Table 1 Definition of components of the primary systematic review question as per the CEE guidelines [31]

Marine benthic biota

Short or long-term use of bottom fishing gear

Changes in abundance measures (density/biomass, etc.), and diversity measures (e.g. species richness) of benthic biota. Changes in abiotic components and other biological variables will also be recorded where available

Areas with no bottom fishing (e.g. marine protected areas), or low levels of bottom fishing (e.g. sites with effort restrictions)

Any primary study that provides raw data measures of numerical abundance, biomass or diversity of benthic biota. The methods of the primary study should be either a 'before and after’ or 'control and impact’ study (or both i.e. BACI), or based on comparisons of at least two different levels of bottom fishing exposure or comparisons between areas exposed to bottom fishing and control areas.