Towards an Ecosystem Approach to Fisheries for Nephrops Norvegicus and Meluccius Merluccius Inhabiting the Central Adriatic Sea

Abstract

This study presents the development of a Model of Intermediate Complexity for Ecosystem assessments (MICE) for testing management scenarios for the stock of European hake (Merluccius merluccius) and Norway lobster (Nephrops norvegicus) inhabiting the Central Adriatic Sea. These two species represent the target species, as well as the predators, of this study. They are mainly fished by Italian and Croatian bottom trawl fishery, accounting for both the highest landings and commercial value among demersal species in the area. The specific circulation of the Adriatic Sea is responsible for strong nutrient recycling processes within this area, resulting in a rich fishing ground extensively exploited by Italian and Croatian fishing vessels, make it an interesting case study for the development of an Ecosystem Approach to Fisheries (EAF). Here, an EAF was developed using the MICE approach, since it is well adapted to test specific management questions, as required by this study. The MICE was developed in a step-wise manner. Firstly, single-species stock assessments for both the target species were pursued, allowing the evaluation of the state of these resources and permitting the production of the input values to be included within the MICE. Secondly, the diet of the target species were examined and prey items portioned in four groups; consumption of each prey group by each predator was modelled using a Holling Type II functional response. Finally, predator and prey dynamics were linked within the MICE model, using a modified biomass dynamic model to project them into the future and testing different management strategies. The best management scenario resulted to be the protection of adults, which produced the most beneficial results for both predators and prey groups.