Updated SCAA Base Case assessment for Greenland halibut

The Statistical Catch-at-Age (SCAA) assessment methodology applied to the Greenland halibut resource in 2017 is updated to take further data now available for the years 2017 to 2019 into account. Results are reported for a Base Case corresponding to that considered in 2017, and some sensitivities related to uncertainties about some recent catch-at-age data. Apart from a slight downward shift in the overall biomass scale, results are essentially unchanged from those in 2017, and the sensitivity runs show little difference from the Base Case. There has been a recent slight downward trend in exploitable biomass, but this is likely to reverse quite soon given that the estimates of incoming recruitment are of above average strength. New data and recent resource trends are consistent with predictions made in 2017 when a revised management procedure for Greenland halibut was adopted.