Developing reliable, repeatable, and accessible methods to provide high-resolution estimates of fishing-effort distributions from vessel monitoring system (VMS) data

Lee, J., South, A. B., and Jennings, S. 2010. Developing reliable, repeatable, and accessible methods to provide high-resolution estimates of fishing-effort distributions from vessel monitoring system (VMS) data. - ICES Journal of Marine Science, 67: 1260-1271. Vessel monitoring systems (VMS) are used primarily for fisheries enforcement purposes, but also provide information on the spatial and temporal distribution of fishing activity for use in fisheries and environmental assessment and management. A reliable, repeatable, and accessible method using readily available software for estimating fishing effort from unprocessed VMS data is developed, tested, and applied. Caveats associated with the method are identified, and the biases introduced by our assumptions are quantified. Application of the method provides a high-resolution description of gear-specific fishing activity by UK vessels. An index is developed to describe variation in the spatial pattern of fishing effort generated by different gears. The proposed method for VMS analysis involves removing duplicate VMS records and records close to ports, calculating the time interval between successive records to identify periods of activity, linking each record to a vessel and gear type, differentiating fishing and non-fishing activity, and summing fishing records in time and space to estimate fishing effort. The approach is a step towards the development of standardized methods to facilitate wider exchange and use of European VMS data. A clear audit trail for the methods of VMS analysis already used to inform management needs to be documented.