TABLE 1.

Classification of the 198 metrics from the 25 national fish‐based river assessment methods subjected to the European intercalibration process. Metrics are classified according to their types and the unit in which they are expressed. Metrics belonging to types and expressed in units allowing calculation from eDNA data are in bold letters

Metric Types	Metric Units
	Species richness	Relative abundance	Relative biomass	Density	Biomass	Expert judgment
Species trait‐based metrics
Habitat guilds	19	12	1	2
Migratory guilds	5	4		1
Perturbation tolerance	13	15		1
Reproductive guilds	14	13
Trophic groups	8	10		5
Other metrics
Whole assemblage	2	7		2	4
Taxonomy‐based metrics	9	6		8	2
Biogeographical status	5	5		1
Health alteration		2
Length or age class	1	10		8		3