Evaluation de l'impact des dragues à coquilles Saint-Jacques sur les communautés benthiques en baie de Seine

The impact of King scallop dredges on benthic communities in the Bay of Seine has been studied through the analysis of benthic species associated to King scallops collected during the stock assessment surveys between 1998 and 2011 on the one hand, and on the other hand on the trends of fishing effort during the same period. The aims of this study is in a first step to draw a partial picture of the state of benthic communities in the Bay of Seine and in a second step to assess if changes in these communities could have been caused by changes in the activity of dredging. The analysis of the benthos species allows us to highlight the evolution of the abundance and spatial distribution of 17 species of benthic macrofauna. The abundance of most of these species has increased (Norway cockle, Queen scallop, spidercrab, green sea urchin, blunt tellin, dog-cockle, banded carpet shell) or remained relatively stable (starfish, swimming crabs, velvet crab, hermit crabs, purple heart urchins, whelk and circular crab). Fishing effort has decreased but could not be precisely quantified. Our results do not yet indicate whether the trends to increase or stability of the abundance of the main benthic macrofauna could be related to the decrease in fishing effort. Further studies of natural variables that could influence the abundance of these populations, such as irregular recruitment and predation or competition relationships within the benthic communities seems to be necessary in order to test this hypothesis. It should be noted that the original benthic communities have probably suffered the greatest impact in the early stages of the King scallop fishery, so this study was therefore conducted on communities already impacted. The absence of data from the initial state or control areas prevents direct comparison between original and current communities.