Fish Strategy Wadden Sea
The drivers are unclear, but increased water temperature, damage of coastal habitats (through sand nourishment, dredging and fisheries) and heightened predation by top predators probably play a role.
This is the main conclusion of reseach that is commissioned by the Programme Towards a Rich Wadden Sea.
The reports Wadden Sea Fish Haven (research and policytools) and the Fish Fact Sheets can be downloaded from the PRW website.