MEDITERRANEAN AQUACULTURE AND SUSTAINABILITY: HOLISTIC ASSESSMENT OF EUROPEAN SEA BASS (DICENTRARCHUS LABRAX) AND GILTHEAD SEA BREAM (SPARUS AURATA) FARMING

Aquaculture is one of the fastest-growing sectors globally and is increasingly recognized as a primary solution to meet the rising global demand for seafood. This trend is also present in the Mediterranean region, where two of the most important species in terms of both production and economic value are European Sea Bass (Dicentrarchus labrax) and Gilthead Sea Bream (Sparus aurata). These two species are typically farmed both in coastal sea cages and land-based systems. Both methods, while effective for large-scale production, present distinct challenges related to environmental concerns, including energy consumption, resource use, nutrient discharge, biofouling, and feed-related emissions.
The central goal of this thesis is to provide a comprehensive assessment of the environmental performance of different aquaculture systems using Life Cycle Assessment (LCA) methodology. Through this approach, the thesis aims to identify key hotspots in aquaculture production, analyse potential strategies for mitigating environmental impacts, and explore innovative farming technologies such as Integrated Multi-Trophic Aquaponic systems (IMTAcs). The overarching objective is to evaluate the environmental footprint of aquaculture systems and suggest pathways for improvement, particularly by optimizing energy use, feed efficiency, and infrastructure design. A multi-criteria decision analysis (MCDA) model was also applied to a case study with the aim of providing a comprehensive sustainability assessment.
This thesis is divided into three main sections each incorporating scientific studies that focus on different aspects of the environmental impact of Sea Bass and Sea Bream farming in the Mediterranean region.
Chapter 3 offers an in-depth analysis of the current environmental performance of Sea Bass and Sea Bream farming, including a review of published LCA studies, comparisons between farming systems, and energy analysis. The first step of this work was to review existing LCA studies on the farming of Sea Bass and Sea Bream in the Mediterranean, summarizing and comparing the main results, identifying environmental impact hotspots, and pointing out methodological concerns. The review revealed that feed production is the most significant contributor to environmental impacts, particularly regarding greenhouse gas emissions and resource use. Additionally, most studies have employed a mass-based functional unit and "cradle-to-gate" boundary. This study also highlighted gaps in geographic representation and transparency in data reporting and underscored the need for overall sustainability assessments. Following the review, a comparison of different farming systems, including traditional sea cages and land-based systems, was performed. The results indicated that sea cage systems have lower environmental performance compared to land-based facilities, as the latter require substantial energy inputs for water pumping, filtration, and aeration. Also the energy analysis confirmed that coastal sea cages benefit from lower direct energy consumption but still face challenges related to the production of feed, which remains the dominant factor in overall environmental impacts. This chapter provides a baseline understanding of the environmental challenges associated with Mediterranean aquaculture and serves as a foundation for exploring potential mitigation strategies in the following sections.
Chapter 4 focuses on two potential strategies to mitigate the environmental impact of Sea Bass and Sea Bream aquaculture. The first strategy explored is an innovative Integrated Multi-Trophic Aquaponic system (IMTAcs), which integrates fish farming with the cultivation of detritivorous filter-feeding organisms (such as mussels, clams, and polychaetes) and halophytic pla