The production of biomass in the Wadden Sea is one of the highest in the world compared to other similar coastal areas, most significantly demonstrated by the numbers of fish, shellfish and birds supported by the area. Its ecosystems sustain wildlife populations well beyond its borders.

The Wadden Sea is one of the most important areas for migratory birds in the world. Around 6 million migratory birds can be found in the Wadden Sea at one time, and an average of 10-12 million pass through it in autumn and spring every year.

The amount of biomass found on mussel beds is 2,000 g per m², compared to about 65 g per m² on tidal flats.