Mariculture development in the Baltic Sea is feeble in comparison to for example the North Sea. In case of mussels this is mostly due to the Baltic’s low salinity, which causes their low growth rate and their smaller sizes. So far (status of February 2019) there are three types of maricultures that have been established in the Baltic:
- mussel farms (in Denmark, Germany, Sweden, Finland (Åland), Estonia and Latvia),
- algae cultivation (Estonia, Latvia, Denmark and Sweden) and
- fish maricultures (in Denmark, Finland and Sweden).
While fish farming is carried out on a commercial basis in the Baltic (Denmark and Finland), the majority of mussel farms and algae cultivation sites are or were established as pilot research in projects such as AQUABEST, SUBMARINER, SEAFARM and Baltic Blue Growth. Only a few of them are based on commercial basis (in Denmark and Sweden).
Findings from BBG indicate that mussels may grow quite intensively in the western and proper Baltic: Kiel farm (Figure 1) had a yield of 3,30 kg/m rope after 1 year of growth [harvest of 5 tons on 0.21 hectares water surface] and at Sankt Anna BBG focus farm after 2 years of growth the yield was 3,40 kg/m rope [harvest of 78.7 tons on 4 hectares water surface] (Minnhagen S. et al, 2019).
Mussels may be used as food for humans, feed for animals, source of biogas, a component in pharmaceutics or ingredient for cosmetics (e.g. collagen). In addition to the commercial uses, blue mussels – as other bivalves – are also a provider of several ecosystem services, out of which the most important regulating services are nutrient removal (Olivier et al, 2018). Thus, mussels contribute to a reduced nutrient load in the Baltic Sea. Other ecosystem services provided by mussel farms (Gundersen et al. 2016) are: supporting services (increasing biodiversity by providing substrate for algae and refuge for small animals, creation of unique habitats, changing the system from a turbid, plankton-dominated habitat to a highly diverse and productive benthic system, filtering considerable quantities of particulate matter), provisioning services (food and feed production), regulating services (Increase the ecological resilience, binding CO2 when building their shells, improving water clarity, decreasing the concentration of chlorophyll), cultural service (increasing the culinary offer, use as bait for fishing, indirectly supporting tourism industry through creation of attractive wildlife such as marine mammals and birds or increasing possibility for swimming / beaching).
Based on the experience of the Baltic Blue Growth (BBG) project’s focus farms and via intensive communication with mussel farmers and the MSP practitioners, issues important from the MSP perspective for further development of mariculture in the Baltic Sea region are addressed in this proposal: optimal environmental conditions for mussels’ growth, role and utilization of national and regional aquaculture development plans, legal regulations and formal procedures, role and power of associations representing the sector, potential conflicts with other marine use and ways to minimize / mitigate them.
Assuming that the ecosystem payment scheme to the Baltic blue mussel farms – as proposed by the Baltic Blue Growth project – will be established and operational, mussel farming should be considered as an important business activity, that have to be addressed in the maritime spatial planning process. In some cases, mussel farming will come into conflicts with other sea uses. Thus, it is important to have a clear, and as far as possible uniformed planning methodology among countries in the maritime spatial planning process.