Changes in abundance of demersal fish species in the North Sea between 1906–1909 and 1990–1995

A comparison of catch rates of demersal fish during beam trawl and otter trawl surveys carried out in the period 1990-1995 and 1906-1909 indicates lower abundance in recent years for the total assemblage as well as for individual groups. There appear to have been shifts in the community associated with reduced diversity and evenness indices. Length-frequency distributions of roundfish and flatfish show a shift towards smaller-sized fish.