A method for spreading the risk of localised effects of catches of Antarctic krill up to the trigger level, during the development of stage 2 of feedback management

Conservation Measure 51-07 provides an interim distribution of the trigger level in the fishery for Euphausia superba in Statistical Subareas 48.1, 48.2, 48.3 and 48.4.  It was established because the Commission, in the preambular paragraphs to that measure, recognised that localised catches up to the trigger level may affect krill predators.  They wished to establish a spatial distribution of the trigger level that ensured that krill predators “would not be inadvertently and disproportionately affected by fishing activity”.  CM 51-07 is to be “reviewed in 2016 with the intent of ensuring the implementation of Article II of the Convention, taking into account the resource requirements of land-based predators.”  In this paper, we build on previous investigations to distribute the fishery in Area 48 to develop a framework for the review of CM51-07.  We first consider the requirements for the spatial distribution of the trigger level agreed by the Commission in the preambular paragraphs of the conservation measure. We use these requirements as the basis for a risk assessment method to distribute the catch.  In the second section, we review the best scientific evidence available for krill, krill predators and the fishery to underpin the risk assessment. In the third section, we develop the mathematical basis for the risk assessment and the means of distributing the trigger level in Area 48.  We then provide some worked examples using the method based on data from the second section.  Lastly, we suggest an approach for undertaking the review and providing advice on a future spatial distribution of the trigger level.  The results provide the basis for establishing a spatial distribution of the trigger level across subareas and amongst SSMUs for 2016/17 and beyond.  They indicate that some SSMUs may have a disproportionately higher risk of the effects of fishing if the catch within a subarea is concentrated in those SSMUs.  Nevertheless, the results also indicate that the distribution of catch amongst subareas in the existing conservation measure are approximately the right magnitude, although there may be justification for setting the percentage of the trigger level for Subarea 48.4 to zero.