The global fishing industry faces increasing pressure to meet international decarbonization targets and stringent environmental regulations (IMO 2021; UNCTAD 2023). A significant portion of the Mediterranean coastal fleet still operates with legacy propulsion systems that lack modern digital monitoring capabilities. Bottom trawling, in particular, remains one of the most energy-intensive fishing methods due to the high hydrodynamic drag and seabed disturbance caused by traditional heavy steel doors operating in permanent contact with the benthos (Cheilari et al. 2013). This pilot study, conducted in the North-Western Mediterranean (Port of Llançà), evaluates the energy and environmental benefits of replacing conventional bottom doors with semi-pelagic (flying) trawl doors on a vessel of 19.55 m LOA and 294 kW. The research aims to quantify reductions in fuel consumption, engine load, and greenhouse gas emissions while assessing the hydrodynamic performance of the new gear. The methodology relies on a non-invasive, differential ultrasonic flow metering system installed on the engine's fuel lines to ensure high-precision data. Additionally, an inertial measurement unit with GPS was utilized to correlate fuel data with vessel motion and specific fishing phases. The semi-pelagic doors were equipped with real-time acoustic sensors to monitor parameters such as spread, symmetry, and seabed clearance. The findings indicate a fuel consumption decrease in the order of 20–25%, which is consistent with previous industrial studies in the Mediterranean (Grimaldo et al. 2015). This reduction directly correlates with lower CO2 emissions and a significantly diminished impact on the benthic ecosystem. Beyond this specific case, the project provides a scalable framework to support the energy transition of the Mediterranean fleet, aligning with the European Green Deal and EMFAF objectives (European Union 2021; Generalitat de Catalunya 2022).
Oyamburu et al. (Mon,) studied this question.