CCAMLR

Comparative data on size-age composition and growth of Antarctic toothfish D. mawsoni in the Pacific (SSRUs 88.1, 88.2) and Atlantic (SSRU 48.5) Antarctic areas in 2005-2014 seasons are described.

Stock assessment of the Antarctic toothfish in the Subarea 88.2 H using Peterson method is presented in this paper. Calculated stock value of the Antarctic toothfish in the Subarea 88.2 H is 20649 t with 95% confidence interval ranging from 12475t to 39901t. In 2014-2015 values of potential catch with incomplete taking of 3%, 5% and 10% were determined as 619t, 1032t and 2064 t respectively.

Russian Federation intends to continue research in Subarea 88.2 that began in 2010-2012. The main objectives are studying of toothfish migration from SSRU 88.1 K to Subarea 88.2 A. The survey program was improved in accordance with recommendations of WG-SAM-2014 and intercessional work with CCAMLR country-members in order to unify the data collection plan and methods during the proposing mutli-member research program in the Ross Sea – Subarea 88.2.

Suggestion and comments on changes in basic documents for scientific observers (logbook, cruise report etc.) produced during the inter-session SISO work are presented in the paper. Position of the Russian Federation on development of centralized preparation and accreditation scheme for scientific observers and CCAMLR member countries is amplified here.

Available data on the by-catch of Rajiformes was extracted from the CCAMLR database. These records included commercial catch data as well as observer data. Spatial distribution and biological data was broadly consistent with current literature although there were indications of larger spatial ranges for some species.  The data collected as part of CCAMLR fisheries represents a very substantial repository of information on Southern Ocean Rajiformes; realising the full potential of this data will require a review of the consistency and accuracy of identification of taxa and this might be a useful for a future focus topic in the SISO.

In 2013, POKER Biomass survey was undertaken at Kerguelen Islands (Division 58.5.1) to collect information of all the fish species including the mackerel icefish, Champsocephalus gunnari. Data from this random stratified trawl survey, added to the previous results of 2006 and 2010, was used for a short term assessment of C. gunnari on Kerguelen EEZ. The standard CCAMLR methods were used to provide potential yields, a catch limit of 840 t is recommended for 2014 and 580 t for 2015.
 

Depredation is a human-wildlife conflict over resource which often includes a combination of socio-economical, ecological and conservation issues. However, estimating the amount of depredated resource can be especially challenging when depredation occurs on fish in the marine environment. This is the case for killer whales (Orcinus orca) and sperm whales (Physeter macrocephalus) depredation on the demersal Patagonian toothfish (Dissostichus eleginoides) longline fishery operating within the Crozet Islands EEZ (southern Indian Ocean). As the two species remove the entire fish from the hooks whether they depredate longline hooks separately or simultaneously, this study aimed at providing two indirect methods of assessment of depredated biomass over a 11-year period (from 2003 to 2013), both accounting for spatial variations of depredation levels. In the first method, we used fishing data from 6 525 longline sets to calculate the difference between Catch Per Unit Effort (CPUE) of non-depredated and depredated hooks. From this difference and using the fishing effort (number of hooks), we estimated that 575 ± 35 t and 739 ± 87 t of Patagonian toothfish were respectively depredated by killer whales and sperm whales when the two species occurred separately, and 1 679 ± 74 t were depredated from 2003 to 2013 when the two species co-occurred around vessels. The second method was new in a way that we used the differences of proportion of by-catch species (i.e. grenadiers – Macrourus sp.) between non-depredated and depredated longline sets to estimate the number of depredated Patagonian toothfish. This approach, which can only be implemented when a sufficient level of bycatch species occurs,  provides strong support to the CPUE method. From these two methods, depredation rates were estimated to range from 27,3% to 29.1% % of the total capture (landed + depredated), that is one of the highest among all similar depredation situations reported elsewhere in the world. In addition to providing methodology insights that could be used in other areas with such depredation issues, these findings emphasize the critical importance for fishery managers and researcher to account for depredation when assessing fish stocks, fishery economy and/or conservation of odontocetes.

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 Weddell Sea during most time of the year, this large water area is very similar with the Ross Sea. This similarity, which could be found in geographical location, bathymetric profile, currents system and follows from results of the first and the second stage of this program, highlight 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 Federation multi-year research program in the Weddell Sea that are prospected for 5 years. Detailed plan of fishing operations, collecting and analysis of data will be provided for the Scientific Committee and Commission consideration.