The HELCOM report “State of the Baltic Sea” (1) provides an update on the environmental situation in the Baltic Sea for the period 2011–2016:

Eutrophication: 97 % of the Baltic Sea area is affected by eutrophication and 12 % is assessed as being in the worst status category. Inputs of nutrients from land have decreased, but the effect of these measures are not yet generally reflected in the status of the marine environment. The eutrophication status has deteriorated in four out of the seventeen open sea assessment units since the last five year period (2007–2011), and improved in one. Only a few coastal areas are currently unaffected by eutrophication, but an improving trend is seen in some indicators and sub-basins.

Hazardous substances: Levels of contaminants are elevated and continue to give cause for concern. However, the number of improving trends outweighs the number of deteriorating trends in the monitored hazardous substances. The integrated contamination status is mainly influenced by polybrominated fame retardants and mercury, together with cesium, deposited after the accident at the Chernobyl nuclear power plant in 1986. Levels of radionuclides are now at acceptable levels in some sub-basins and can be expected to be so in all of the Baltic Sea by 2020. Acute pollution events from oils spills have decreased.

Marine litter: HELCOM is developing core indicators for assessing marine litter, but they are not yet operational and thus no assessment of status has been possible at this time. Beach litter monitoring is ongoing in several countries, showing that the number of beach litter items ranges from around 50 on reference beaches to up to 300 on urban beaches, per 100 metres of shoreline. Plastic litter is a special concern due to its risk to the environment and its slow rate of degradation. Around 70 % of the litter items in the Baltic Sea are derived from plastic materials.

Underwater sound: Underwater sound is a widely distributed pressure in the Baltic Sea, caused by various human activities. Areas with high levels of continuous sound mainly coincide with areas of high vessel traffic. Up to 1 700 impulsive sound events were registered in 2011-2016. The majority of these stem from explosions, whilst around 11 % are linked to pile driving in connection to construction work. It is not known how many marine species are impacted by underwater sound, and thus no assessment of status has been possible at this time.

Non-indigenous species: Around 140 non-indigenous species have so far been recorded in the Baltic Sea. Of these, 12 are new for the Baltic Sea during 2011–2016. In addition, an unknown number of previously arrived non-indigenous species have expanded their distribution range to new sub-basins in the Baltic Sea. The regional objective is that there should be no primary introductions of non-indigenous species due to human activities during an assessment period and thus, good status is not achieved.

Species removal by fishing and hunting: Three out of nine assessed commercial fish stocks are in good status with respect to both biomass and fishing mortality rates. Eight stocks are currently lacking an evaluation with respect to both of these aspects. Hunting of marine mammals and birds is minor. Seals are generally protected, but hunting is permitted in some countries, restricted to populations above a limit reference level and with a positive growth rate. Water birds are hunted in some countries, whereas in others they have strict protection.

Seabed loss and disturbance: Less than one percent of the Baltic Sea seabed was estimated as potentially lost due to human activities, while roughly 40 % of the Baltic Sea seabed was estimated as potentially disturbed during the assessment period. The estimates are based on the spatial extent of human activities but have not been linked to pressure intensity. Hence, no assessment of adverse effects on the seabed has been made at this time.

Habitats: For benthic habitats, there is indication of good status in six of thirteen assessed open sea areas, based on estimates limited to soft bottom habitats. Coastal areas show good status in about one third of the assessed Baltic Sea region. Pelagic habitats are assessed based on core indicators representing primary productivity, and in some sub-basins also zooplankton. Based on the available indicators, open-sea pelagic habitats achieve good status only in the Kattegat. Coastal pelagic habitats show good integrated status in about one fifth of the assessed areas. The assessments of habitats are still under development and additional elements will be included in the future.

Fish:  The assessment of fish from a biodiversity perspective indicates good status in about half of the assessed coastal areas. In the open sea, good status is achieved only in the Bothnian Bay. Two out of five assessed pelagic fish stocks (herring in the central Baltic Sea and the Gulf of Bothnia) have good status, and one of four assessed demersal stocks (plaice). Core indicators for the migratory species salmon and sea trout show mixed results with strong geographical differences. Eel is critically endangered.