ارزیابی تأثیر یک بسته بندی ماهیگیری با تجزیه و تحلیل فضایی تلاش و فرود: مطالعات موردی در دریای بالتیک غربی

Commercial fisheries in the Western Baltic Sea (WBS; ICES Subdivisions 22–24) are dominated by Danish and German vessels. By combining and processing logbook and Vessel Monitoring System (VMS) data for Germany and Denmark, we compare patterns of spatial effort allocation and the origin of the landings before (2005–2007) and during (2008–2010) implementation of the EU long-term management plan (LTMP) for cod. This management plan is likely to have affected the temporal and spatial extent of fisheries in the WBS. Changes that took place between 2005 and 2010 on the large scale of the WBS were therefore considered when selecting an appropriate stable reference period to inform and evaluate small-scale effort-displacement scenarios in the Fehmarn Belt. The WBS fisheries appear not to have been restricted by effort limits until 2010, but rather by total allowable catches (TACs) for cod. The amount of cod landed in the WBS decreased, and the origin of these landings shifted farther east without affecting the seasonal effort allocation. Landings of cod have also decreased in the Fehmarn Belt area, and since 2008, sprat has been the species most landed there. The planned construction of the Fehmarn Belt Fixed Link connecting Denmark and Germany could lead to the temporal closure of fishing activities. Three different effort-displacement scenarios were tested to determine how lost landings, caused by a fishing closure of a corridor near the link during construction, could be counteracted by moving the activities to a nearfield area. To compensate for lost landings, the best strategy appears to be redistributing fishing effort of sprat-targeting métiers to areas that have had relatively high catch rates (landings per unit of effort (LPUE)) or with large absolute sprat landings, assuming spatial stability of sprat distribution in the area. Because high effort did not lead to large sprat landings in all locations, effort displacement to high effort areas may not compensate for lost sprat landings, particularly for mixed fishery métiers that also landed herring.