Report on assessing trawling impact in regional seas

Baltic Sea Benthic ecosystem impacts from demersal fishery in the western Baltic is assumed to come mainly from Nephrops trawling in the central and southern Kattegat, mussel dredging in the Belt Sea, and mixed cod trawling in the western Baltic Sea.These fisheries both impact the seabed, as well as produce substantial amounts of discards. The western Baltic Sea offer a unique opportunity to analyse the benthic effects of fishingthanks to the closure of Oresund to towed gears since the 1920s, and the introduction of the Kattegat MPA in2009 (including cod closure) and the western Baltic Sea Natura-2000 areas. Furthermore an extensive benthic nationalmonitoring and data collection effort has taken place in the area over a number of years, which can be usedto investigate spatial and temporal differences in the development of benthic communities in (chronically) towed and non-towed areas. To evaluate benthic impacts of towed gears in the Baltic Sea a number of gear technological innovations to reduce effort, benthic contact of fishing gears, and discarding are evaluated. There are conducted experimental fisheries in relation to evaluation and comparison of direct ecosystem and habitat impacts, catch efficiency (target/by-catch/discard/invertebrates), selectivity (discard), energy efficiency, and economic efficiency (vessel specific cost-efficiency/cost-benefit analyses) of different gear modifications compared to standard gears. Furthermore, the case study evaluates potential fishing closures directed towards sensitive benthic habitats and communities. A review of known regional benthic impacts of fishery with demersal towed gears in the area is evaluated with focus on the mussel dredging, demersal cod trawl fishery and Nephrops trawl fishery, where latter is also compared to Nephrops creel fishery. Subtidal dredging and benthic trawling in the area has been reported to affect the benthic fauna and flora as well as to change the structure of the sea bed...