Effect of FAD closure on the energy efficiency of the purse seine fishery: FAD vs free swimming school strategy

Abstract

Tropical tuna purse seine fishing is one of the most important fisheries in the world, employing two strategies to fish: fish aggregating devices (FAD) and free-swimming school (FSC). International tuna management commissions have regulated the use of FADs to make the fishery more sustainable, by means of temporal FAD usage prohibitions, but the viability of these management measures is under debate. This study aims to (i) evaluate the energy efficiency, based on the fuel use intensity (FUI), carbon footprint and profitability (<euro>catch/<euro>fuel) of the tropical purse seine fishery, and (ii) determine the differences between fishing strategies, FAD versus FSC, in the Atlantic Ocean during FAD closure and non-closure periods by assessing, for the first time, the effect of FAD closure regulations in the energy efficiency and carbon footprint of the fishery. Data from 73 fishing trips (2019-2022) from 7 vessels were analysed, including vessel specifications, trip details, fuel usage, and catch data. FAD trips were more energy efficient, with lower carbon footprints and higher profitability (456 L/t; 1241.4 kgCO2/t; 2.93 <euro>catch/<euro>fuel) compared to FSC trips (1810 L/t; 4932.3 kgCO2/t; 2.54 <euro>catch/<euro>fuel) and mixed trips (588 L/t; 1602.0 kgCO2/t; 2.52 <euro>catch/<euro>fuel). During FAD closure, FSC trips had higher FUI and lower profitability (2736 L/t; 1.75 <euro>catch/<euro>fuel) than non-closure periods (541 L/t; 2.76 <euro>catch/<euro>fuel). FAD closure impacts the energy efficiency, carbon footprint, and economic profitability of the tropical tuna purse seine fishery; without FAD sets, FSC results in high FUI and low profitability.