Country Data | Department for Environment. Food and Rural Affairs (DEFRA). 2019. Time series values produced according to methodology described in Metadata document for the national indicator can be consulted at https://sdgdata.gov.uk/14-4-1/ | Indicator based on 57 stocks for which data are available. of which 17.5% of fish stocks have unknown value. An increase in ‚Äòunknown' status for spawning stock biomass may be due to the updating cycle by which stock assessments are made.