Impacts of shrimp fisheries on habitats and communities in the coastal seas of the Federal States of Schleswig-Holstein, Hamburg and Lower Saxony
Bottom contacting fishing is being criticised for destroying seafloor habitats. However, there is a broad range of combinations of fishing gears, habitats and associated ecosystems questioning whether such general statement holds true. Each possible combination of gear and habitat type will exhibit a different degree of impact or damage to seafloor integrity. Although the mechanisms how fishing impacts on seafloor integrity are well understood, results cannot easily be applied to specific regions and fishery – habitat combinations. Each and every benthic habitat and associated ecosystem is unique, so that for a reliable evaluation of fishing impacts, the specific combination of habitat and fishery needs to be assessed. CRANIMPACT will specifically address the brown shrimp fishery in the Southern North Sea for a re-evaluation of their impacts on seafloor integrity of the Wadden Sea National Park. A combination of experimental fisheries and historic data will form the basis for the analyses.
Since the foundation of the Wadden Sea National Parks of Schleswig-Holstein and Lower Saxony in 1986, the impact of fisheries on the Wadden Sea ecosystem has been a matter of debate. This was partly reflected in the wording of respective legislation stating that on the one hand commercial fisheries was permitted but on the other, that fisheries had to adhere to the principles of the national parks. An ecosystem research project for the Wadden Sea 1989-to1996 was intended to provide scientific data for an efficient management of the Wadden Sea, however, the Ministerial Declaration of Tønder 2014 refuelled the discussion on ecosystem impacts of fisheries by introducing a 'Framework for Sustainable Fisheries'. One of the aims of the Ministerial Declaration was to facilitate stakeholder participation and dialogue in all 3 countries Denmark, Germany and The Netherlands in order to provide the same conditions for sustainable fisheries everywhere. New research techniques e.g. underwater-GPS-positioning and advanced hydroacoustics as well as satellite based assessments of fisheries coverage allow for a reappraisal of shrimp fisheries impacts after some 25 years.
Pilot studies carried out by means of underwater video transects reveal the presence of a rich fauna despite relatively high turbidity (video sequence below, Lister Ley, April 2019).
Science, policy makers and the public
The project follows two complementary approaches: Analyzing recent and historical composition of benthic communities along gradients of fishing intensity, and recovery of benthic communities and habitat structures after experimental fishing. For the first time, long-term unfished reference areas from the Danish Wadden Sea are included in the analysis. Next to biological impacts physical and morphological changes to seafloor integrity are studied. Commercial shrimp cutters as well as smaller research vessels specialised in shallow water research will be used for sea sampling and carrying out the experimental work. Research areas will span from “Lister Tief” north of Sylt island close to the Danish border to “Blaue Balje” in the southern part of the German Wadden Sea off Lower Saxony.
Next to practical work at sea time series data on benthic communities as well as satellite data from the vessel monitoring system for fisheries (VMS) will be analysed to include the long-term adaptation of the benthic communities to fisheries into the evaluation of fishing impacts. Benthos analyses will specifically address ecosystem functioning and ecosystem services. Investigations of historic changes in the Wadden Sea have shown that biological traits analyses is especially well suited to study and understand fundamental changes in biological systems.
Results of the project will provide the scientific basis for implementation of measures and long term management plans for the coastal brown-shrimp fishery, as e.g. demanded for ecolabeling the fishery by Marine Stewardship Council (MSC). Moreover, our results will help to objectify the discussion between nature conservation and fisheries about achieving conservation goals of the Wadden Sea National Park substantially.
How does the brown-shrimp fishery with beam trawls in the southern North Sea impact different habitats (Lanice- areas, areas with sand bars) ?
What characterizes a long-term unfished area as compared to lightly and more frequently fished areas?
How can natural disturbance and fisheries impacts be combined in a joint assessment ?
8.2018 - 7.2022
Project status: ongoing