Fuel performance and carbon footprint of the global purse seine tuna fleet

Modern commercial fisheries are heavily dependent on the input of fossil fuels throughout their supply chains, particularly diesel inputs to fishing vessels. Fuel use intensity of fisheries varies with regard to target species, gears employed, region of fishing, technologies used, skipper behaviour, and other factors. Those fisheries that consume relatively less fuel not only have a lower carbon footprint, up to the point of landing, but are also in a favourable position to meet future fuel and emissions regulations, and may be more resilient to the effects of volatile fuel prices and limited oil resources. We measured fuel inputs to purse seining vessels targeting primarily skipjack (Katsuwonus pelamis) and yellowfin (Thunnus albacores) tuna. Data reported represent 28% of worldwide landings of skipjack and yellowfin by purse seiners in 2009. These vessels burned, on average, 368 L of fuel per tonne of wet weight landings. This corresponds to a fuel-related carbon footprint of 1.1 kg CO2 per landed kg of tuna, lower than that of average marine capture fisheries as well as most forms of land-based animal protein production. Interestingly, the use of FADs in purse seine fisheries for tuna was found to be inversely correlated with efficiency, going against conventional logic that FAD use improves efficiency. This study is the largest snapshot of tuna fuel inputs to date, providing a baseline against which future performance can be measured, and an indicator for consumers concerned about the carbon footprint of their food choices.