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    Using the Risk Assessment Framework to spread the catch limit in Subarea 48.1

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    Document Number:
    WG-FSA-2021/16
    Author(s):
    V. Warwick-Evans and P.N. Trathan
    Submitted By:
    Dr Vicky Warwick-Evans (United Kingdom)
    Approved By:
    Dr Chris Darby (United Kingdom)
    Abstract

    We provide an update on the implementation of the risk assessment in Subarea 48.1 resulting from discussions held during WG-EMM 2021. We have used track changes when adding textual changes incorporated since WG-EMM and all figures have been updated. In this version, we use an updated layer for winter krill density, evaluate some new scenarios and also include some sensitivity analyses.

    We have applied the risk assessment framework, developed by Constable et al. (2016), to Subarea 48.1, with the aim of identifying the most appropriate management units by which to spatially distribute the local catch limit for the commercial fishery for Antarctic krill. We use the best available data for implementing the approach which was endorsed by the Commission in 2019. The framework is flexible and can accommodate new data to improve estimates of risk in the future.

     

    We evaluated 36 catch distribution scenarios for assessing risks from krill fishing in Subarea 48.1. For each scenario we calculated the regional baseline risk, and the regional desirability risk. Baseline risk is defined as the risk to predators and krill and is based on predation pressure and the proportion of juvenile krill in each management unit. Desirability risk is defined as the risk to predators and krill as for the baseline risk, but also accounting for the desirability of a management area to the fishery i.e. more catch may be attributed to areas where the fishery has previously fished (desirable areas) than in the baseline scenario. We show that the spatial distribution with which the fishery currently operates presents some of the highest risks of all scenarios evaluated. Managing the fishery at much smaller scales has the lowest risk but may necessitate a high level of management interaction with the fishery.

    This implementation can provide advice to CCAMLR for short-term management and could provide a template for the rest of Area 48. We highlight that each data layer impacts the outcome of the risk assessment and recommend that updated estimates of the distribution, abundance and consumption of krill, and estimates of available krill biomass will be key as CCAMLR moves forward to develop a longer-term management strategy.

    A benefit of the risk assessment framework is that CCAMLR now has a tool for direct comparison of risks associated with alternative catch distributions at an appropriate spatial scale for management. We suggest one approach for choosing between scenarios, based on regional risk (either baseline or desirability).

    We provide advice about the scale at which the krill fishery can be managed, but highlight important issues that should be discussed, including uncertainty, before CCAMLR agrees the design of spatial management units. We highlight that for the Risk Assessment to give a robust estimate of risk then it is important that the management units are at a similar scale as fishery operations. If management units are large, and the fishery operates in just a small portion of a particular unit, then the measure of risk estimated by the Risk Assessment will not reflect the risk posed by the fishery in that management unit.

    Finally, we highlight that our endeavours have been the result of a community effort and we are grateful to those that have provided data and advice.

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