The growing impact of seals and cormorants on Estonian fisheries
This article was featured in Eurofish Magazine 4 2025.
The Estonian fishing -industry faces mounting pressure from two -powerful natural -competitors: the great cormorant (Phalacrocorax carbo sinensis) and the grey seal (Halichoerus grypus). Both species are native to the Baltic region but have seen -unprecedented -population growth in recent -decades. This surge has led to significant consequences for coastal fisheries and aquaculture, prompting national and regional management responses.
Cormorants and grey seals are both apex predators that feed primarily on fish. Their increasing numbers have placed them in direct conflict with human fishers. According to data from the Estonian Ministry of Regional Affairs and Agriculture, coastal fisheries extract approximately 12,000 tonnes of fish annually. This figure is matched by the estimated fish consumption of cormorants and closely followed by grey seals, which consume around 11,000 tonnes per year. Combined, these predators now remove more biomass from the sea than human fishers, a reversal that has altered the marine resource balance in Estonia’s coastal waters.
Herki Tuus, Fisheries Policy Department, Ministry of Regional Affairs and Agriculture
Cormorant numbers surge
While historically present, cormorants were a rare sight in Estonia until the 1980s, says Herki Tuus from the Fisheries Policy Department in the Ministry of Regional Affairs and Agriculture. The population began expanding rapidly in the 1990s, particularly the continental subspecies P. carbo sinensis. Improved environmental conditions, such as lower levels of heavy metals in the aquatic ecosystem, as well as the Birds Directive, which protects all naturally occurring wild bird species in the EU, -contributed to this growth. The speed at which it has multiplied justifies the term invasive as the species takes over habitats and damages areas with its acidic excretions compounding the malign ecological impact. By 2024, the number of breeding pairs had reached 44,000, a number that is estimated to increase by 10% a year, with a total summer population of around 160,000 individuals including fledglings. Cormorants consume approximately 0.4 kg of fish per bird per day. Given their population size, their total fish consumption now matches or exceeds that of Estonia’s entire small-scale coastal fishery. This level of extraction has raised concerns not only about fish stock sustainability but also about the economic viability of coastal fishing activity. The birds are also seen as a threat to inland aquatic ecosystems. When colonies form on the mainland, they are difficult to manage as they nest in trees and their feeding habits can decimate fish populations in rivers and lakes. In coastal areas, on the other hand, they nest on the ground on rocky islets in the sea or along the shore and are easier to control.
Cormorants can nest in trees as well as on the ground. Oiling the eggs,
a method of control, is easier when the nests are on the ground.
A three-pronged management strategy
To address the problem, Estonia has implemented a comprehensive cormorant management strategy. A renewed cormorant management plan was introduced in 2024 and further updated for 2025. This plan includes three main tools: egg oiling, deterrence, and hunting. Egg oiling involves spraying food-grade oil onto eggs to prevent hatching. The method is considered a humane way to suppress population growth over time, as adult birds are not killed. In 2023, Estonia authorised oiling in 10 colonies, affecting around 3,000 nests. In 2024, this expanded to 12 colonies and 14,000 nests. For 2025, the plan includes oiling in 35 colonies, potentially impacting 28,000 nests, or more than 74% of the nests in those locations. Deterrence is used mainly in spawning areas such as the Pärnu River, where large flocks of cormorants have threatened smelt populations. Non-lethal deterrents like loud noises and lights are deployed to scare birds away from these critical habitats and to prevent them from settling as a colony. Hunting is permitted from August through December, with approximately 1,000 to 1,500 birds taken annually. While the numbers are modest compared to the population, hunting is seen as part of a broader strategy to limit damage. The government has even begun promoting cormorant meat as a culinary option to increase public interest in hunting the bird. The target of the management plan is to reach back to 9,500 breeding pairs of cormorants.
However, while Estonia may implement its own management strategy, Mr Tuus is keenly awaiting an EU-wide strategy the roadmap of which is currently being drafted and should be -released in mid-2025. How the plan is finally adopted will also have a -bearing on national efforts to manage cormorants, some of which have been stymied by the courts, where environmental and ornithological groups have challenged cormorant-managing measures. Mr Tuus hopes that an EU-wide plan will carry legal strength that will assist national authorities. Although Estonia lost an early case due to insufficient justification, subsequent licensing decisions have been better documented, and the most recent court ruling has so far favoured the state. Moreover, the efficiency of management measures increases in relation to the number of countries that apply them. The Estonian plan will work better if similar measures are also being applied by our neighbours, Mr Tuus points out.
Seals pose a threat to fish stocks, fishers, and their gear
Grey seals have followed a similar trajectory. After being severely affected by pollution in the 1970s and 1980s, their numbers have rebounded in recent decades thanks to environmental recovery and protection measures. The current population in Estonian waters is estimated at over 7,000 individuals. Each of these consume up to 5-10 kg of fish per day. Their impact extends -beyond fish -consumption to gear damage, -particularly in gill net fisheries. Seals often raid nets, tearing them, eating some fish, but also partially consuming, damaging, or killing the other fish in the net, rendering the catch unfit for human consumption. A 2009 study valued the damage at €1 million, representing 20–30% of the revenue from coastal fisheries. Given the increased seal population, the present-day figure is likely much higher. Some compensation for damaged gear is available but the amount is negligible and the paperwork formidable so very few fishers apply. The use of seal proof gears and deterrent devices however is supported through the EMFAF (European Maritime, Fisheries, and Aquaculture Fund), but they work best with trap nets. For gillnets they are less efficient. The nature of seal damage also creates operational uncertainty. Fishers report interrupting their activity for days when seals are sighted, as the risk of ruined gear and lost catch is too high. Seals are not merely competitors; they are a direct economic threat to small-scale fishers. In fact, according to Mr Tuus, seals are considered an even bigger threat than cormorants because of the damage they do to fishing gear.
Seals too are a menace for coastal fishers as they compete for
the same stocks, prey on catches, and damage fishing gear.
In terms of the total volume of fish consumed, seals and cormorants are responsible for two thirds, while fishers are responsible for a third. This creates a tension because fish stocks must attain good status. One way is to restrict the fishery but limiting this enough to -compensate for what -cormorants and seals take would mean virtually terminating the fishery altogether. From a fisheries management point of view, Mr Tuus says, we therefore need to manage the pressure on stocks from all three sources.
Seal management and legal constraints
Seal hunting is allowed in Estonia under a protection and management plan adopted in 2015. Initially, the annual quota was set at 1% of the population and was rarely met due to complex regulations, including bans on shooting from motorboats and burdensome sample collection requirements. These rules were relaxed in 2023, and the 2025 hunting quota was raised to 3% of the population (187 individuals). Hunters are now encouraged to target “problematic” seals—individuals known to repeatedly attack fishing gear—rather than just any seals at large. This targeted approach aims to reduce the most disruptive animals while avoiding widespread culling. Despite the quota, the number of seals actually hunted remains low. Cultural practices on Kihnu Island support seal hunting and full utilisation of the carcass, including for meat and handicrafts. However, this remains an exception. In most of Estonia, hunted seals are either partially used or discarded, due in large part to the EU’s seal product trade ban.
The EU trade ban on seal products is a barrier to sustainable use
The EU bans the commercial trade of seal products except those sourced from indigenous communities, such as the Inuit in Canada and Greenland. Estonia, lacking such a classification, is effectively barred from selling any seal-derived goods, including meat, skins, and handicrafts. Estonian officials argue that this restriction undermines the principle of sustainable use. The grey seal, they point out, is now abundant and can be hunted under controlled conditions. The trade ban turns the carcass into waste rather than a resource, reducing the incentive for regulated and humane hunting. The ban’s origin lies in emotive campaigns against the inhumane culling of seal pups, which Estonia neither practices nor permits. There is growing pressure to reform the regulation to allow trade in non-pup products from sustainable Baltic hunts.
Unlike cormorants, which are migratory and present across Europe, grey seals are largely confined to the Baltic. While they constitute a nuisance for fishers across the Baltic, it is in the northern Baltic that their numbers have exploded, with the population in Estonia roughly double the 3,000-4,000 individuals needed for good status. For cormorants, Estonia supports the development of a pan-European management plan, recognising that national actions can be undermined by cross-border migration. A coordinated effort, currently being drafted by EIFAAC (the European Inland Fisheries and Aquaculture Advisory Commission, an FAO body) for the European Commission, is expected to provide legal and policy backing for national management plans. Estonia anticipates that this will strengthen its position in future legal challenges and encourage similar measures in neighbouring countries. For seals, a Baltic-specific management approach is being advocated. Countries like Sweden and Finland already implement more extensive seal hunting programmes, and regional coordination could lead to more coherent strategies that balance conservation with fisheries sustainability.
Successful predator management calls for widespread backing
Estonia’s experience illustrates the complex interplay between wildlife conservation, fisheries management, and rural economies. Cormorants and grey seals, once indicators of ecological recovery, have become pressing management concerns. The state has responded with science-based, legally sanctioned interventions aimed at reducing the damage to fish stocks and fishing livelihoods. However, the success of these measures hinges on broader support—from EU regulatory reform to regional cooperation and public acceptance. Without this, local fishers may find themselves bearing the burden of conservation success, even as their own livelihoods hang in the balance.