Marine areas - Cod 2025
Published 13 Oct 2026
The status of both the eastern and western Baltic cod stocks is poor. In both stocks, the spawning stock biomass is below reference points, and the degradation of the environmental status is considered a key factor weakening the status of the stocks. In the eastern cod stock, anoxia in the deeps of the southern Baltic Sea, a lack of suitable food for juveniles, and an increased parasite burden have prevented the recovery of the stock. In the habitats of the western cod stock, periodic bottom-water hypoxia has been observed, which is likely also linked to climate change. The recovery of the cod stock is considered unlikely. Since the beginning of 2015, a discard ban and a minimum conservation reference size of 35 cm have been in force for commercial fisheries (cod under 35 cm may not be sold for human consumption).
Eastern cod stock (ICES Subdivisions 24–32)
The spawning biomass of the eastern cod stock was highly abundant during the "cod years" of the 1970s and 1980s. This was due to a period of higher-than-average salinity, which ensured sufficient oxygen levels in the high-salinity water required for cod reproduction, while suitable prey for cod was also abundant. As conditions deteriorated, the stock and catches declined rapidly, and since the 1990s, the spawning biomass is estimated to have been mostly below reference points. There have been short, better periods, most recently following the major saltwater inflow (salt pulse) at the turn of 2014–2015. At that time, the spawning biomass initially increased but then rapidly declined again and has remained low since the last years of the 2010s.
Due to data limitations, it has no longer been possible to conduct analytical stock assessments and forecasts; instead, the assessment is based on observable trends. Cod has been caught mainly as bycatch in flatfish fisheries. Cod growth has been slow in the stock's core distribution areas in the southern Baltic Sea, and the condition of individuals has been poor for several years. Individual condition (the ratio of weight to length) deteriorated until 2010, after which it has fluctuated without a clear trend. Natural mortality has increased and is estimated to be significantly higher than fishing mortality, which is now almost non-existent. Individuals of the eastern cod stock reach sexual maturity at a substantially smaller size in the stock's core area than before; similarly, the spawning stock consists of smaller cod than in the past.
With the spread of the grey seal to the southern Baltic Sea, its parasite, the nematode Contracaecum osculatum, also became abundant. Fish serve as its intermediate hosts, and the worm's larvae are sometimes highly abundant, especially in cod livers. In the slow-growing and small cod of the southern Baltic Sea, heavy parasite loads may cause mortality even before the fish reach catchable size.
Although the situation for cod in the southern areas of the Baltic Sea has been poor for a long time, the situation along the coast of the Baltic countries and in the Åland Sea does not appear quite as bad. Since the mid-2010s, more cod have been caught in the Åland Sea than in the preceding 20 years. Cod caught in Åland have continued to be in good condition, and some of them are very large. In recent years, however, their size structure has shifted year by year toward larger individuals.
According to ICES advice, applying the precautionary approach, there should be zero catches from the eastern cod stock in 2027.
Oxygen Depletion and Declining Salinity Weaken Baltic Cod Stocks
The poor status of Baltic cod stocks is caused by reduced salinity and, in particular, the extensive oxygen-depleted bottom areas in the Baltic Proper. Recent German studies indicate that oxygen depletion and the underlying effects of climate warming also affect the habitat of the western Baltic cod stock.
The status of both the eastern and western Baltic cod stocks would likely be much the same today even if cod fishing had ceased after the 1980s. In the mid-2010s, major saline inflows rapidly improved cod reproduction and growth. However, the effect was short-lived because oxygen depletion in deep-bottom areas quickly returned.
Parasites and Food Shortages Also Contribute
Suitable water layers with sufficient oxygen and salinity for the development of eastern Baltic cod eggs are scarce. In addition, oxygen-depleted or nearly oxygen-depleted bottom areas lack suitable crustacean prey (including opossum shrimps, amphipods and isopods) needed by juvenile cod to grow large enough to switch to a fish-based diet.
The livers of slow-growing cod in the southern Baltic Sea are infected by parasitic nematode worms that use cod as an intermediate host and grey seals as their final host. These parasites often cause premature death in cod weighing less than half a kilogram. The relatively few juvenile cod that drift with currents into the more favourable conditions of the Åland Sea grow rapidly to a large size and tolerate the same parasite much better.
Environmental Changes Have a Significant Impact on Baltic Fish Stocks
The impact of overfishing on changes in Baltic fish communities has probably been overstated because the full effects of a degraded habitat have not been fully understood.
In the advice provided by the International Council for the Exploration of the Sea (ICES), fisheries management aims to ensure that depleted fish stocks can recover, or at least that the conditions needed for recovery are maintained. Therefore, when the habitat of a fish species deteriorates, fisheries management must also be adapted to the reduced productivity of the stock. Such adaptations have been particularly necessary in advice concerning cod and salmon fisheries.
The status of Baltic cod, herring and perhaps also salmon stocks would very likely improve (while the sprat stock might decline) if the overall environmental condition of the Baltic Sea improved. The most serious problems are excessive nutrient loading and extensive oxygen-depleted bottom areas. The relatively limited inflow of fresh oceanic water into the Baltic Sea, and the resulting decline in salinity, have contributed to the spread of oxygen-depleted bottoms and have also made fish communities along the Finnish coast less marine in character.
Western cod stock (ICES Subdivisions 22–24)
The western cod stock has been relatively weak since the late 2000s. In the mid-2010s, the spawning biomass fell below reference points, and the stock has continued to deteriorate since then. Results from research surveys suggest high mortality, even though catches have decreased to very low levels. The condition factor of cod has worsened. This is potentially driven by summertime hypoxia in near-bottom waters caused by eutrophication, water warming due to climate change, and the impacts of these changes on factors such as cod food resources.
According to ICES advice, applying the precautionary approach, there should be zero catches from the western cod stock in both 2026 and 2027.
