Fish stocks in EU waters are assessed by the International Council for the Exploration of the Sea (ICES). Scientists from the UK's fisheries laboratories contribute to the undertaking of these assessments. The ability to perform scientific assessments is directly linked to the quality of fisheries data. In some fisheries, for example, the quality of catch and effort data are deemed to be insufficient or the available catch data appear to conflict with data from research surveys. In such cases, as a consequence, quantitative scientific assessments are not available.
In the absence of a quantitative scientific assessment, it is not possible to define a stock's status with respect to safe biological limits.