A critical approach to the use of published data for baseline characterisation of marine fish assemblages: An exercise on Portuguese coastal waters

► Published data on fish abundance covering a wide range of conditions was collected. ► Fish assemblages were grouped and characterised using multivariate methods. ► Both species composition and functional guild data were used in the analyses. ► Data comparability and scale were severe limitations of such an approach. ► The exercise provided a hands-on demonstration of issues and achievements.