Abstract

On the North Sea bottom lie numerous pipelines to link oil- or gas offshore drilling units, - platforms and processing stations on land. Although pipeline tubes are coated and covered with protective layers, the pipelines risk being damaged through man-made hazards like anchor dropping and fishing activities with bottom trawls.Fugro Survey B.V. works towards integrated risk assessment of pipelines for amongst others TAQA Energy B.V. Spatial maps of fishing activity would contribute to this risk assessment. Therefore, WMR was tasked to quantify the amount of fishing activity in the vicinity of TAQA Energy B.V. pipelines. Fishing activity has been quantified at a spatial scale of approximate 3800 m2 blocks (68m by 56m) using fishing Vessel Monitoring System (VMS) data in 2017 (1/10/2016-30/9/2017).The results in this study show that small beam-trawling vessels are active within, and just outside the 12 mile zone around the pipelines. In total, between 0 and 8.7 minutes per year of trawling is accumulated over the whole period within each spatial block. For the larger beam-trawlers, only present outside the 12 mile zone, in total between 0 and 1.8 minutes per block and year of trawling is accumulated. A conversion of these numbers to fishing intensity, a measure for number of times a block is fully trawled, shows that sections of the pipeline are trawled between 0 and 3.4 times a year. This fishing intensity is below the range of 5-10 times a year estimated in the most intensively fished areas of the North Sea.The indicators calculated in this study, reflecting number of potential interactions (fishing effort) of trawling vessels with the pipelines and the potential severity of these interactions (fishing intensity), may contribute to the risk assessment. It should be noted, however, that owing to seasonal changes in fish distribution and yearly changes in fishing gear characteristics, these maps do not provide an accurate base for the prediction of future fishing impact.