An integrated model was configured to estimate eighteen different subsets of 119 total parameters in alternative configurations of a model assessing the status and productivity of Antarctic krill (Euphausia superba, hereafter krill). We fixed the parameters that were not estimated in any given configuration at pre-specified values. The model was fitted to survey and fisheries data for krill in Subarea 48.1, a statistical reporting area used by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). The number of estimated parameters was gradually increased across model configurations. The numbers of parameters estimated in configurations that were able to obtain an invertible Hessian matrix ranged from 48 to 107. Groups of estimated parameters in each configuration were activated in seven sequential stages (the "phases") in a series of at least 20 replicate trials for each configuration. The parameter phases were assigned and reassigned randomly in each trial until an invertible Hessian matrix was obtained, or until 3,000 phase assignments had been completed for the replicate without obtaining an invertible Hessian. Model configurations were evaluated in terms of the total objective value, the maximum gradient, the proportion of replicate trials that found the minimum observed negative log-likelihood, and the number of iterations required in each trial series before obtaining an invertible Hessian matrix. Configurations that estimated more parameters fitted the data better, but the order in which the parameters were estimated became more important in finding the best fit as the numbers of estimated parameters increased. Phase-randomized replicates in configurations estimating many parameters were more likely to estimate values representing local minima than the lowest negative log-likelihood. The best observed estimates for the base configuration were obtained in about half of the replicates. Configurations estimating more parameters than the base configuration fitted the data better but either did not produce invertible Hessian matrices or had high maximum gradients. Diagnostics were applied to Markov chain Monte Carlo sampling in the best model of each configuration that obtained an invertible Hessian matrix to test for convergence to the equilibrium distribution.

The third year survey and observations of Dissostichus spp. in statistical subarea 48.2 on board the Ukrainian vessel SIMEIZ were conducted in accordance with the recommendations of the Scientific Committee and Commission. The third year survey design was slightly amended in comparison with the one of the second year and approved by WGs SAM, FSA and SC CCAMLR.  Obtained data will be used for the future biomass estimation of the target species and making decision for the future fishing on that fishing ground. 

The integrated assessment for Antarctic krill (Euphausia superba) in CCAMLR Subarea 48.1 has been under development since 2010. Progress on the model during this period was reported in a series of papers and presentations to WG-EMM, WG-FSA and WG-SAM from 2011 to 2016. The full text of the recommendations extracted from the CCAMLR Scientific Committee reports regarding the integrated krill assessment during that period is included as an Appendix to this document.

The purpose of this paper is to summarize the recommendations from CCAMLR Working Groups and the Scientific Committee that have been made to date along with a description of how the model has incorporated those suggestions, and to obtain advice from WG-SAM regarding whether the parameter estimation portion of the current model appears mature enough to use for representing the population/subpopulation represented by krill in Subarea 48.1, or, if not, what modifications or additions are required. This paper is focused on parameter estimation and does not include using the integrated model to make future projections to determine if candidate levels of harvest meet decision rules. The future projection components of the integrated krill model are undergoing revision following WG-SAM-2016.

In 2016, scientists from the USA and New Zealand undertook a collaborative initiative to deploy pop-off satellite archival (PSAT) tags on Antarctic toothfish (Dissostichus mawsoni) on the southern shelf (SSRUs 88.1M,J,L) and northern seamount (SSRUs 88.1B,C) areas of the Ross Sea region. The objectives  were to characterize movement and habitat preferences, compare two different commercially available types of PSAT tags, and to develop methods to support research and monitoring of the Ross Sea region Marine Protected Area. All fish were tagged as part of research longline efforts under CM 24-01 after the 2015/16 toothfish fishing season had ended. A total of 10 PSAT tags from two manufacturers were released on the southern Ross Sea shelf in the austral summer, and 5 PSAT tags were released on the northern seamounts in the austral winter, for a total of 15 PSAT releases. Of the 10 PSAT releases in the southern Ross Sea, data from two tags were reported via Argos (one with full data, one with partial). On the northern seamounts, two of 3 PSAT tags scheduled to pop-off on February 1, 2017 reached their housing crush depth (1800 m) shortly after they were released. Although some useful data was collected during this experiment, data recovery in general was poor. As this is a developing technology proposed to be implemented by a number of Members, we suggest that additional work, including product development, is urgently needed to develop best practice guidance for tagging toothfish with PSAT tags.

The indices of exploratory toothfish fishery in the Subareas 881 and 88.2   for the period of 2010-2016 are considered. Taking into account the different number of hooks at longlines sets used at the fishery, the catch indices were normalized to 1000 hooks.  The effect of the gear types (autoline, spanish, trotline) on the observed spatial-temporal variability of CPUE toothfish   (kg/1000 hooks), by-catch CPUE (kg/1000 hooks) and normalized target catch ratio is considered. Particular attention was focused to the analysis of the length-species compositions of catch by years and SSRU while using different types of longlines. Our results  show that the gear type  is the most important factor that must be taken into account both during the longline fishery data analysis and the research programs planning.

Closed mostly within the Weddell Sea Subarea 48.5 is one of the closed data-poor CCAMLR subareas, where stock assessment should be carried out. In spite of hard ice conditions at most part of the Sea during mostly all the year, this large water area is very similar to the Ross Sea. This similarity could be found in geographical location, bathymetric profile, currents system and follows from results of the first and the second stage of this program. It highlights the Weddell Sea as one of the most promising area for exploratory fishery of Dissostichus sp. However, fishery in Subarea 48.5 is closed on the basis data on stock assessment absence. The main objective of the present program is collecting data for reliable stock assessment and following estimation of precautionary limits in accordance with CCAMLR decision rules. The program contains schedule and research program of the third stage of the Russian multi-year research program in the Weddell Sea that is prospected for 3-5 years. Detailed plan of fishing operations, data collecting and analysis will be provided for the Scientific Committee and Commission consideration.

Russian Federation is going to continue investigation for toothfish in Ross Sea. The previous Russian program was undertaken in the Subarea 88.2 in 2010-2012. This paper presents the   research program in the frame of the research and monitoring associated with the RSRMPA.

Russian research program have objectives to investigate the life-cycle, distribution and movement, biological parameters and stock structure of Dissostichus species in the eastern part of the Ross Sea over shelf and continental slope within the Subarea 88.2 A.  The tagging toothfish and recapture tagged fishes   to be in focus.  The study area covered by proposed investigations is located in the Special Research Zone of the RSRMPA. Proposals include the priority elements for scientific research and monitoring associated with the Ross Sea region marine protected area. 

The research program shall be conducted in the Special Research Zone during 2017-2027 or the first reference period for existence of the RSRMPA.   This program provides possibility   for collaborative investigations in the Special Research Zone by Russian vessel and vessels from other CCAMLR country-members. Implementation of this program can be started in the forthcoming season 2017/18.    

Exploratory fishing in Division 58.4.3.a is conducted by two vessels using longlines: “Shinsei Maru No. 3” (Japan) and the “Saint André” (France), since 2012. Precautionary management arrangements are in place in Division 58.4.3.a (Conservation Measures 41-05 and 41-11), while data are collected to provide a robust stock assessment and catch limits. A research plan jointly written by France and Japan has been submitted to WG-SAM-17, which included research objectives, methods and milestones in accordance with Conservation Measure 41-06 and associated measures. The main objective of this paper is to provide an overview of the data collected in Division 58.4.3a up to the CCAMLR fishing season 2016/17.