Could population and community indicators contribute to identify the driver factors and describe the dynamic in the Flemish Cap demersal assemblages?

Abstract

Flemish Cap is an isolated fishing ground located in the international waters of the Northwest Atlantic Fisheries Organization area (NAFO). In the last decades, the Flemish Cap demersal community has been subjected to strong and variable fishing intensities affecting different stocks over time. In this work, three ecological indices for individual populations (abundance, biomass, and intrinsic population rate of growth) and five community indicators (total abundance and biomass, community synchrony, ABC curves and proportion of non-commercial/commercial species) have been applied to data of 29 fish and 1 shrimp species to analyse the dynamics of the whole ecosystem and the major demersal fish assemblages. Different periods were detected, which may be explained by differences in the exploitation patterns and pressure for different stocks, prey-predators relationships and other environmental drivers affecting the reproductive capacity. This study shows that the selected community indicators are appropriate to detect changes in the demersal community of Flemish Cap in response to fishing, predation and variability in recruitment success. It has been also demonstrated that treating each depth zone separately help us to better understand trends and that analyses revealed different trends for different parts of the community during periods with different fishing pressure. This knowledge could be useful to support management policies