Exploratory fishing for toothfish (Dissostichus mawsoni) in East Antarctica (Divisions 58.4.1 and 58.4.2) began in 2003. Robust stock assessments and catch limits according to CCAMLR decision rules remain to be determined for these Divisions. WG-FSA-16/29 outlined the first multi-member toothfish exploratory fishery research plan up to 2017/18 for East Antarctica, which the Scientific Committee agreed was appropriate to achieve the research objectives (SC-CAMLR 2016, para. 3.244). Subsequent research progress including the evaluation of standard approaches to identify precautionary catch limits (WG-FSA-17 para. 4.28-4.38) and bycatch mitigation (Maschette et al. 2017), suggests a low risk profile for this fishery. Furthermore, examination of bycatch data and underwater video footage have not led to the identification of vulnerable marine ecosystem (VME) indicator species (Maschette et al. 2017, Eléaume et al. 2018). Here, we update the research plan for 2018/19 to 2021/22 (WG-FSA-18/59), in accordance with ANNEX 24-01/A, Format 2. This plan has been designed as a 4-year plan, based on the low risk profile of this fishery and to allow more time for review by Working Groups of major reporting and review years in non-stock-assessment years.

Compared to last year (WG-FSA-18/59), this research plan has been updated with 2019/20 operating details, the inclusion of modelling work under Objective 2, and a re-ordering of milestones under Objective 4.

Based on a recommendation by WG-SAM-19, inter-sessional discussions have been held between the existing co-proponent and the Russian Federation, but no agreement has been reached so far. Should the Russian Federation agree to become a co-proponent of this proposal, Russian research contributions could be integrated in an additional research objective as shown in the example below (marked as track changes in this document). One option would be to evaluate the impact of survey design on estimates of toothfish biomass and biological parameters.

Russian research of craboids (Anomura, Decapoda) in the Antarctic Pacific (Subareas 88.2 and 88.3) were carried out by the  vessel “Antarctic Wolf” in March 2019 in full compliance with the Russian program (WGSAM-18/06; WGFSA-18/32 Rev.1) and recommendations of the Scientific Committee (SC-CAMLR –XXXVII, paragraph 4.3 (i-viii)). Pot catches was presented by craboid Paralomis birstaini and Antarctic King crab Neolithodes yaldwini. Detailed analysis of obtained data is shown.

Fishing for Patagonian toothfish (Dissostichus eleginoides) has been carried out around South Georgia continually for more than 40 years, including more than 25 years under CCAMLR management.

This paper reviews the long-term decline in the size structure of Patagonian toothfish (Dissostichus eleginoides) observed in longline catches taken in the South Georgia Area (FAO Area 48.3). We note that from the start of the 2000s until now, longline fishing in the South Georgia area has targeted immature fish smaller than 100 cm. The issue of non-rational use of the Patagonian toothfish stock in Subarea 48.3 is examined.

During Austral summer 2018-19, four Ukrainian longliners continued the opportunistic collection of the mesozooplankton in the Pacific and Atlantic sectors of the Southern Ocean. Zooplankton were collected onboard four Ukrainian longliners: CALIPSO, KOREIZ, MARIGOLDS and SIMEIZ

This document summarizes oceanological data for the season 2018-2019 from Ukrainian longline fishery ships, worked in the CCAMLR area. Information about vertical distribution of temperature, bottom temperature variability, spatial temperature changes, inter-annual temperature variability, water masses and relationship of temperature with catches of toothfish in Weddell, Ross and Amundsen Seas are presented. Some conclusions were made why Ross Sea is characterized by the highest catches of toothfish per effort.

The Antarctic toothfish, Dissostichus mawsoni, serves as valuable fishery resources around the Antarctic Continent since 1997, managed solely by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR). Although defining genetic or stock structure of populations is crucial for improving fishery management of this species, the number of populations or stocks of D. mawsoni in this Antarctic region remains currently unknown. In the present study, we assess the population genetic and phylogeographic structure of the Antarctic toothfish populations across 11 geographic localities from the two main Subareas 88 and 58, based on a combined analysis of mitochondrial DNA (mtDNA) cytochrome oxidase I (COI) sequences and four nuclear microsatellite loci. MtDNA revealed a very low level of polymorphism (h=0.109, π=0.0002) with only eight COI haplotypes in 213 individuals, connected only by 1-3 mutational steps. Nonetheless, microsatellites showed much higher variation with allelic richness (AR) values of 5.8 to 6.7 within populations. Four of six populations showed a genetic signal of inbreeding, despite no sign of population bottlenecks detected. Population structure analyses of microsatellites suggest that the sampled 88 Subarea populations are likely to comprise a well-admixed single gene pool (one genetic stock). However, given weak but significant microsatellite differentiation found between some populations, the possibility of existence of multiple stocks could not be fully excluded. To clarify this, further study with additional polymorphic markers (such as microsatellites) using more samples from other areas, particularly the 58 Subarea will greatly help to determine the population or stock structure of D. mawsoni in this region. The findings of this study will inform conservation efforts on the stock (unit) management for this valuable fishery resource.

Antarctic toothfish, Dissostichus mawsoni is the ecologically important Nototheniidae, which is native to the Southern Ocean. Although it plays an important role in the Antarctic ecosystem, the ecology of D. mawsoni is still fragmental mainly due to the limited accessibility for the sample collection. Diet study provides the basic information of feeding relationship among the different trophic levels. Since 2016, we have been studying the stomach contents of D. mawsoni by the combination of morphological analysis and the molecular identification using next generation sequencing (NGS) platform. We here report about the prey item of D. mawsoni collected from the two research areas (58 and 88) from 2016 to 2018 using metabarcoding analysis of 1,329 its stomach contents. Total 71 haplotypes (8 orders, 17 families, and 32 genera) were identified by COI universal primers, which included 60 fish and 8 cephalopod species. As reported previously, proportions of fish taxa occupied 98 % indicating the major prey items of D. mawsoni are fish species. Higher prey species numbers were obtained by the metabarcoding analysis compared to the morphological analysis especially it was useful to identify the species with similar morphological characters including fish in Family Channichthyidae. Among the prey objects, two fish species, Macrourus whitsoni and Chionobathyscus dewitti were the most important prey items of D. mawsoni and ratio between two species appear to be related to the size of D. mawsoni. Many of fish taxa in the stomach of D. mawsoni showed the multiple haplotypes by NGS analysis suggesting that those haplotypes would provide more useful data to understand the ecology of D. mawsoni. However, the length of the amplified PCR products (~600 bp) in this study may not have enough size for the clear analysis of haplotypes. Further study should be made to obtain the longer DNA marker for the identification of each species and its haplotypes. PacBio sequencing system would be the good candidate for the purpose, which can produce the much longer reads than the MiSeq sequencing system. 

Otolith chemical analysis is one of important and useful approaches to reveal the stock structure and connectivity of Dissostichus mawsoni in the Southern Ocean. Recalling the suggestion from WG-FSA 2018 about the international collaboration on otolith microchemistry of D. mawsoi, this progress report summarized the update of this work. The result indicated that the heterogeneity in stock structure of D. mawsoni occurs between Subareas 88.1 and 48.6. Samples from Subareas 48.4, 48.5, Subarea 88.3, Divisions 58.4.1, 58.4.2 and 58.4.3, and SPRFMO area are encouraged to be collected and included into this collaborative project.

Fourier shape analysis was used to study the morphology of sagittal otoliths of 383 Dissostichus mawsoni from 3 Subareas using two statistical methods. Stepwise discriminant analysis showed a classification accuracy of 73.19%. Principal component analysis revealed the accumulated contribution rate of 29 principal components was 72.45%. These findings demonstrate that Fourier analysis of otolith morphology cannot distinguish the stock populations of D. mawsoni between Subareas 48.1, 48.6 and 88.1.