In his keynote lecture at Oceans Past V, Adriaan Rijnsdorp, IMARES, the Netherlands, shared his work on the historical development of the bottom trawling impact on demersal fish populations and the benthic ecosystem with Oceans Past participants.
Benthic ecosystems provide important goods and services, such as fisheries products, and support regulation and cultural services. There is serious concern about the adverse impact of fisheries, in particular bottom trawling, on benthic ecosystems. The impact of bottom trawling is determined by the footprint of the fishery (spatial extent), the type of fishing gear used, and the sensitivity of the sea bed habitat and benthic ecosystem. Recent work has for the first time generated maps of the distribution and intensity of bottom trawling in the northeast Atlantic showing on one hand the intensive exploitation of particular parts of the sea bed, while other parts are not trawled or are trawled at an intensity of less than once a decade. This raises the question how we got to this situation.
In an upcoming paper, along with my co-authors, I will present a reconstruction of the historical development of intensity and spatial extent of bottom trawling. The reconstruction is based on a variety of data sources (archaeological, historical, fisheries technological, geological, fisheries) with particular focus on the North Sea. Commercial exploitation of marine fish resources dates back to at least the fourteenth century. The main species were targeted with passive gears such as drift nets (herring) and hook and lines (cod, ling, haddock). Although concern about bottom trawling is expressed in historical documents going back to the late fourteenth century, the available fishing technology restricted the use of bottom trawls to the flat sandy bottoms in shallow coastal waters.
Steam trawlers in Great Yarmouth, UK, 1930s. Photo: Cefas.