Fishing effects in northeast Atlantic shelf seas: patterns in fishing effort, diversity and community structure. III. International trawling effort in the North Sea: an analysis of spatial and temporal trends

This paper describes trends in beam and otter trawling effort in the North Sea from 1977 to 1995, Data are presented as total hours fishing by English , German, Norwegian, Scottish and Welsh vessels for the period 1977-1995, a nd by Danish, Dutch, English, German, Norwegian, Scottish and Welsh vessels for the period 1990-1995. Analyses of temporal trends indicated that total international trawling effort in the entire North Sea has increased slowly since 1977 and that it is currently (1995) 2.25 million h yr(-1) of which 55% is due to beam trawling, Spatial analyses indicate that the proportion of beam trawling effort increases from north to south. Plots of annual fish ing effort by ICES statistical rectangle (211 boxes of 0.5 degrees latitude x 1 degrees longitude) indicate that the majority of fishing effort in the North Sea are concentrated in a very few rectangles. Thus mean annual tota l fishing effort (1990-1995) was less than 2 000 h in 29% of rectangles and less than 10 000 h in 66% of rectangles. Total effort exceeded 40 000 h in 4% of rectangles, The results indicate that assessments of the average are a swept by trawls in the North Sea give a poor indication of the direct imp acts of trawling on the biota. Some areas are intensively fished but many o thers are not. Our dataset is likely to underestimate trawling effort in th e southern North Sea (ICES Area IVc) because data for Belgian and French ve ssels were not available. However, the absence of French and Belgian data w ould not significantly alter total trawling effort estimates from the centr al (IVb) and northern (IVa) North Sea. Crown copyright (C) 1999 Published b y Elsevier Science B.V. All rights reserved.