A recent study, using Life Cycle Assessment (LCA), suggests that natural fluctuations in stock abundance in fisheries may cause high variability in environmental impacts related to the Atlantic mackerel fishery in the Basque Country. The aim of this study is to analyze environmental fluctuations through time of a demersal species, European hake (Merluccius merluccius), caught by Basque bottom trawlers in European waters. The three-step LCA+DEA method, which combines LCA with data envelopment analysis (DEA), a linear programming tool, was implemented to assess annual variability of the environmental impacts in the period 2001-2006. The identification of the varying operational efficiency levels between vessels and the potential environmental gains of input minimization were explored. Results showed variations of up to 25% in the environmental impacts between years, although minimal environmental gains were identified through operational benchmarking, given the similar efficiency values between vessels. Hence, it was observed that despite substantial interannual changes in the impacts, there is limited potential for environmental impact reduction for the assessed environmental dimensions. Environmental and operational differences between years impeded setting a particular best-performing target for this production system, attributable to the high variance observed in input/output distribution through time. Finally, results seem to confirm the lower fluctuations in environmental impacts for demersal species fishing in comparison with those of small pelagic fish. © Published by Central Fisheries Research Institute (CFRI) Trabzon, Turkey.