Download FAR 2018/43 – Evaluating the effects of changes in the frequency of research abundance trawl surveys and age frequency sampling on the hoki, hake, and ling stock assessments

The frequency of the Chatham Rise and Sub-Antarctic trawl surveys has been reduced from annual to biennial. The effect of the reduction on biomass estimates and their uncertainty is investigated using: (a) generic simulations, (b) retrospective analyses, and (c) forward projection simulations. The retrospective analyses and forward projections simulations were conducted for the hoki, hake, and ling stock assessments. The difference between annual and biennial scenarios was found to be small.