CCAMLR

In this document, we revised stock status assessments of D. eleginoides in research blocks 5843a_1 using CPUE analogy method, Petersen method and CASAL model, although the tagging data of current season has not been validated and not used for the present analysis. We used updated reference area size for the CPUE method. Detailed results using CASAL models in the research block are described in a separated document.

The estimated stock size in the block was 2 393, 394 and 647 tonnes in CPUE analogy method, Petersen method and R.0.1 model (vulnerable biomass in 2013), respectively. Predicted number of tag recaptures from the estimated stock sizes using the Petersen and CASAL methods was consistent with the observed number in 2013/14 season. However, these estimators were based on tags released and recaptured only at the western end of the block, as pointed out at the last WG-FSA meeting (paragraph 6.66 of SC-CAMLR-XXXII, ANNEX 6, 2013).

As for the recommendation on east and west separation of research block for management due to considerable difference of catch rates between the locations and concentration of effort in the west during the last WG-SAM meeting (para. 3.37 of WG-SAM-2014 report), we investigated the historical catch rates in relation to locations and depths by vessels. As a result, we found no significant differences of catch rates between east and west areas for principal vessels except one vessel which is mainly attributed to the concentration of effort in the west and the large difference of catch rates between the east and west during the latest seasons. Thus we consider that the above mentioned differences between the east and west areas were related to one specific vessel and not a general matter. As a sufficient number of sets have been conducted in the east area, it should be recognized that the area has finished its prospecting phase. Therefore, we believe that we do not need to separate the management in the area provided appropriate spread of effort over the bank for the vessel is ensured.

We propose to set the sample size at current 32 tonnes for at least 3 years, which is likely to result in sufficient tag recaptures to substantially refine the stock assessment, as well as constituting a sufficiently low risk harvest rate as suggested at the last WG-FSA meeting.

The stock size for a research block (5842_1) was estimated by the CPUE x seabed analogy method using updated CCAMLR C2 data and reference area sizes.

As we proposed at the last WG-SAM meeting, since we have yet to obtain enough evidence to estimate plausible stock size, and accordingly have yet to estimate appropriate catch limit, we propose to continue the current research operation for at least 3 years with the same sample size as decided at the last CCAMLR meeting in the current research block, in order to promote successful stock assessment. On the other hand, we preliminarily estimated a sample size for 2014/15 using the CPUE analogy method for block 5842_1. The result of calculation was consistent with the current sample size.

In addition, we propose to allow flexibility in cases of research operations under extraordinary adverse ice-conditions, as detailed in in the research plans for Subarea 48.6 in WG-SAM-14/01 (2014) and WG-FSA-14/XX (2014).

The stock sizes for five research blocks (5841_1, 5841_2, 5841_3, 5841_4 and 5841_5) were estimated by the Petersen estimator and the CPUE x seabed analogy method using updated CCAMLR C2 data and reference area sizes. The stock size using the Petersen estimator was generally different from that using the CPUE method in each block.

As we proposed at the last WG-SAM meeting, since we have yet to obtain enough evidence to estimate plausible stock size, and accordingly have yet to estimate appropriate catch limit, we propose to continue the current research operation for at least 3 years with the same sample size as decided at the last CCAMLR meeting in the current research blocks, in order to promote successful stock assessment. On the other hand, we preliminarily estimated sample sizes for 2014/15 using the CPUE analogy method for each block except for block 5841_5 where Petersen method was applied following the procedure recommended at the last WG-FSA meeting. The results of calculations were generally consistent with the current sample sizes.

In addition, we propose to allow flexibility (i.e. carried-over and buffer zone) in cases of research operations under extraordinary adverse ice-conditions, as detailed in in the research plans for Subarea 48.6 in WG-SAM-14/01 (2014) and WG-FSA-14/XX (2014).

The stock sizes for five research blocks (486_1, 486_2, 486_3, 486_4 and 486_5) were estimated by the Petersen estimator and the CPUE x seabed analogy method using updated CCAMLR C2 data and reference area sizes. The stock size estimate using the Petersen estimator was similar to that using the CPUE method (using Division 88.2H as a reference area) for Dissostichus mawsoni in block 486_2. However, the estimates using the Petersen estimator were different from those using the CPUE method in other blocks where the Petersen estimator was applicable. Predicted numbers of tag recaptures from the estimated stock sizes using the both Petersen and CPUE methods (using Division 88.2H as a reference area) were relatively consistent with the observed numbers for D. mawsoni in the block 486_2 for 2012/13 and 2013/14 seasons. However the predicted and observed numbers using either method were inconsistent for Dissostichus spp. in other blocks.

As we proposed at the last WG-SAM meeting, since we have yet to obtain enough evidence to estimate plausible stock size, and accordingly have yet to estimate appropriate catch limit, we propose to continue the current research operation for at least 3 years with the same sample size as decided at the last CCAMLR meeting in the current research blocks except in block 486_3, in order to promote successful stock assessment. On the other hand, we preliminarily estimated sample sizes for 2014/15 using the CPUE analogy method for Dissostichus spp. in all blocks generally following the procedure recommended at the last WG-FSA meeting. The results of calculations were generally consistent with the current sample sizes, except for D. eleginoides in blocks 486_1&2.

In research block 486_3, the number of observed recaptures, which was significantly lower than those predicted, can be a result of limited number of hauls (only 13 and 14 hauls in 2013 and 2014, respectively) associated with the small catch limit. Regarding relatively high CPUE in the area, we propose to increase the catch limit from current 50 tonnes to 100 tonnes under the exploitation rate of 3 % in order for succeeding in the tagging experiment.

In addition, we propose to allow flexibility (i.e. carried-over and buffer zone) in cases of research operations under extraordinary adverse ice-conditions, as detailed in WG-SAM-14/01 (2014).

Mitigating the adverse affects of commercial fishing on the environment is an integral responsibility of fisheries globally.  Efforts to reduce bycatch, to exploit previously unfavourable species and to carry out research on associated organisms have increased with time but charismatic megafauna tend to gain priority, despite their numbers being relatively low compared to fish bycatch species.  The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) is widely recognized for its thorough and effective management of Southern Ocean toothfish fisheries, especially in eliminating incidental seabird mortality, but comparatively little research has been applied to the thousands of fish caught as bycatch annually.  Fish bycatch mitigation controls in toothfish fisheries have seen a relatively recent evolution through CCAMLR’s conservation measures but their effectiveness has not been thoroughly investigated. This study explores trends in fish bycatch of exploratory fisheries for toothfish within the CCAMRL Convention Area, from 2006–2013, relating observations to CCAMLR’s conservation measures.  We found a significant reduction in bycatch landings by weight and number of individuals across years, despite no significant reduction in fishing effort probably linked to changes in landings of skates.  Bycatch by weight formed 6.7% of total catch per year, however the number of individuals landed was at times double that of toothfish. Gear type comparisons indicate that autolines catch a greater diversity of bycatch species than Spanish lines and trotlines.

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.