoring of Antarctic krill biomass, a pilot experiment is undertaken to evaluate the feasibility of measuring the weight of fresh Antarctic krill at sea by scientific observers onboard krill fishing vessel, where multiple individuals of the same length Read More
Presentado por:
Dr Yi-Ping Ying (China)

Aprobado por:
Dr Xianyong Zhao (China)

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The paper studies the dynamics of odor release for different types of bait (squid, fish) . The direct spectrophotometric registration was used for the quantitative determination of proteins realized from baits in seawater. It has been shown nonlinear characteristics of odor release in water. An active release occurs twice - during the first three days and after nine-ten days after Read More
Presentado por:
Dr Svetlana Kasatkina (Federación de Rusia)

Aprobado por:
Dr Svetlana Kasatkina (Federación de Rusia)

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Some aspects of acoustic- trawl surveys for the mackerel icefish (Champsocephalus gunnari) assessment in the CCAMLR Statistical Subarea 48.3 as fish with a semi-pelagic distribution are discussed.

It is proposed that present-day icefish survey in  Subarea 48.3 would represents complex Read More
Presentado por:
Dr Svetlana Kasatkina (Federación de Rusia)

Aprobado por:
Dr Svetlana Kasatkina (Federación de Rusia)

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Knowledge of recruitment dynamics, and in particular trends in recruitment and recruitment variability, are key inputs for integrated assessments of fish stocks. A quantitative longline survey monitoring the recruitment of Antarctic toothfish (Dissotichus mawsoni) in the southern Ross Sea was started in 2012. The survey was expanded in 2016 to monitor trends and biological Read More
Presentado por:
Mr Nathan Walker (Nueva Zelandia)

Aprobado por:
Mr Nathan Walker (Nueva Zelandia)

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The software platform CASAL (C++ algorithmic stock assessment laboratory) has been used to implement integrated statistical catch-at-age toothfish stock assessments in CCAMLR since 2005. However, CASAL is no longer being developed or maintained. The software platform Casal2 has been developed as a more generalised framework for implementing Bayesian integrated catch-at-age (or Read More
Presentado por:
Mr Nathan Walker (Nueva Zelandia)

Aprobado por:
Mr Nathan Walker (Nueva Zelandia)

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In this paper, we present methods developed to predict spatio-temporal changes in macrourid bycatch in the Ross Sea region Antarctic toothfish (Dissostichus mawsoni) fishery and some preliminary results. Our methods rely on VAST (vector autoregressive spatio-temporal) models fitted to catch rate data of Macrourus whitsoni and M. caml collected by Read More
Presentado por:
Mr Nathan Walker (Nueva Zelandia)

Aprobado por:
Mr Nathan Walker (Nueva Zelandia)

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This paper presents a development tool for generating simulated multiyear surveys from longline C2 data containing catch, effort and observer sampling observations. The tool resamples historic catch and observer data according to randomly selected or prespecified survey haul locations, applying user specified conditions (e.g. gear type). It allows statistical Read More
Presentado por:
Ms Georgia Robson (Reino Unido)

Aprobado por:
Dr Chris Darby

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Accounting for tag loss rate is an important step in reducing bias in tag-based stock size estimates in CASAL. Here, we used 10,968 records of double-tagged Patagonian toothfish (Dissostichus eleginoides) released in Subarea 48.3 between 2004 and 2020, that were recaptured with at least one tag, to estimate tag loss rates over time at liberty. We explored Read More
Presentado por:
Ms Georgia Robson (Reino Unido)

Aprobado por:
Dr Chris Darby

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The CCAMLR Scientific Committee has noted that there is a need to consider developments to the CCAMLR Decision Rule, including the potential utility of target and limit exploitation rate objectives to increase its robustness. WG-SAM has been tasked with this in its future workplan. 

The CCAMLR Decision Rule as applied to Read More
Presentado por:
Ms Georgia Robson (Reino Unido)

Aprobado por:
Dr Chris Darby

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This paper presents the diagnostics associated with the Subarea 48.4 Patagonian toothfish (Dissostichus eleginoides) stock assessment models presented in Readdy et al. (2022) using the integrated CASAL assessment (Bull et al., 2012).

This work presents updates to the stock assessment of Patagonian toothfish (Dissostichus eleginoides) in Subarea 48.3 following the recommendations of WG-FSA-2021. Additional otolith readings from the period 2012-2017 are also considered for inclusion in the assessment. Additionally, a revision to the fitting of the survey abundance index is presented. Read More
Presentado por:
Ms Georgia Robson (Reino Unido)

Aprobado por:
Dr Chris Darby

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Alternative models are presented for discussion to address a lack of convergence in the CASAL model fit to Patagonian toothfish (Dissostichus eleginoides) in Subarea 48.4 owing to the increasing quantity of data. Of the models that converged successfully the outcomes showed very similar diagnostic results, particularly the MPD fits. The main differences between the Read More
Presentado por:
Ms Georgia Robson (Reino Unido)

Aprobado por:
Dr Chris Darby

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This paper presents the diagnostics associated with a 48.3 Patagonian toothfish assessment step 5.

Data limited analysis is applied to tagging returns to determine estimates of exploitation rates (fishing mortality) on the Patagonian toothfish (Dissostichus eleginoides) stock in Subarea 48.3. The results show that the tagging data collected from the fishery can be analysed in a way that is consistent with the simple assumptions of catch Read More
Presentado por:
Ms Georgia Robson (Reino Unido)

Aprobado por:
Dr Chris Darby

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This paper compares the influence of otolith selection for age reading, from observer collected samples, on the estimation of the biological productivity parameters, maturity at age and expected length at age, for Patagonian toothfish (Dissostichus eleginoides) in Subarea 48.3 between 2011 and 2020.

The scientific research fishing was conducted by the Greenstar (KOR) and Marigolds (UKR) in in Subarea 88.3 following the survey design (WG-FSA-2021/34). The total catch of D. mawsoni was 128909.3 kg comprising 4984 individuals. The CPUE for Dissostichus mawsoni varied among the research blocks; CPUE was Read More
Presentado por:
Dr Kostiantyn Demianenko (Ucrania)

Aprobado por:
Dr Kostiantyn Demianenko (Ucrania)

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The GrYM model is now ready for used in the new krill management approach. However, some of the important model input parameters were still to be determined. The present paper introduced briefly the status of the model parameter developments to contribute to the discussion at WG-SAM-2022.

The review of the available gear selectivity studies in the krill fishery in context of standard ICES methods was undertaken.  Some methodical aspects of selectivity estimates were considered.  According to the authors, currently, the data sets used to estimate the gear selectivity does not adequately describe the krill fishing process.

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Presentado por:
Dr Svetlana Kasatkina (Federación de Rusia)

Aprobado por:
Dr Svetlana Kasatkina (Federación de Rusia)

Precautionary yield ('gamma', the proportion of stock biomass harvested annually) for the Antarctic krill fishery is currently chosen by comparing krill spawning stock biomass (SSB) during 20-year model projections to pre-exploitation spawning stock biomass (SSB0). Both SSB and SSB0 are simulated for these projections using input data considered known. Precautionary yield derived Read More
Presentado por:
Dr Doug Kinzey (Estados Unidos de América)

Aprobado por:
Dr George Watters (Estados Unidos de América)

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Following the request by WG-SAM-2021 (SC-CAMLR 2021a, para. 10.3) and the presentation of the preliminary krill stock assessment in Maschette et al. (2021a; 2021b) to WG-FSA-2021 (SC-CAMLR 2021b, paras. 5.8 - 5.13), a training workshop on running the krill assessment models fitted using the Grym package (Maschette et al. 2019) was held on 13^th and 14^th Read More
Presentado por:
Dr Philippe Ziegler (Australia)

Aprobado por:
Dr Philippe Ziegler (Australia)

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Casal2 is an open-source integrated statistical catch-at-age assessment tool for modelling the population dynamics of marine populations. Casal2 is designed for quantitative assessments of marine populations, including fish, invertebrates, marine mammals and seabirds.

Casal2 implements generalised age (Casal2 for age-based models) or length structured (Casal2 for length-based models) Read More
Presentado por:
Mr Nathan Walker (Nueva Zelandia)

Aprobado por:
Mr Nathan Walker (Nueva Zelandia)

Publicación:
NIWA Technical Report, 139 (2022): ISSN 1174-2631. User manual for age-based models with Casal2 v22.06 (2022-06-07)

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