A global history of bottom trawling and disturbance to continental shelf systems

The bottom trawling industry, which provides roughly one quarter of global seafood landings, has a great environmental cost. By dragging nets and other collection devices over the seabed, trawling degrades and impacts seabed habitats, catches a range of non-target species, and has potentially significant implications for our climate via disturbance of sedimentary carbon stocks. Despite this, we have a relatively poor understanding of how, when, and where, intense historical trawling impacts occurred on continental shelf seas. In this presentation, we describe our work to reconstruct the long, lost history of bottom trawling, from its growth in the North Sea during the 18^th century, to its global spread and industrialisation in the 1950s. We make use of sources such as national archives, government records, historical accounts, and popular media, to estimate the size and fishing power of early trawling fleets during the 19^th and early 20^th century. We combine this with descriptions of expanding trawling grounds and past trawling gears to map seabed impacts backwards in time. Latterly, we describe the expansion of bottom trawling post-1950 using trawling landings and effort data collated by the Sea Around Us Project (University British Columbia). We do this by allocating fleet data to fishing ports around the world, and subsequently modelling fishing effort and behaviour across the continental shelves for the period ca. 1950 to 2010. In doing so, we aim to provide a first synthesised global history of bottom trawling, as well as estimates of shelf seabed areas impacted by these activities. The results of this study are expected to shed new night light on the scale and extent of seabed disturbance caused by the bottom trawling industry, while emphasising the importance of historical context for addressing and managing contemporary marine conservation and today’s climate challenges.