We evaluated the spatial distribution of otter trawl fishing effort and catches resulting from the imposition in 1994 of year-round and seasonal groundfish closed areas off the NE USA, Vessel locations were available from logbooks, vessel monitoring system (VMS) data thin) many of the largest vessels, and from observer records. There was high spatial coherence between VMS- and observer-derived trawling locations. Prior to establishment, 31% of trawl effort (1991-1993) occurred within the 22 000 km(2) of area that would eventually be closed year-round. In 2001-2003 about 10% of effort targeting groundfish was deployed within I km of the marine protected area (MPA) boundaries. and about 25%. within 5 km, Density gradients, consistent with spill-over from MPAs, were apparent for sonic species. Average revenue per hour trawled was about twice as high within 4 km of the boundary. than for more distant catches, but the catch variability was greater nearer closed area boundaries. Seasonal closed areas attracted more fishing effort after opening than prior to closure even while average epue was the same or lower. Spatial resolution of traditional data sources (e.g., logbooks) was too crude to discern detailed MPA-related effects, as revealed by high-resolution vessel positions from VMS and catch data obtained by observers. (c) 2005 International Council for the Exploration of the Sea. Published by Elsevier Ltd. All rights reserved.