Fish and sharks

R&D to answer ecological and economic questions

The development of ORE is generating concerns about their potential impacts on the marine environment, particularly on sharks and fish. Indeed, ichthyofauna is a major component of the ecosystem and fishing is an important activity in coastal maritime regions. ORE farm projects therefore raise ecological and economic questions. Will the animals permanently flee the area after the turbines are installed? Does habitat modification have a negative impact on the fishery resource and more generally on the ecosystem? To what extent do offshore renewable energies have an impact on sharks and fish? All of these legitimate questions require a scientific approach for an objective answer. This is why France Energies Marines, its members and partners are conducting joint research on this topic.

New habitats that are naturally attractive to fish

Offshore wind turbines can be considered as Fish Aggregating Devices (FAD) and large numbers of some species are expected, especially under the floating structures. The presence of new solid structures at sea also represents new habitats. Cables, piles and floating structures will thus be rapidly colonised by algae and fixed living invertebrate organisms, which are at the base of marine food webs. The offshore wind farms will therefore attract other species, mainly high trophic level fish, to feed on the structures. This creation of new habitats, combined with the FAD effect, will lead to an increase in biomass and species richness throughout the water column in offshore wind farms, as well as the appearance of new food webs. It is therefore to be expected that fish communities will become more resilient when subjected to other anthropogenic or environmental pressures. France Energies Marines is conducting several studies, in collaboration with its partners, to understand how and to what extent wind farms can modify marine communities (TROPHIK, APPEAL and WINDSERV projects). This work concerns the modelling of future food webs, taking into account parameters such as the location area or the type of farm.

The reserve effect of ORE farms and its possible benefits for the fishing

For safety reasons, wind farms should be partially or totally banned for fishing activities. The increase in fish biomass induced by this ban is referred to as a reserve effect. After a few years of operation of the farm, a threshold should be reached and some of the individuals will leave the protected area. This phenomenon is called spill-over. By modelling these two types of effects, France Energies Marines and its partners aim to identify the possible benefits of the implementation of a ORE farm for fishing activities (TROPHIK, APPEAL and WINDSERV projects). Several scenarios are tested in order to measure the precise consequences of banning different practices (e.g. bottom trawling, pelagic trawling, dredging, nets…) over different periods of the year. The size of the farms, the number of wind turbines, the potential limitation of fishing and the effects of climate change are integrated into the models developed. This makes it possible to anticipate changes in the structure of fish communities and the repercussions they could have on human activities. This work also aims to assess the extent to which wind farms can enable France to achieve the objectives set out in the Convention sur la diversité biologique.

Characterisation of the ecological functioning of particular habitats

ORE projects are developing in offshore environments that are sometimes little known because access conditions limit the number of scientific studies aimed at better understanding the structure and functioning of these ecosystems. For example, several offshore wind farm projects in France and other countries involve the deployment of turbines in areas where underwater dunes are forming. Underwater dunes are complex sedimentary assemblages, present worldwide, which shelter fauna adapted to extreme conditions and with unique functions. They provide habitat for small forage fish (e.g. sand eels) which are prey for higher trophic levels (seabirds, carnivorous fish) and therefore play an important role in the functioning of marine ecosystems. Within the framework of France Energies Marines’ activities, scientists are seeking to better understand the communities of organisms living in these particular environments: meiofauna, benthic macro-invertebrates, zooplankton, ichthyofauna (DUNES project). These different groups are monitored during oceanographic campaigns. Fish populations and zooplankton are characterised (specific diversity, abundance) and several individual parameters are measured (total length, diet, age). This knowledge will be used to model the potential effects of the installation of ORE farms in these particular ecosystems. 

Photo credit: Thomas Pavy

Interlocutors

Lydie Couturier

Research Fellow in Marine Ecosystems and ORE Interactions

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