We provide extensive diagnostic plots for the 2017 models R1 and R3 for Antarctic toothfish in the Ross Sea as recommended by WG-SAM-15 (2015). The stock assessment rationale and models as well as their main diagnostics are described in Mormede (2017). The CASAL files for the assessment models were provided to the CCAMLR Secretariat as a zip file.

In this paper we present the results for first inputs, model R1 and then model R3. The diagnostic plots cover input data, MPD and MCMC outputs. Key tables are given in Mormede et al. (2017) including process error weightings and the MPD objective function components.

We provide a summary of the mark-recapture data inputs to the 2017 Ross Sea region stock assessment.

A total of 44 827 Antarctic toothfish have been released and 2473 recaptured, and 1 191 Patagonian toothfish released and 103 recaptured since 2001. Effective tagging survival and tag detection rates for each vessel were calculated. In the last few years the effective tagging survival is estimated at about 65% and the effective tag detection rate at about 85%.

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

The research of Dissostichus in Subarea 88.3 carried out by Chile in 1998, New Zealand in 2005, Russia in 2011 and 2012 and the Republic of Korea in 2016. It was noted that no tagged fishes were recaptured during the previous research activities. Studies are planned to be conducted from January to April, as ice conditions permit. It is planned that the number of longline sets will be 60 in four reserch blocks. It is planned to complete the study for Dissostichus spp. in Subarea 88.3 within 3 years.

Ukraine proposes to conduct survey in three research blocks in Division 58.4.2 during the season 2017/18. 

Ukraine proposes to carry out a scientific survey of Dissostichus spp. by bottom longline in the eastern part of Subarea 48.1.

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 for the next 2 year.

The Scientific Committee has previously considered results from the Krill-Predator-Fishery Model to assess the risks of distributing catch limits for krill among small-scale management units (SSMUs) in Subareas 48.1, 48.2, and 48.3. Here we describe a method to update the parameterizations of this model and conduct comparable risk assessments at smaller spatial scales. We use the method to assess some of the risks associated with two marine protected area (MPA) scenarios in Planning Domain 1, one representing the MPA proposed by Argentina and Chile. We conclude that the MPA proposed by Argentina and Chile can, if desired, be improved by changing the sizes of the coastal buffers that define the General Protection Zones around the South Shetland and South Orkney Islands. We also conclude that the proposed MPA seems likely to satisfy multiple objectives simultaneously.

In order to explore aspects related to the structure of population units and habitat use of Dissostichus spp. within CCAMLR Subarea 48.2, the elemental composition of nuclear and marginal sections of 10 otoliths from adults of D. eleginoides and 20 otoliths from adults of D. mawsoni from samples of otoliths collected during the first season of the research carried out by the Chilean Delegation in Subarea 48.2 of CCAMLR during the 2015/16 fishing season. The otoliths through laser ablation and mass spectrometry with inductively coupled plasma (LA-ICPMS) was sampled and analyzed. Eleven elements were selected for analysis: 7Li, 23Na, 24Mg, 52Cr, 55Mn, 59Co, 60Ni, 63Cu, 86Sr, 120Sn y 138Ba, using their relative concentration to Ca. The univariate and multivariate analysis of the elemental composition of the nuclear zone showed significant differences between species, suggesting physiological differences and/or segregation of nursery habitats between them. The analysis of the elemental composition of the marginal sections presented univariate differences but not multivariate differences between species, suggesting a higher degree of overlap between the habitats used by the adults of each one of them. The differences found between nuclear and marginal sections among the species were consistent with the change of habitats described in the literature for each one of them. The comparison of our results with previous reports of elemental composition showed similarity between D. eleginoides samples of this study and the samples previously collected in South Georgia and Shag Rocks. In the case of D. mawsoni, the results clear differ from the results available for the Ross Sea, suggesting the existence of different demographic and/or evolutionary units in each area.

This paper outlines the specific research objectives and plan to achieve them for the second year of an agreed 3-year longline survey, in the wider context of connecting the recently undertaken surveys in Subarea 48.2 with the established fishery in Subarea 48.4. The overall research objectives include determining population connectivity between these Subareas, improving understanding of Dissostichus sp population structures in this region, and improving available data on bathymetry and associated distributions of benthic bycatch species. This paper reiterates the key points of WG-SAM-17/34, updates information on tag-recapture data from the first year of the survey, and includes a three-year data collection and two-year data analysis plan leading towards the development of a stock hypothesis for the eastern regions of 48.2 and southern regions of 48.4.