Japan and France have revised the next season’s (2016/17) research plan in research blocks 58.4.4b_1 and 58.4.4b_2 using the latest CCAMLR C2 and Observer data, following several advices during WG-SAM meeting in 2016.
We have used extracted data provided by CCAMLR Secretariat in this late August for the current analysis, but not used the cleaning data provided by them in this early September due to tight schedule for the submission.
The estimated median stock size in block 58.4.4b_1 and 58.4.4b_2 was 776, and 583 tonnes, respectively, in Chapman estimator considering tags released in the last three years as effective for the calculation following the recommendation in the last WG-SAM meeting. The estimated median stock size in block 58.4.4b_1 and 58.4.4b_2 was 465 and 507 tonnes, respectively, in CPUE analogy method (reference area: HIMI) using the relevant information of reference area (recent median CPUE, estimated biomass and updated area size) recommended in the last WG-SAM meeting.
The geographical distribution of different size groups shows that small fish <60cm mainly occur in the shallow area in SSRU B. It is suggested that some juveniles in SSRU B migrate to other SSRUs and become important resources for whole SSRUs, although no migration has been observed between SSRUs to date.
Predicted numbers of tag recaptures from the estimated stock sizes using both Chapman and CPUE analogy methods were generally inconsistent with the observed numbers for each block, but the numbers using Chapman were generally closer to the observed ones for both blocks.
We propose to continue the current research operation for the next fishing season with the same survey design and total sample size of 60 tonnes in order to further strengthen the stock assessments in the area. On the other hand, Japan will examine the change of survey design from 2017/18 season taking into account change of CCAMLR's regulatory framework and make a brief presentation about this issue during the WG-FSA meeting.