CCAMLR

We propose to test three hypotheses to describe the reproductive ecology of Antarctic toothfish (Dissostichus mawsoni):

1) Antarctic toothfish eggs are buoyant and accumulate under sea ice. If true, this would retain eggs near the spawning locations under the vast sea ice extent and once broken up in the spring, may provide access to a productive pagophilic ecosystem for feeding as well as a transport mechanism for subsequent advection patterns, all of which could be impacted by climate change. This would have implications on the understanding where recruiting fish originate and how those patterns may be influenced by changes in sea ice or circulation patterns that affect observed recruitment patterns.

2) Antarctic toothfish spawn throughout the Pacific Antarctic fracture zone. Evidence to date only exists from the west of the region (SSRU 88.1B), yet adult Antarctic toothfish are found much further east and north of the CCAMLR Convention area, which is bounded by latitude 60°S. Obtaining a better understanding of the location and movement of adult spawning toothfish has direct implications on the understanding of those parts of the adult stock that contribute to recruitment, and hence the productivity of the stock assumed in the stock assessment.

3) Biological characteristics of the northern spawning population change as younger, fatter, female fish move to the north for spawning during winter. Evidence to date found no change in these characteristics in June, suggesting sampling later in the spawning season is needed.

We propose to conduct a scientific survey during the austral winter in the northern Ross Sea region to test these hypotheses. The longline and plankton survey is designed to cover key gaps in the knowledge of the life cycle of Antarctic toothfish in the Ross Sea by collecting biological samples from a range of locations in the northern regions of Subarea 88.1 and 88.2 and begin in September 2019. The survey will be coordinated with a corresponding survey targeting Antarctic toothfish spawning dynamics in the southern area of the South Pacific Regional Fisheries Management Organisation (SPRFMO) area at a similar time.

This paper outlines the specific research objectives and plan to achieve them for the third 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 plan 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.

Ukraine proposes to continue survey in the Subarea 48.2 in same boundary for the fifth year of research.

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 2017 and 2018. It was noted that no tagged fishes were recaptured during the previous research activities. Studies are planned to be conducted from January to March, 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 carry out a scientific survey of Dissostichus spp. by bottom longline in the eastern part of Subarea 48.1.

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 Ross Sea region marine protected area.

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 is located in the Special Research Zone of the RSRMPA. Proposals include the priority elements of the research and monitoring plan for the Ross Sea region marine protected area. 

The research program shall be conducted in the Special Research Zone during 2018 - 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 vessels and vessel from other CCAMLR country-members.

Russian program provides proposals to study the species composition, biology, life cycle, distribution and structure of craboids stock (Anomura, Decapoda)  and  assess their resource potential in the Bellingshausen Sea (Subarea 88.3) and Amundsen Sea (Subarea 88.2).

The scientific survey was conducted by the Greenstar (KOR) in the research block 883_3–883_5. Due to extreme ice conditions covering the southern part of 88.3, the Janas (NZL) was not able to conduct its part of the survey. The total catch of D. mawsoni was 38,856 kg comprised of 1,380 individuals. The CPUE for Dissostichus mawsoni indicated regional differences among the research blocks. While CPUE in blocks 883_3 and 883_4 showed similar values of 0.1369 and 0.1466 kg/hook, research block 883_5 was extremely low showing 0.0273 kg/hook. Tagging rate and tag overlap in Subarea 88.3 were 5.2 fish per tonne and 72%. The length frequency of D. mawsoni exhibited a bimodal distribution with modes near 70 cm and 150cm. Female maturity stage showed a regional pattern, with the stage 2 accounting for 47.8%, 28.1%, and 25.6% in the areas of 883_3, 883_4, and 883_5, respectively. To get biological information of D. mawsoni, otolith, stomach contents, gonad and muscle were collected. Water temperature and salinity were measured at 6 locations during the survey in Subarea 88.3. Notification of research for the agreed 2018-19 fixed-effort survey as detailed in WG-FSA-17/40 is included with thesame catch limit of 235 t as in 2017-18.

Japan and France propose a plan to continue investigate the populations of Patagonian toothfish (Dissostichus eleginoides) in the Division 58.4.4b during the next fishing season (2018/19) from 2017/18 onwards, using standardized longline gear, and established tagging techniques. The proposed research is relevant and take into account issues raised by the Scientific Committee (SC-CAMLR-XXXIII, paragraph 3.208), which requested that research activities be coordinated between France and Japan so that selectivity and catch rates can be standardized across the vessels and impacts of depredation be minimized.

Additional outcomes of the research relate to documenting the degree of depredation, tagging toothfish for biomass estimation and for stock linkage studies, and collecting information on distribution, relative abundance, and life history of bycatch species.

The plan represents a continuation of previous surveys by Japan and France, without significant change from the previous research activities.