In 2016, changes to the methods used by CCAMLR to estimate biomass in research blocks resulted in conflicting estimates of biomass between the CPUE by seabed area and the Chapman estimate. The Scientific Committee requested that the changes to the methods be reviewed, that scientific rational for the different biomass estimates be provided.

In this paper, we develop a modified CPUE by seabed area method that improves on the original CPUE by seabed area method for toothfish populations in research blocks. This uses local Chapman biomass estimates in the reference area instead of the stock biomass estimated by the stock assessment model as the reference biomass. We demonstrate evidence of a linear relationship between CPUE and fish density in the Ross Sea reference area for the first time. The resulting density estimates from Shelf/Slope and North habitat types from the Ross Sea can be used to estimate a CPUE by seabed area biomass in designated research blocks.

We also develop a Bayesian approach that combines the information from the CPUE by seabed area biomass analogy and Chapman biomass estimates together in an integrated statistical to provide robust estimates of biomass in research blocks.

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 authors intend to update the CCAMLR Working Groups 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 transferred the results of the scientific analyses into the WSMPA borders and management zones.

At last year’s meeting, it was agreed that a five-year work plan for the Scientific Committee should be developed for consideration by the Scientific Committee in 2017 (SC-CAMLR-XXXV, paragraphs 13.8 to 13.20). It was agreed that the work should be led by the Chair of the Scientific Committee with input from the conveners of its working groups and that it should be made available for consideration by each working group prior to submission to the Scientific Committee.

This document represents the first stage in the development of the five-year work plan and draws on recommendations arising from SC-CAMLR-XXV and the 2016 Scientific Committee symposium (SC-CAMLR-XXXV/12). In particular, the plan has used the template of the five-year work plan of the ATCM CEP and considers a range of work ‘themes’ which arose from the SC symposium as priorities for the Scientific Committee. These broad themes are as follows:

• Target Stock- Assessments to estimate sustainable yield in established/assessed fisheries
• Target Stock-Development of management advice consistent with Article II for data-limited fisheries
• Ecosystem based management of Southern Ocean krill resources
• Minimisation of risks of change to the ecosystem by CCAMLR fisheries – Vertebrate by-catch and VME in CCAMLR fisheries
• Spatial management of impacts on the Antarctic ecosystem
• Data acquisition and management.

Within each theme, a range of tasks have been identified along with science topics to be considered in order to carry out the tasks. A timetable of work within each theme has then shown under which working group the tasks will fall. These tasks are based largely on table 1 of SC-CAMLR-XXXV along with consideration of discussion arising from SC-CAMLR-XXXIV/14.

It is intended that the final document will become a ‘living document’ that can be revised annually as the priorities of the SC develop and unforeseen issues that require action from the SC may arise. It is intended that the document will also be publically available in order to promote a greater public understanding of the priorities and work of the Scientific Committee.

Ukraine proposes a plan for scientific research in Statistical Subarea 88.1 for vessels SIMEIZ, KOREIZ, CALIPSO, MARIGOLDS based on the provisions of paragraph 2 of Conservation Measure 91-05. Studies are expected to be conducted in the Special Research Zone (SRZ)

Korean research fishing was conducted in Subarea 88.3 from 11 January 2017 to 7 March 2017 in 2016/17 fishing season. The total number of fishing days are 38 of 56 days stayed in the fishing grounds. The total catch of D. mawsoni was 118,220 kg with 4,132 individuals, and their CPUE recorded 0.21 kg/hook. 957 individuals of D. mawsoni were tagged and released. Tagging rate and tag overlap statistics in Subarea 88.3 were 5.04 and 88%, respectively. Length frequency of D. mawsoni had a single mode of 150 cm range. The maturity of D. mawsoni dominated in stage 2 with 84.6 % of female and 73.1% of male during the survey period. To get biological information of species in detail, otolith, stomach contents, gonad and muscle were collected from each individual of D. mawsoni. We also collected temperature and salinity using CTD at 12 stations.

The research fishing was conducted in Divisions 58.4.1 and 58.4.2 from 12 January 2017 to 14 March 2017 in 2016/17 fishing season. One additional national observer was on board to perform various scientific researches. The total catch of D. mawsoni was 153,084 kg with 4,360 individuals. The CPUE of D. mawsoni recorded 0.22 kg/hook. 805 individuals of D. mawsoni were tagged and released and additionally satellite archival tags were attached to 5 individuals of D. mawsoni. In Divisions 58.4.1 and 58.4.2, tagging rate with tag overlap statistics of D. mawsoni were 5.22 with 88% and 5.51 with 74%, respectively. Seven individuals of tagged D. mawsoni were recaptured. The research vessel, Kingstar has encountered unknown fishing gears during research fishing in SSRU G and E of the Division 58.4.1 and reported the information to the Secretariat. To get biological information of species, otolith, stomach contents, gonad and muscle were collected from each individual of D. mawsoni. Total 35 times of plankton sampling were conducted in the areas of Division 58.4.1 and 58.4.2. Two compact CTDs (Micro CAT, SBE37SMP) were used along with protective frames that would prevent the CTD connector from being damaged. Water temperature and salinity were collected from 33 data profiles during the survey in the areas of Division 58.4.1 and 58.4.2.

The third year research survey of Ukraine in subarea 48.2 by the fishing vessel SIMEIZ is finished. Ukraine proposes to continue survey in same boundary in same design for the next 2 year.

The assessment of toothfish in CCAMLR subarea 48.3 currently uses the first four years of tag recaptures post release as input data, whereas the assessment in subarea 48.4 uses all available recapture data (excluding in-year recaptures). A theoretical analysis of the use of data from double-tagged recaptures suggests that including recaptures from fish at liberty for long periods will introduce bias into the assessment. Sensitivity tests on both stocks show that this bias occurs in practice. Sensitivity tests on the 48.3 assessment show that this bias is not entirely explained by the effect of double tagging.

The existing bootstrap used in the assessment of icefish biomass in CCAMLR subarea 48.3 was compared to an alternative rescaled bootstrap to compare the performance of the methods. The differences between the method were small (less than 5%) except for slightly lower 5%iles in 2002 and 2004 in the rescaled bootstrap.