Bottom-up Control Regulates Fisheries Production at the Scale of Eco-Regions in the European Seas

We use primary productivity data, derived from remote sensing images, associated with catch data for the period 1998-2004 to characterize the productivity of eco-regions in the northeast Atlantic, Mediterranean, Black and Baltic Seas then to analyze the strength of the trophic linkage between primary productivity and marine fish production in the European seas. Mean annual primary production (PP) derived from an ocean-color based model was highly contrasted between eco-regions, exceeding 500 gC m-2 y-1 in the Marmara and North Seas but being less than 150 gC m-2 y-1 in the faroes, Adriatic-Ionian and Aegean-Levantine Seas. Fisheries production expressed in mean annual yield and primary production required to support catches (PPR) greatly varies between eco-regions, respectively from 0.02 t km-2 and 0.7 gC m-2 y-1 for the oceanic northeast Atlantic eco-region to 6 t km-2 and 130 gC m-2 y-1 in the Marmara Sea. Linear regression models showed significant positive relationships between PP and yield as well as between PP and PPR, suggesting a strong linkage between marine productivity and fisheries production in the European seas. This bottom-up control appeared moreover consistent in time, as recent mean annual yield for the period 1998-2004 reflected well long-term yield averaged over the last three decades. We argue that such a large-scale coupling is due to energy transfers along the food web from phytoplankton to predators through predation processes, primary productivity driving the production of living marine resources and their exploitation at the scale of eco-regions. Our findings have an important bearing for an ecosystem approach to fisheries, particularly to estimate the capacity of eco-regions with regards to sustainable exploitation. This is further relevant in a context of climate change, as variations in PP linked to global warming could strongly modify fisheries production in the future.

CHASSOT Emmanuel;  MELIN Frederic;  LE PAPE Olivier;  GASCUEL Didier; 

2007-08-09

INTER-RESEARCH

JRC35516

https://publications.jrc.ec.europa.eu/repository/handle/JRC35516,   

10.3354/meps06919,