Seasonal variations in the feeding ecology of Nephrops norvegicus in the Adriatic Sea: insights from stomach contents and stable isotope analyses

Abstract

Norway lobster Nephrops norvegicus is one of the most important commercial species in the Mediterranean. This study focused on its feeding ecology in an important fishing ground within the Adriatic Sea, using an integrated approach of stomach content (SCA) and stable isotope (SIA) analyses. The simultaneous use of these tools represents a modern and complete approach that provides reliable data over time and reflects the feeding strategy of the analysed species. Monthly sampling was carried out (January-December 2019, July and October 2020; 589 specimens) to investigate seasonal changes in diet and trophic level. Variations in fullness, gonadosomatic and hepatosomatic indices were analysed to explore changes in feeding and variations in energy requirements linked to reproductive needs. Results showed that N. norvegicus mostly prey on decapod crustaceans and fish. Seasonal variations in prey consumption were likely linked to the reproductive patterns of the species. SIA results confirmed SCA findings and placed N. norvegicus at a high position within the benthic food web. Overall, considering that the Adriatic Sea represents one of the most important and productive fishing areas for Norway lobster, this study provides critical information for an effective ecosystem approach to fisheries management of this resource.