2018 Updated horse mackerel assessments

The assessments for the two hypotheses (reduced catchability and a one-off additional mortality event) for the recent reduced Desert Diamond catch rate are updated to take one further year’s data into account. The 2017 CPUE somewhat increased above its 2016 value, and now almost returned to the values typical before the 2014 low. If the same basis as in the recent past is used to make management recommendations with an unchanged effort limitation, the total allowable midwater catch would be set at 23 851 MT. However the assessment results, given this data update, are suggestive of the catchability hypothesis now being more plausible than the additional mortality hypothesis. This in turn suggests that consideration should be given to some increase in the cap on effort, which would lead to a concomitant increase in the midwater TAC