Connectivity analysis of European hake spawning grounds under climate change scenarios

The identification of connectivity hotspots in the marine environment provides important insights into the spatial distribution, dispersal, settlement, and development of the first life stages of many pelagic and demersal species in the ocean. In a scenario of climate change, mutating environmental conditions can alter these connections, resulting in modifications in the dispersal patterns of marine species. Understanding the potential consequences of these modifications is key to sustainable fisheries management. In this work, we carried out a connectivity analysis for the European hake (Merluccius merluccius) in the waters of the Adriatic and Ionian seas to explore the seascape connectivity of the species within the basin. Starting from Hake’s juveniles density distribution generated with MEDITS data in the context of the Seawise Project (Horizon 2020), we ran backwards Lagrangian simulations to reconstruct spawning grounds and forward simulations to build a connectivity matrix. Then, we evaluated a set of network metrics to assess the role of different portions of the study area in the dispersal of early life stages. We ran three distinct simulations in as many time periods, representing respectively the current situation (2010-2019), near future (2040-2049) and far future (2090-2099), the latter two under two climate change scenarios (RCP4.5, RCP8.5). The results of our analysis show dense connectivity hotspots in the Adriatic Sea, with interesting differences on both latitudinal and longitudinal scale. We show that this methodology can provide insights into the spatial dynamics of demersal marine species and how changing environmental variables may affect their distribution in the future.