Research plan for the exploratory fisheries for Dissostichus spp. in Subarea 48.6 in 2014/15

Historical catch and effort data recorded by all effective vessels were analyzed using the latest CCAMLR C2 and observer data toward the development of research plan for the 2014/15 exploratory fishery of toothfish in Subarea 48.6.

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 effective data on tagging experiment and appropriate reference areas for the CPUE method recommended at the last WG-FSA meeting. The stock size estimate using the Petersen estimator was similar to that using the CPUE method 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 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 WG-FSA meeting last year, 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 the current fishing season, the Japanese vessel attempted to conduct survey in two blocks, 486_4 and 486_5, along the ice shelf. However, any of research blocks, their buffer zones and extended buffer zones prescribed in the current CM were not accessible due to anomalously bad ice conditions, and accordingly she could not set any research lines. From the perspective to promote efficient and robust research for establishment of stock assessment in these ice shelf blocks, it seems that the current arrangement to cope with bad sea ice condition is insufficient and that some more flexibility is needed for such exceptional events. In this regard, we would like to propose following mitigations; i) if both the buffer zone and the extended buffer zone are inaccessible due to heavy sea ice, a vessel shall notify the Secretariat, and may attempt to set research lines in the nearest fishable area reasonably close to the original research block. In such a case, the catch will be counted against the catch limit of the original research block; and ii) when a vessel attempting to survey cannot find nearest fishable area reasonably close to the original research block under adverse ice conditions, the whole catch limit in the research blocks for a fishing season may be carried over to the following season. The carried-over catch limit will be effective for only following one season. These mitigations would contribute to maximize the use of existing tags, and may provide important information on movement of fish in ice shelf zones.