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Rapport2016Öppen tillgång

Essential fish habitats (EFH) : conclusions from a workshop on the importance, mapping, monitoring, threats and conservation of coastal EFH in the Baltic Sea

Kraufvelin, Patrik; Hekim, Zeynep; Bergström, Ulf; Florin, Ann-Britt; Lehikoinen, Annukka; Mattila, Johanna; Olsson, Jens

Sammanfattning

Many fish species in the Baltic Sea are highly dependent on shallow and sheltered coastal habitats that they use for spawning, nursery, feeding and migration. Still, the role of these essential fish habitats (EFH) for the development and support of fish stocks and communities has received relatively little attention, even though there is general consensus among scientists about their critical importance. Little is also known about the major threats to EFH, and their conservation status in different countries has previously not been reviewed. As EFH often are found in the same parts of the coastal zone that are also highly valued by humans, this gap in knowledge needs to be addressed. Hence, there is an urgent need to focus more thoroughly on the importance, mapping, monitoring and protection of EFH and also the driving factors and mechanisms behind the changes we observe in their status. Only this way, we will be able to predict and mitigate future effects of environmental change in these valuable habitats and to create adaptive management plans. The main objectives of this project were to 1) organize a workshop for experts around the Baltic Sea on the importance, protection of and threats to coastal EFH (including an overview of the methods used for the mapping and monitoring of these habitats), and 2) based on the outcome of the workshop, produce a review paper in an international scientific journal about the state of the art of the subject for the Baltic Sea, including knowledge gaps and future research needs. Here, we report the results of the project, focusing on the outcome of the workshop. From the workshop (organised during 2nd-4th June 2015 in öregrund, Sweden) we conclude that there are only few quantitative studies available concerning the importance of EFH for fish stocks. This evidence is in turn quite complex and do not necessarily provide straightforward answers. Nevertheless, for some coastal species, indirect evidence exists and sufficient data are also available to carry out further quantitative analyses. More evidence on the role of EFH for fish production could potentially also be achieved using spatial and temporal data analyses, stage-structured modelling and otolith chemistry techniques. Based on qualitative results/analyses, it can be reasoned that EFH are very important and valuable for the provisioning of rich fish communities and for fish production. This conclusion is reached, despitethe still quite low degree of targeted studies that are focusing explicitly on the role of the habitats and that are providing straight quantitative relationships. Most likely the importance of these habitats has been underestimated in the past and more studies could contribute to pinpoint their ecological importance. For the monitoring and mapping aspects of EFH in Baltic Sea countries, a lot of data seems to be available. Different sampling methods are used for a wide range of both coastal and offshore species and life stages (from eggs, larvae, YOY (young of the year) to adult fish). The use of these data in producing habitat maps has for long been poor, but the situation is now improving rapidly in many countries as a result of national and regional underwater mapping and inventory programs. In this sense, not only habitat mapping and mapping of fish distribution (fish in different life stages) are of importance. Also the mapping of major threats, pressures and environmental background conditions should be performed. This would ensure maximum availability and optimized use of information necessary for efficient management and for the improvement of marine spatial planning. The threats to and conservation status of EFH suggest urgent and diverse management solutions. Eutrophication, climate change, coastal construction and development, invasive species and fishery seem to constitute the major threats to the habitats. Among these threats, the physical pressures, including for example marine shipping/boat traffic and its associated infrastructure (like dredging), physical exploitation of shore areas and trawl fishery, tend to be more easily manageable. These activities disturb fish habitats both directly and indirectly, and are typically more serious to fish reproduction and juvenile stages. The conservation status of EFH is generally poor, mainly due to that fisheries management and nature conservation in the Baltic Sea region historically have been separated. Internationally, however, many marine ecological studies have shown how mutual benefits may be reached through an integrated management of fisheries and habitats. This gives EFH a central role in management, merging the interests of fisheries management and habitat protection, and simultaneously attracting a lot of scientific interest to associated research questions. The results of the current project hence suggest that there are data for quantitative analyses to support the role of EFH for fish production, a potential to initiate, develop and synchronize future monitoring and mapping of the habitats, and that there is an increasing awareness for the protection and increased concern for the sustainability of these shallow coastal systems. The outcome of this project could serve as a basis for improving cooperation between Baltic Sea countries in this field, which in the long run could result in both harmonized monitoring and mapping methods of the EFH in the Baltic Sea and a strengthened management. The work also provides important input for developing indicators to assess the status of EFH and for the implementation of international agreements and legislative acts as the Baltic Sea Action Plan (BSAP), the Habitats Directive (HD) and the Marine Strategy Framework Directive (MSFD).

Publicerad i

TemaNord
2016, nummer: 539ISBN: 978-92-893-4664-1, eISBN: 978-92-893-4665-8Utgivare: Nordic Council of Ministers