​​​​​The Baltic Sea is a semi-enclosed shallow sea with an average depth of 60 m, where one third of the area is less than 30 m deep (Figure 1). This ecoregion has many islands and a long and diverse coastline, especially in the northern areas. It is characterized by strong temperature and salinity gradients, from relatively warmer and saline waters in the southwestern part to cold and almost freshwater in the northernmost parts. In addition, there is strong permanent vertical stratification for much of the Baltic Sea. The northernmost parts are covered by ice in winter. Based on its bathymetry and hydrology, the Baltic Sea can be sub-divided into three main areas:

• the transition area, consisting of the Belt Sea and the Arkona Basin
• the central Baltic Sea, consisting of the deep areas of the Bornholm Basin, Gdansk Deep, Gotland Basin and the Gulf of Riga
• the northern Baltic Sea, including the Gulf of Bothnia and the Gulf of Finland and the Archipelago Sea

Management and governance institutions

Nine countries border the Baltic Sea, and a further five countries are partly within the catchment area (Figure 2). The catchment area has a total population of around 85 million. All countries bordering the Baltic Sea, except Russia, are EU Member States, and all countries and the EU are contracting parties of the Convention on the Protection of the Marine Environment in the Baltic Sea (the Helsinki Convention). The convention establishes the Baltic Marine Environment Protection Commission, commonly referred to as the Helsinki Commission or HELCOM. HELCOM has adopted the Baltic Sea Action Plan (BSAP) to restore good ecological status of the marine environment by 2021. The focal issues of the BSAP are eutrophication, biodiversity conservation, hazardous substances, and maritime activities. The goals of the BSAP to a large degree overlap with those of the EU’s Marine Strategy Framework Directive (MSFD) and the Water Framework Directive (WFD). This overlap has resulted in strong coordination in the implementation of measures.

Policies regarding commercial fisheries in the Baltic Sea are regulated under EU’s Common Fisheries Policy (CFP) and bilaterally with Russia. Recreational fisheries are mostly managed at the national level.

Fisheries advice is provided by ICES, the European Commission’s Scientific, Technical and Economic Committee for Fisheries (STECF), the Baltic Sea Advisory Council (BSAC), and BALTFISH. BALTFISH is a regional body involving the eight EU Member States bordering the Baltic Sea, which submits joint recommendations to the European Commission. BSAC is an advisory body composed of representatives from the commercial fisheries and other interest groups, mainly environmental NGOs.

In the Baltic Sea, the protected areas network is a combination of HELCOM Baltic Sea Protected Areas (BSPAs) that were established to protect valuable marine and coastal habitats and the Natura 2000 network of the EU Birds Directive and EU Habitats Directive (Figure 1) that are protecting certain natural habitats and species. Many of BSPAs and Natura 2000 sites overlap. The network of MPAs in the Baltic Sea is gradually expanding and is now close to 15% of the total sea area.