Catch and effort data recorded by all vessels were analyzed using the latest CCAMLR C2 and observer data.
The stock size estimates for research blocks were revised following advice in the last WG-SAM meeting. We tentatively recalculated a sample size of Dissostichus spp in each block in such a way that the numbers of tag recoveries in the 2016 season shows an approximately 0.3 of coefficient variance of biomass estimate from the bootstrapped procedure, under the condition that the exploitation rate (sample size / estimated stock size) would not exceed 3.5%. The tentatively estimated sample sizes turned out to be larger in many blocks and smaller in a few blocks over the data poor-fisheries. 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 conduct the current research operation for at least 3 years with the same sample size as decided at the last CCAMLR meeting for the current research blocks, in order to promote successful stock assessment.
We tentatively examined the degree of coverage of the austral summer sea-ice during past 10 years in the current research blocks and an additional research block (486e in SSRUs B and C) which Japan and South Africa proposed in the last WG-SAM meeting. The sea-ice condition during the summer season was generally favorable for operations for the research blocks. Based on this examination, 486e block appears to be a promising research block and hence we propose the addition of the research block 486e, where Shinsei-maru No.3 released a total of 587 tagged D. mawsoni in 2011, in order to maximize the use of tagged fish.
We propose the extension of the east boundary of research block 486d from the current 13°E to 15°E to examine whether the fish migration could be active in this continental-shelf block.
The separation rule was one of the major inconveniences for successful research, as it may excessively limit the available area for research hauls. For this reason, we propose the mitigation rule that 50% of lines are required to be separated by not less than 3 n miles from each other but the rest of lines can be set freely between the separated lines. In this way, over-concentration of catch and effort can be avoided while reducing the inconveniences for operation.
Similarly, strict application of the move-on rule could compromise success in the research. We propose the relaxation of rule by increasing the current trigger level of 1 500 kg for the catch of Macrourus spp. in two 10-day periods provided in the paragraph 6 of CM33-03 to 2 000 kg.