Around 80 fish species live in Estonian waters, do you know what they are?

Estonian waters, the Baltic Sea, Lake Peipus, rivers and wetlands, are home to some 70-80 fish species. The fish fauna developed after the last ice age and includes marine species, freshwater species and migratory fish. Human activity and climate change are increasingly affecting the distribution and abundance of fish.

Estonia is a small country, but its waters provide a surprisingly diverse habitat for fish-rich ecosystems. The Baltic Sea, Lake Peipus, Lake Võrtsjärv, numerous rivers and wetland lakes are home to an estimated 70-80 fish species, depending on whether rare vagrants and species introduced by humans are counted.

From the ice age to today

Estonia's fish fauna is relatively young; it developed after the retreat of the last ice age, when newly exposed aquatic ecosystems were gradually colonised. Thanks to the Baltic Sea's brackish waters and the connection of rivers to the sea, Estonian waters are home to both pure freshwater species and marine and migratory fish that migrate to rivers to spawn.

Given Estonia's harsh climate and low water temperatures, 70-80 species is an impressive number. Compared to tropical waters it cannot compete, but each species is an example of successful adaptation.

Who lives where?

In the Baltic Sea, whose low salinity makes it a unique habitat, you mainly encounter sprat, Estonia's national fish, as well as herring, cod and flounder. Cod abundance has dropped drastically in recent decades, but historically it was the Baltic's apex predator.

Lakes and rivers are dominated by perch, pike, roach, pikeperch and bream. Lake Peipus, one of Europe's largest inland water bodies, is particularly important; it supplies a large part of Estonia's fishing sector and is the primary habitat for pikeperch and roach.

Migratory fish travel long distances between the sea and rivers during their life cycle. In Estonia, these include salmon, sea trout, vimba and river lamprey. Salmon spawning grounds require clean, fast-flowing water, so restoring river spawning sites has become a nature conservation priority in recent years.

A chapter unto itself is the eel, Estonia's only catadromous fish, which spawns in the Sargasso Sea and whose larvae drift thousands of kilometres back to European waters. This is one of nature's greatest mysteries, which continues to astound scientists.

Alien species and human impact

Human activity has introduced to Estonian waters species that did not originally live in these ecosystems. The round goby is one of the most aggressive invaders; it is hardy, eats almost everything, and threatens the eggs and fry of native fish. The mirror carp and silver carp are also introduced species, but their role is primarily economic, being popular inhabitants of ponds and fishing grounds.

Water eutrophication, nutrient overabundance, has altered the habitats of many species. Fish species that require clear, well-oxygenated water are coming under pressure, while roach and carp can better cope in poorer conditions.

Climate change is changing the picture

Warming waters bring the spread of southerly species northwards, but cold-water-loving species are in decline. This change is already visible in Estonian waters; some species that were previously rare have become regular visitors.

Understanding Estonia's fish fauna is the basis for responsible fishing. Every angler should be able to distinguish species, understand their behaviour and know the current fishing restrictions. Detailed information can be found on the website of the Environment Agency and in the mobile app "Kalameheks" designed for recreational anglers.