Estimating uncertainty in deriving spatial distribution of blue ling landings from vessel monitoring system (VMS) data and implications for delineating marine protection boundaries to the northwest of the British Isles

Recent years have seen a rapid increase in the development of restricted fishing areas to protect vulnerable marine ecosystems and species-specific fish stocks. The current study focuses on one such area to the northwest of the British Isles where, in 2009, the European Commission (EC) introduced protection areas for spawning aggregations of southern blue ling (Molva dypterygia) in European Union (EU) waters. High-resolution data derived from logbook entries and satellite-based vessel monitoring systems (VMS) are used to estimate spatial and temporal patterns of blue ling fishing activity. However, certain assumptions must be made regarding whether vessels are engaging in fishing activity at any individual monitoring point, leading to uncertainty in estimating activity in the vicinity of protection area boundaries. The study aims to apportion blue ling landings reported by ICES rectangles of 1° latitude × 0.5° longitude inside and outside the protection areas and the data are assessed at different spatial and temporal scales. From the methods evaluated, initial results of the impact of EU conservation measures on fishing activity during the spawning period are inconclusive.