This study has used bootstrap methodology to quantify the uncertainty in toothfish biomass estimates from Chapman mark-recapture and the CPUE-by-seabed area methods in Research Blocks in Subareas 58.4 and 48.6. The Chapman mark-recapture point estimates and their confidence intervals were generally much larger than the point estimates and confidence intervals from the CPUE-by-seabed area biomass estimates.

For Patagonian toothfish in Subarea 58.4 the confidence intervals of both methods overlapped in most years, providing some confidence in the estimates from the two different methods. The large differences in Antarctic toothfish biomass estimates using the two different methods suggests that the underlying assumptions currently made in one or both of the methods are likely to be invalid.

We recommend that Working Group consider reviewing assumptions in the CPUE-by-seabed area and the Chapman biomass estimation methods at the Research Block scale and prioritise resolving issues in Research Blocks that show the largest discrepancies. 

This paper reports the preliminary results of by-catch analysis as a part of progress report for the research fishery of Dissostichus spp. in Division 58.4.3a and 58.4.4b by Japan and France during 2012/13–2016/17. We have used extracted data provided by CCAMLR secretariat on 2^nd June, 2017.

Although the by-catch occurred in most longline research operations, the number of by-catch individuals was less than 50 individuals in most of the operations. In most of longline operation, by-catch weight was less than 100 kg and less than 20 % of total catch. GRV and ANT are common by-catch species, which are caught at every research block and every year. RFA is also common by-catch species, but mainly fished at the research block 58.4.3a.

The results of the GLM and its model selection with AIC criteria indicates that the number of by-catch individuals is highest at the research block 58.4.4b_1 for GRV and ANT. As temporal change of by-catch, common three by-catch species represents obvious decrease in number of by-catch individuals. The results of GLMs also imply the influence of fishing method and gears on the by-catch pattern.

This paper reports the preliminary results of by-catch analysis as a part of progress report for the research fishery of Dissostichus spp. in Subarea 48.6 by Japan and South Africa during 2012/13–2016/17. We have used data set provided by CCAMLR secretariat on 10^th May, 2017.

Although the by-catch occurred in most longline research operations, the number of by-catch individuals was less than 100 individuals in most of the operations. In most of longline operation, by-catch weight was less than 100 kg and less than 20 % of total catch. GRV and ANT are common by-catch species, which are caught at every research block and every year. ICX is also common by-catch species, but mainly fished at the ice ridge research blocks 48.6_4 and 48.6_5.

The results of the GLM and its model selection with AIC criteria indicates that the number of by-catch GRV individuals is higher at southern research blocks (48.6_3, 48.6_4, and 48.6_5). On the other hands, the number of ANT by-catch individuals is highest at research blocks 48.6_1. As temporal change of by-catch, only GRV shows obvious decrease in number of by-catch individuals.

The subarea 88.3 is a large area contained from 105° W to 70° W where has been closed to directed fishing following the results of a Chilean survey activities in 1998 (SC-CCAMLR-XVII/BG/7). Previous three research surveys conducted by the New Zealand and the Russian flagged vessels since 1998. It was noted that 8 D. Mawsoni were tagged by the New Zealand in the 2004/05 season and 123 D. Mawsoni were tagged by Russian flagged vessels in the 2010/11 and 2011/12 season (WG-FSA-05/53, WG-FSA-11/36 & WG-FSA-12/13). It was also noted that no tagged fishes were recaptured during the previous research activities. Considering this large region, the Republic of Korea notes that only 95 research hauls and 131 tagged fishes from three research activities (in total since 1998) were not enough likely to recapture. it was further noted that there was no research activities more than two consecutive years in the past despite the Scientific Committee has agreed that research fishing should be conducted such that it results in an assessment of a stock in 3-4 years time (SC-CAMLR XXVIII, paragraphs 4.165). During the 2016/17 season the Korean flagged vessel, Greenstar, conducted 2^nd year research in this area. Total of 957 D. Mawsoni were tagged and released. Although the Greenstar set 95 research hauls in the Subarea 88.3 she did not find any recaptures of previous surveys. In third research year, the Greenstar is planning to revisit to the areas where the tagged fishes were released to further understand toothfish movement and migration with recapture data.

The Ross Sea region MPA Research and Monitoring Plan Workshop (WS-RMP) was held at the Palazzo Farnesina (Ministry of Foreign Affairs and International Cooperation, MAECI) in Rome from 26–28 April 2017.

The purpose of the workshop was to develop a draft research and monitoring plan (RMP) for the Ross Sea region MPA. The RMP is required to be introduced to CCAMLR at the annual meetings of the Scientific Committee and Commission later this year, prior to the Ross Sea Region MPA’s implementation in December 2017.

Following the workshop, the conveners submitted the draft research and monitoring plan to the Ross Sea MPA implementation e-group. Since then, two comments have been submitted to either the e-group or to the conveners directly. These comments attached at the end of this document.

The Antarctic toothfish stock assessment for the Ross Sea region (Subareas 88.1 and 88.2AB) will be updated in 2017. The introduction of CM 91-05 (the Ross Sea region Marine Protected Area) will require modifications to the previous method the estimation of catch splits in the calculation of precautionary yields. In addition, work will need to be carried out in the longer term that consider how the assessment will need to be modified to respond to changes in the fishing catch and effort distributions that may result from the implementation of the Ross Sea region MPA.

An update of the 2015 stock assessment is proposed for the 2017 stock assessment which will maintain the current structure of the model while including updated catch, age-frequency, and tag-release and recapture data. Yield projections should be run that incorporate short term catch split options as required by CM 91-05. Additional options could also be developed for catch splits between the shelf, slope and north areas prior to the 2019 assessment. Sensitivities to a base case model that investigate the robustness of model assumptions or arise from the considerations of model diagnostics should also be conducted.

The Amundsen Sea region (ASR) is currently managed under a research plan, which has shown promising results to date, with 8 interseason tags recaptured in the South area in 2016 and 12 (preliminary recaptures) in 2017. The aim of this paper is to ascertain when the Amundsen Sea region stock assessment model is likely to provide management advice, and to investigate the effects of using either two independent single-area models or a two-area model.

We used simulations to investigate the expected precision in estimates of biomass, the likely biases, and to set expectations for mark-recapture data for the next few years to predict progress towards a robust assessment model using the two-area model. The models showed that using two independent models lead to higher estimates of biomass in the North and lower estimates of biomass in the South, but that the two independent models fitted the data poorly. Simulations suggest that the current research plan with the current levels of catch and tagging rate is likely to deliver the information that would generate a robust estimate of biomass in the ASR in the future. We also found that it is likely that we would observe very few tags moving between the areas and that increasing the tagging rate in the South would result in an increase in bias but no improvement in the precision of the estimation of stock biomass.

We therefore recommend (i) future work using independent methods to understand toothfish movement within the ASR (such as PSAT tags or otolith microchemistry), and (ii) the current research plan be continued for the next season, and (iii) a two-area model continue to be developed to assess the ASR for 2018, as recommended by Scientific Committee in 2016.

At its 2011 meeting, the Scientific Committee agreed that a time series of relative abundance from a well-designed survey could be a useful input into the Ross Sea stock assessment model. In this paper we provide results of the sixth annual survey in the time series. The objectives of this survey included monitoring sub-adult (≤ 110 cm TL) toothfish in the south of SSRUs 881.J and 881.L in the southern Ross Sea (Strata A–C) using standardised gear in a standardised manner; and monitoring trends in larger (large sub-adult and adult) toothfish in two areas (both situated in SSRU 881.M) of importance to predators: Terra Nova Bay in 2017, with McMurdo Sound surveyed in 2016.

The estimated relative biomass index of toothfish for the core strata showed an increase to the maximum observed in the time series. Scaled length frequencies for the core strata indicate the progression of a strong year class that appears in 2012 progressing through each year, with the appearance of a second strong cohort in 2015. The decline in relative biomass during the survey time series is consistent with the decline in abundance of this 2012 cohort through time, through mortality and the movement of older fish out of the survey core area, as well as the weaker subsequent year classes. A second, strong cohort is evident entering the population in 2015, with a subsequent increase in biomass in 2016 and 2017. These results suggest the surveys are indexing local abundance and age structure, and are providing a reliable means of monitoring recruitment, estimating recruitment availability and year class strength.

Higher than expected catch rates early in the survey necessitated the reduction of station density in the core strata to avoid exceeding the catch limit. As a result of sampling fewer stations in the core strata, the variance of survey estimates was higher than in previous surveys. The higher than expected catches required an adaptive survey design to maintain a scientifically robust and comparable survey whilst constraining catch to below the catch limit. Principles to follow while adapting the survey to unexpected circumstances may be useful for others conducting longline surveys in CCAMLR fisheries.

This paper proposes to continue the Ross Sea shelf toothfish survey for the next five years, 2018–2022. The first objective of the survey is to monitor toothfish recruitment in the southern Ross Sea (core strata). This is a continuation of the yearly time series of research surveys of these strata carried out since 2012. It is important to continue the time series as the data collected provide essential input to the stock assessment to estimate year class strength which is used to inform management decisions. The second objective is to monitor trends in larger (large sub-adult and adult) toothfish abundance in alternate years in McMurdo Sound and Terra Nova Bay where toothfish may form an important part of the diet of Type C killer whales and Weddell seals. The third objective is to collect and analyse a wide range of data and samples from these areas (e.g. benthic invertebrates, stomach and tissue samples, and acoustic data). Both objectives two and three are specified as high priority research topics in the research and monitoring plan for the Ross Sea region MPA. The survey design will remain consistent with previous years. Different catch limits are requested on alternate year to account for the different catch rates in McMurdo Sound and Terra Nova Bay. The results of each survey and trends in the time series will be presented to WG-FSA for review each year and the results included in the stock assessment. A full review will be completed and presented to WG-SAM, WG-EMM, and WG-FSA in 2022.

New Zealand proposes to contribute to a multi-member research plan to sample the toothfish population in Subarea 88.3. Although this has been written as a stand-alone proposal, the intention is to develop a single co-ordinated research plan with Korea and any other members who may wish to conduct research in this subarea. There is considerable uncertainty about the abundance of Antarctic toothfish in Subarea 88.3 and the Scientific Committee has requested members complete research in this area to address that uncertainty. There is also considerable uncertainty about the stock structure of Antarctic toothfish in this subarea – and their relationship to the rest of the Pacific Sector. Korea have already developed a research plan for this subarea, but there are several regions and features which are not currently being surveyed. This research proposal is designed to complement Korea’s research plan by focusing research on the abundance of toothfish on two of the northern features, as well as parts of the slope and southern shelf where little fishing has occurred. The two main objectives of the proposal are: (i) to determine the abundance of Antarctic toothfish in Subarea 88.3; and (ii) to improve understanding of stock structure of toothfish in this area. To complete the effort-limited survey a total of 65 sets is required. We estimate a maximum catch of 95 tonnes may be required to ensure the survey objectives can be met.