Abstract Limiting the use of fossil fuels in fisheries is important for industry competitiveness and for achievement of greenhouse gas reduction targets, particularly in countries like Iceland where fishing contributes significantly to both the economy and emissions. This article analyses harvesting fuel intensity in Iceland between 2002 and 2017 and examines potential underlying drivers. Fuel intensity for demersal vessel segments and species declined over the period whereas pelagic intensities increased slightly. Variation was strongly correlated with stock levels, highlighting the potential for stock rebuilding to reduce fuel intensity. Correlation was weaker in the demersal sector. A potential explanation is that increased abundance of cod led to choke effects as vessels sought to avoid cod. Analysis of operational data indicated a lower average engine load for a sample of pelagic vessels compared to demersal vessels, suggesting engine load-balancing as an opportunity to improve engine efficiency. Finally, a potential policy instrument for reducing emission in ITQ-managed fisheries is presented, in which harvesters own and trade individual emissions quota based on total allowable emissions for the fishery.