Assessing the Accuracy of High Spatial Resolution Effort Data: Comparing VMS and Logbook Data in the California Groundfish Trawl Fishery

Fisheries management is increasingly being conducted at finer scales of spatial resolution.  The spatial distribution of fish stocks is recognized as being an important aspect of stock abundance and spatial management tools, such as marine reserves, have become common.  Information on the spatial distribution of fishing effort is critical to conducting this type of spatially-oriented management for at least two reasons.  First, harvest information from individual vessels can generate data used in higher spatial resolution stock assessment.  Second, understanding the location choice behavior of fishermen is important in understanding the effects of policy on both fish stocks and the fishermen themselves. We compare for consistency two sources of two high-resolution data sets on fishing location: self-reported logbook data and vessel monitoring system data.