The impact of fishing on biodiversity

Preventing excessive catching pressure is the key task of fisheries regulation


BALTIC HERRING. Baltic herring and sprat are the fish species caught the most in Estonia.
BALTIC HERRING. Baltic herring and sprat are the fish species caught the most in Estonia.


The strategic goal of fishery is to ensure the good status of fish populations and the diversity of fish species. It is important to avoid the negative effects of fishing on the ecosystem, for example by not catching undersized specimens. It is important to ensure that fish habitats are not damaged or that spawning peace is not disturbed. In addition, as many fish migrate extensively throughout their lives, both between freshwater and sea areas and within freshwater bodies, it is important to ensure that fish routes are not blocked by dams or (illegal) fishing gear. The fish stock is in good condition if the populations have a natural age structure and are able to reproduce naturally under the existing conditions.


Fishing is not the only factor


In addition to fishing, the state of fish stocks is also affected by the state of water bodies. While fish in Estonian lakes usually do well, the condition of many watercourses still needs to be improved. Disruption of the natural flow of water is often a problem: dams or other obstructions on rivers prevent many fish species from accessing suitable spawning or revitalising grounds. Fortunately, the situation is improving, as dams are being actively opened in Estonia and many concerns have already been resolved. A good example is the Sindi dam on the Pärnu River. With the elimination of the dam and the construction of artificial rapids, salmon and several other fish were given the opportunity to gain access to numerous spawning grounds of the Pärnu river system, which were previously inaccessible due to the dam. Eliminating the barrier to migration is the best way to ensure the free movement of fish, and the establishment of nature-friendly fish gates can also be considered a good option.


In addition to improving the condition of inland waters, efforts must continue to ensure the good health of the Baltic Sea. The situation of our home sea is not commendable, which is why the countries around the Baltic Sea have set themselves the common goal of achieving the good condition of the sea. The main concern is the eutrophication of the Baltic Sea due to the excessive release of nutrients and pollutants into the sea. The nutrients are phosphorus and nitrogen compounds, which, for example, in the case of excessive fertilisation in agriculture, are washed away with rainwater from the fields into the rivers and from there to the sea. Over-nutrition can lead to algal blooms and reduced water transparency and oxygen content, which, in turn, affects the functioning of the aquatic ecosystem and food chains, including the ability of fish to cope in the environment (e.g. whitefish populations are disappearing/extinct in many places because of this). Pollutants are, for example, drug residues that cannot be completely removed in wastewater treatment plants. At some point in time and place, fish stocks may be under excessive catching pressure and therefore change the assessment of the state of the sea to worse. Efforts are made to prevent (and, if necessary, reverse) the putting of fish stocks under excessive catching pressure through the implementation of the principles of sustainable fisheries management.


In order to restore or strengthen the endangered fish populations, people reproduce fish stocks in fish farms, i.e. the offspring of endangered fish populations are raised in fish farms to be introduced into water bodies as they become juveniles. Populations are stimulated until they have reached stability and do not need external support. In Estonia, fish populations are reproduced by the Põlula fish farm of the State Forest Management Centre (RMK). Salmon and whitefish are mainly farmed and introduced this way, attempts are also made with grayling, and in previous years, one of the main species in need of this additional help was the brown trout. Today, brown trout no longer needs to be introduced into the rivers of Northern Estonia, and salmon populations in most open rivers of Northern Estonia do not need additional support in the form of introduction either. Instead, the focus will be on supporting the next populations in need, such as the various subspecies of the whitefish.


Fisheries regulation


In order to conserve and sustainably exploit fish stocks, most commercial sea/ocean fishing is internationally regulated. European fisheries started to be managed at EU level in the 1980s, when the problem of overfishing became more widely acknowledged.


When calculating the fishing capacities of the Baltic Sea, a distinction is made between migratory and non-migratory fish. The exploitation rates for migratory fish species (sprat, Baltic herring, cod, salmon) are set by the Council of the European Union; less migratory fish species (e.g. perch, zander) are managed by each country separately. Fishing opportunities and conditions for Lakes Peipsi, Lämmijärv, and Pihkva are agreed on in the fisheries commission between the governments of Estonia and Russia.



Last modified: 17.02.2021