Noting the large increase in new research proposals tabled targeting toothfish across the Convention Area, and the relative lack of progress in achieving research objectives in some areas, WG-SAM-17 recommended that the procedures for research plan proposals in data poor fisheries be compiled and further developed to bring together the advice from the Scientific Committee and its Working Groups in one place, to provide context and direction where the process has not previously been specified, and to provide recommendations for the Scientific Committee to consider with regard to a CCAMLR strategy to manage progress and ensure success of research plans in data poor fisheries. We provide a chronology of the advice developed since 2011, when data-poor fisheries were first acknowledged in Conservation Measure 41-01, and provide recommendations for streamlining the review of new and ongoing research plans. As noted by the Scientific Committee and its Working Groups, we see benefit in an increased emphasis on multi-member collaboration, and firm commitment to ‘off the water’ research milestones such as ageing otoliths, analysing samples and data to inform stock hypotheses, and developing capability in conducting robust stock assessments.

The CAMLR Scientific Committee in 2016 reviewed three scientific background documents in support of the development of a CCAMLR MPA in the Weddell Sea. Germany was asked to carry out further work, in particular regarding the issues and questions raised at WG-EMM-16 and SC-CAMLR-XXXV.

Here, the Delegation of Germany intends to update the Scientific Committee on the current state of the work carried out during the 2016/2017 intersessional period. Chapter 1 of this working group paper informs on the new data retrieval process. Chapter 2 presents the updated analyses of relevant data layers, including an update on the Antarctic toothfish habitat model. Chapter 3 provides a sensitivity analysis of the level of protection for Antarctic toothfish and other demersal fish that explores a range of protection-level scenarios. In this context, we show how the cost layer works. Subsequently, a revised Marxan approach based on the updated data layer is shown. In Chapter 4 we outline the way we - at that stage -transferred the results of the scientific analyses into the WSMPA borders and management zones.

In addition, Germany already took into account a number of recommendations made by WG-EMM-17, such as the use of the recursive Marxan procedure and the spatial projection of data. Some other improvements that were suggested by WG-SAM-17 and WG-EMM-17 (e.g., the reliability of the sparse data sets, the development of separate cost layers for krill and toothfish) will be reported to the CCAMLR Working Groups in 2018.

In Division 58.4.3a, since 2012, research fishing has been conducted in the research block by two vessels using longline: “Shinsei Maru No. 3” (Japan) and the “Saint André” (France). The catch limit for Dissostichus spp. is 32 tonnes in 2014/2015 and the total reported catch up was 16.3 tonnes. For the season (2015/16), the catch limit was unchanged (32 tonnes) but no catch up was reported due to engine damage for the French vessel and no fishing activity in the area for the Japanese vessel. For 2017, one vessel from France visited Division 58.4.3a for a catch of 1.68 tonnes. The Japanese-flagged vessel did not undertake fishing research activity in 2017. The first Franco-Japanese exploratory longline fishery research plan for Dissostichus spp. in Division 58.4.3a (WG-FSA-16/55) was presented to WG-FSA-16, which included research objectives, methods and milestones in accordance with Conservation Measure 41-06 and associated measures. In October 2016, the Scientific Committee agreed that the research plan is appropriate to achieve its objectives (SC-CAMLR-XXXV, para. 3.251), and recommended to carry on a couple of investigations for the following years (SC-CAMLR-XXXV, para. 3.250). France and Japan commonly notifies their intention to continue their exploratory fisheries in Division 58.4.3a over the coming years in order to contribute to the tagging program and to achieve a robust stock assessment. We present here a proposal for the continuation of the research plan as set out in WG-FSA-16/55, and taking into account the Scientific Committee’s recommendations.

Macrourus spp. are the major by-catch species in the exploratory toothfish fishery in Divisions 58.4.1 and 58.4.2. CCAMLR has previously identified three main steps to minimise bycatch; i) avoidance, ii) mitigation and iii) the setting of sustainable by-catch limits if mortality is not preventable (SC-CAMLR-XXII, paragraph 5.230). Here, we undertake a risk assessment of the effects of exploratory fishing for D. mawsoni on Macrourus spp. in Division 58.4.1 and 58.4.2 in general and in research block 58.4.1_6 in particular.

We investigate the distribution of D. mawsoni and Macrourus spp. catch rates in research block 58.4.1_6, and conclude that the current research grid includes fishing locations with high Macrourus spp. by-catch rates in depths between 750 m and 1150 m. To mitigate Macrourus spp. by-catch in future fishing seasons, we propose to either (1) modify the research grid such that the grid includes only areas of low Macrourus spp. by-catch rates, or (2) replace the requirement for vessels to fish within the research grid with structured fishing. The latter option is similar to research fishing in other research blocks within Division 58.4.1 that do not have research grids, where fishing effort is distributed across a range of depth strata (<1000, 1001–1500, 1501–2000 m) with at least 5 longlines in each depth strata per fishing member.

We also provide estimates of biomass and sustainable catch for the M. whitsoni species morph in all research blocks of Division 58.4.1 and 58.4.2 by applying the CPUE-by-seabed-area method using biomass estimates of M. whitsoni from the 2008 Ross Sea assessment as the reference biomass. Macrourus spp. biomass was estimated separately by longline gear type in each research block due to differences in reported catch rates. We recommend that the biomass and sustainable catch estimates from autoline, and if not available, from trotline be considered as the basis for management advice.

This paper presents an update on the ageing of Antarctic toothfish, Dissostichus mawsoni, from East Antarctica (Division 58.4.1) and the Amundsen Sea (Subarea 88.2).  Initially, experienced readers at the Australian Antarctic Division (AAD) read a subset of 40 otoliths from the New Zealand reference collection for Antarctic toothfish, with all pairwise comparisons between readers and against the New Zealand reference ages showing a high level of precision (all IAPE < 5%, CV < 7%). Sister pairs of Antarctic toothfish otoliths were also prepared, one using the ‘bake and embed’ method and the other by thin sectioning, in order to assess the comparability of age estimates derived from each method. The values of IAPE and CV were acceptable between the two methods of preparation for individual readers, and between readers for each of the methods (all IAPE < 5%, CV < 6%). The level of ageing precision between the ‘bake and embed’ and ‘thin section’ methods for each reader was particularly high (all IAPE < 2%, CV < 3%), confirming that a similar level of detail is revealed by each preparation method. Therefore, either method can be used to provide reliable age estimates for Antarctic toothfish. Finally, a total of 730 otoliths from Antarctic toothfish which were collected by an Australian vessel in Subarea 88.2 in the 2014-2015 season and in Division 58.4.1 in the 2015-2016 season, were aged using thin sections (IAPE = 2.88, CV = 4.07).  The age estimates provided by this study will be available for use in the estimation of biological parameters and stock assessments of the respective sampling areas in East Antarctica and the Amundsen Sea.

Exploratory longline fisheries targeting mainly Antarctic toothfish (Dissostichus mawsoni) have been operating in Divisions 58.4.1 and 58.4.2 since 2003, however robust stock assessments and catch limits according to CCAMLR decision rules have yet to be developed. A key step in developing management advice in these Divisions is understanding the distribution, abundance and boundaries of the target stock. WG-FSA-16/29 outlined the first multi-member toothfish exploratory fishery research plan, including research objectives, methods and milestones. Within this plan, milestones 1.5 and 2.1 involve the development of stock structure hypotheses and spatially-explicit habitat-use models. Accordingly, this paper reports on the development of generalised additive mixed models to characterise relationships between environmental variables and (1) relative density, (2) mean weight, (3) proportion mature and (4) sex ratio of D. mawsoni, including in adjacent Division 58.4.3b. Spatial heterogeneity in catch composition indicated that D. mawsoni were not randomly distributed across the area. Models were used to generate predictions of D. mawsoni density and composition across a broad spatial scale, and revise hypotheses relating to the structure and functioning of the stock.

This paper presents an updated assessment for the Patagonian toothfish (Dissostichus eleginoides) fishery at Heard Island and McDonald Islands in CCAMLR Division 58.5.2 with data until end of the season 2015/16. The updated assessment model is based on the best available estimates of model parameters, the use of abundance estimates from a random stratified trawl survey (RSTS), longline tag-release data from 2012-2015 and longline tag-recapture data from 2013-2016, and auxiliary commercial composition data to aid with the estimation of year class strength and selectivity functions of the trawl, longline and trap sub-fisheries.

Compared to the 2015 assessment that was accepted by WG-FSA-15 to be used for management advice, this assessment takes into account (1) new fishery observations up to the end of 2016 including new ageing data from the RSTS and commercial fishery from 2015-2016, (2) updated growth parameters, (3) updated maturity parameters, (4) updated tag loss estimates (5) a bias correction for fish emigrating out of Division 58.5.2, (6) survey biomass and catch proportions instead of survey abundance numbers, and (7) iterative data weighting using the ‘Francis’ method. All model runs were conducted with the CASAL version 2.30-2012-03-21 rev. 4648 that was agreed on by WG-SAM-14.

The updated assessment model leads to a smaller estimate of the virgin spawning stock biomass B₀ than that obtained in 2015, with an MCMC estimate of 77 286 tonnes (95% CI: 71 492-84 210 tonnes). Estimated SSB status was 0.61 (95% CI: 0.58-0.64). Despite the smaller biomass, changes to the model compared to 2015 in particular its higher productivity with the updated maturity parameters, meant that the catch limit that satisfies the CCAMLR decision rules has increased from 3405 tonnes to 3525 tonnes.

CCAMLR XXXIV (para. 5.68) endorsed new pre-season (1-14 April) and post-season (15-30 November) trial season extensions, in addition to existing pre-season (15-30 April) and post-season (1-14 November) trial extensions in the Patagonian toothfish longline fishery in Statistical Division 58.5.2 (WG-FSA-15/48).

Australia undertook to report annually on the results of all the trials. This paper presents information on fishing effort and seabird interactions with fishing gear collected during the periods 1-14 November 2016, 15-30 November 2016, 1-14 April 2017 and 15-30 April 2017. This report complements the fishing effort and interaction data reported in 2015 (WG-FSA-15/48) and 2016 (WG-FSA-16/28r1).

Tag-loss or tag-shedding rates for tagged fish in the Patagonian toothfish (Dissostichus eleginoides) fisheries at Heard Island and McDonald Islands (HIMI) in Division 58.5.2 were estimated following the method proposed by Adam & Kirkwood (2001). Tag-loss rates were generally low, with longline-caught and recaptured fish losing their tags quicker than trawl-caught and recaptured fish. With an initial tag-loss proportion of 2.8% and ongoing tag-loss rate of 0.056 in the longline fishery, 99.3% of all double-tagged fish retain at least one tag after one year, and 80.2% after ten years. The parameter of annual tag-loss rate in CASAL’s single-tag model was approximated, for a maximum time at liberty of 6 years, as l = 0.014 for longline and l = 0.007 for trawl. However, this single tag-loss rate for longline varied strongly between time periods, with l = 0.007 for 2003-2006, l = 0.021 for 2007-2011, and l = 0.006 for 2012-2015. We recommend that for longline releases the parameter estimates for these time periods be used in the stock assessment for Patagonian toothfish in Division 58.5.2.