## 1 Introduction
### Emissions from the Fishing Sector  
The fishing sector represents a great part of the food source and the economy of countries with access to the sea. According to the Food and Agriculture Organisation (FAO), more than half of the world's fish production is generated by developing countries. China is the world leader in the number of captured fish, while Norway is the leader in Europe [72]. Fishing vessels come in different sizes, equipped with different types of gear depending on the target species. They operate on unfixed routes and change course frequently, which makes their power needs highly variable. Around 86% of all motorised fishing vessels have a length of less than 12 m, while less than 2% refer to industrial fishing vessels of over 24 m in length and more than 100 GT [73].  
Fishing activities affect aquatic ecosystems in terms of visible pollution such as plastic litter and oil spills, invisible pollution such as microplastics and pollutant dumping (different chemicals), underwater noise, bycatch, ghost fishing, over-exploitation of fish, etc. [74]. Fossil fuel consumption is the most significant environmental problem related to fishing activities, affecting the environment and human health [75,76]. Most fishing vessels are powered by conventional fossil marine fuels, like MDO and Marine Gas Oil (MGO), whose combustion results in GHGs, NOx, SOX, and PM, contributing to global warming and acidification [77]. The fishing sector itself accounts for 1.2% of global oil consumption, which results in the release of 134 million tonnes of CO2 emissions into the atmosphere [78].  
To support sustainable fishing and reduce harmful emissions, replacing traditional power systems with alternative ones fuelled with cleaner fuels needs to be performed. [PERSON] et al. [68] analysed the environmental and economic impact of several alternative  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Year**} & \multirow{2}{*}{**Studies**} & \multicolumn{2}{c}{**Coverage**} & \multirow{2}{*}{**Scope**} \\ \cline{3-3} \cline{5-5}  & & & **Fuels** & **Test Case** & \\ \hline \multirow{4}{*}{\
\begin{tabular}{c} \(\text{Ca}^{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{ \text{\text{\text{\text{ \text{ \text{ }}}}}}}}}}}}}}\) \\ \end{tabular} } \\ \cline{2-5}  & [PERSON] and [PERSON] [64] & LSFO; LNG; ammonia & container ship & Economic analysis \\ \cline{2-5}  & [PERSON] et al. [20] & Diesel; gasoline; LPG; bio-LPG & small fishing vessel & LCA \\ \cline{2-5}  & [PERSON] et al. [22] & HFO; LNG; LPG; methanol & bulk carrier & LCA \\ \hline \multirow{4}{*}{
\begin{tabular}{c} \(\text{C}^{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{ \text{\text{\text{\text{\text{ \text{ \texttext{ \texttexttext{ \texttexttexttext { }}}}}}}}}}}}}}\text  
fuels implemented on a trawler that performs fishing activities in the Adriatic Sea. The LCA comparison of different powering options indicated that the use of ammonia on board results in the highest life-cycle GHG emissions. The most environmentally friendly solution is a fully electrified vessel. From an economic point of view, the LCCA results showed that hydrogen is the most expensive option for the trawler, while the most cost-efficient option is the use of methanol as an alternative fuel. [PERSON] et al. [20] analysed LPG and bio-LPG compared to conventional marine fuels for fishing vessels. The performed LCA indicated that LPG results in 30% lower GHG emissions than diesel-powered fishing vessels, while bio-LPG can reduce GHGs by over 65%. The nexus between all-electric fishing vessels and Isolated Energy Systems (IES) with a high share of renewables was investigated by [PERSON] et al. [79]. The study confirmed that all-electric ships, charged in island grids, can reduce the critical excess of electricity production, operating costs of IES, and the emissions of CO\({}_{2}\).