Summary of the Razna Lake Study and its conclusions

In 2016, following the order of the Nature Protection Administration, the establishment of the “Environmental Solutions Institute” Dr Biol. Matîsa Jagara conducted a study in Razna Lake to develop an environmental problem solving plan in Razna Lake, Razna National Park, based on the data obtained.
In the course of the study, the available historical data on the eutrophication of Lake Razna Lake, the control of fish and aquatic plants, the hydrobiology of lake, the causes of the eutrophication of Razna lake and the potential for restoration have been collected and analysed. As a result, scientifically justified recommendations have been drawn up to limit the environmental problems observed and improve the quality of water bodies, as well as the management and conservation of lake fish resources.
Main nutrientsnecessary for the functioning of the water body ecosystem is nitrogen and phosphorus. Phytoplankton and higher aquatic plants are used for its primary production. The nutrients in Razna lakes are harvested from the catchment area of the lake as a result of agricultural activity (the melioration ditches and other watercourses that carry the nutrients to the lakes), as well as the natural way from the wooded lands and precipitation. No significant increase in nutrients has been detected in the open part of the lake in 2016. However, in certain areas of the lake there is an increased amount of nutrients to be attributed to the point contamination sources at the Lipuški and Dukstigal Bay, as well as in the south-west of the lake and in the Zosna Bay.
The reduction of nutrients in the lakes is recommended to reduce nutrient intake from the Razna Lake catchment basin – to improve the operation of sewage treatment plants, to prevent direct contamination of pollution in the lake from the surrounding agricultural areas, as well as to recreational sites. It is recommended to connect as many homes and villages as possible to central sewage treatment plants.
Cane there is a relatively small role in the food chain of lake. Consequently, no management activity for canes is necessary from the point of view of the lake ecosystem. However, it is possible to plan strategic cane mowing to increase the recreational value of lake in places that are in the immediate vicinity of populated areas, boats, bathing sites and other access sites. It is important to emphasise that the full spinning of cane in a wide area is not desirable, as they form an important habitat for waterbirds and fish during the spring and summer period. Cane mowing should not be carried out during the fish spawning period.
Phytoplankton there are microscopic algae that play a significant role in freshwater ecosystems. It is fed mainly by zooplankton (microscopic crustaceans). In the Razna Lake, there has been no increased algae flowering in 2016 on anthropogenic eutrophication. Identified syllables Gloeotrichia ecquinulata colonies are considered a recurring phenomenon rather than an increase in the eutrophication effects of anthropogenic origin in recent years. However, it is advisable to carry out annual observations and record blue algae Gloeotrichia ecquinulata the occurrence of colonies in the lake, while analysing the seasonality of the prevalence/quantity of nutrients in the lake, in order to understand the possible reasons for the occasional flowering of this bluein species in the Razna Lake.
Zooplankton is an important component of lakes ecosystems. Zooplankton organisms are a significant feed of juvenile and plankton-eating fish of all fish species. The diversity of zooplankton and biomass is currently sufficient to provide juvenile fish and planktivoric fish with feed, but it decreases in human activity – the predatory fish that regulate the number of plankton-eating fish are caught. It should be stressed that the biomass of zooplankton has decreased compared to the 50 s of the 20 th century.
Zoobenthos or invertebrate animals that live at the bottom of the lake are an important element of aquatic ecosystems. Benthos is known to be the most important food object of fish societies in Latvia and European lakes. Zoobenthos organisms, especially bivalve molluscs, are often identified as increasing scrap and crying. It can be concluded from the available data that the biomass and diversity of zoobenthos are currently sufficient to provide benthic fish with feed. However, there is a possible increase in the diversity of bivalve molluscs in a variety of seating bivalve molluscs which may also have negative effects on the fish feed base in the Razna Lake.
Lake Razna fish tears, cracks, and ravages dominate the society. The total biomass of all fish species is considered to be medium, which could be explained by the impact of intensive industrial fishing over a long period of time. This is implicitly confirmed by the age and size structure of the control gear as well as the catch statistics from 1990 to 2016. In the most intense populations of fished fish species other than the banner, small fish that have not yet reached the size of a high commercial value prevail. The results of the controls shall show the prevalence of uneven fish in the lake. Small blades, cries and rugs prevail in the coastal part. Larger sizes, cries and sharps are more common in the depth area of 2-6 m. In the depths of the depths of 6-13 m there is a strong tear, as well as a successive dominance of posters, Ķīšu and cries. In the deeper part of the lake, the water in the upper layers (0-6 m) is rare, as well as an individual of the lake broke. The study provides a characterisation of the populations of fish species of fisheries importance (tear, plaster, rash, repsis, zandart, pike).
Lake Razna water quality is a good, fish feed base for both the development of juvenile juvenile and the maintenance of adult fish populations. Razna Lake Ihtiofauna is generally assessed as human. The structure of the fish society is significantly affected by industrial fishing. Only the large specimens of the fish that predating the population for self-regulation and the maintenance of pressure on the peaceful fish populations are caught. Asaru populations are particularly affected: small-sized fish that do not consume juveniles of other fish in their feed are prevalent.
One of the most efficient methods of successful management of water is: licensed fishing system implementation. The introduction of such a system in a positive way makes it possible to increase the amount of income from the lake management. It provides an opportunity to control and monitor fishing effort, as well as to obtain information on the volume of fishermen using back-back licences. The revenue generated allows for the financing of management measures such as strengthening the control of the use of fish resources, replenishment of fish stocks and the development of fishing infrastructure.
The establishment of an angling system licensed in Razna lakes requires the interest and support of local residents, local governments and DAP. Without the participation and consent of all involved parties, the licensed angling system is not possible. The lake should be considered suitable for the establishment of such a management model. The main fish species of interest to fishermen such as pike, tear, plaster, lakes are already present. In addition to the value and interest, the improvement of the status of fish resources, which is primarily achieved by reducing the scale of industrial fishing, could be caused.
In spite of the introduction of licensed angling, it is recommended that the following steps be taken to improve the value of the lake, such as fishing destinations:

• the operator's intention and planned activities in the management of lake shall be discussed with the relevant public part (local residents, fishermen, fishermen, etc.).
• organising open discussions on the management of lakes in general and possible scenarios in the management of Razna Lake,
• to improve fishing infrastructure around the lake - build boats bases, boat launching points, access points, fishing kindles,
• systematically inform the public about the activities of the operator.

Commercial fishing the pressure on the fish resources of Lake Razna is considered high. All fish populations, particularly predatory fish, are affected, resulting in a disrupted balance between predators and peaceful fish. As one of the solutions for improving the situation of Razna lake fish stocks, the Institute for Environmental Solutions recommends considering measures to limit industrial fishing, such as the barring of nets in Saturdays, Sundays and holidays, which, in assessing experience in other lakes, would positively control the influx of fishermen; the limitation of the fishing limits of industrial networks or the prohibition of fishing in general, replacing it with the use of self-consumption or the use of traps in the network, allowing for selective fishing, thus allowing the conservation of predatory fish.
On March 21, 2017 at 13:00 Nature Protection Administration in the Nature Education Centre “Razna” (school street 3, Lipuškos, Makoņkalna parish, Rezekne municipality) organises a public information event inviting representatives of local government, fishermen and fishermen, as well as any interested party.
Dr. Biol, a representative of the “Environmental Solutions Institute”, is planned in the first part of the meeting. Matîsa Jagar's presentation of the study carried out and its results, presentation of the nature protection administration on environmental protection requirements and measures taken in Razna National Park, presentation of the national environmental service on pollution in Razna lakes. In contrast, the second part envisages open discussion, allowing everyone to express their views, share observations and recommendations for the preservation of the natural values of Razna National Park. More information on the planned measure will be announced separately.
The Nature Protection Board has prepared a summary of the Razna Lake study and its conclusions and sends it for publication in the newspaper “Rēzekne Ambassador”. The study can be consulted in full on the website of the website of the Nature Protection Administration in the themes  NADT  National Parks  Razna National Park
(https://www.daba.gov.lv/upload/File/DOC/ZIN_P_Raznas_ez_izpete_2016.pdf)
 
 
The information was prepared by: Elīna lake,
Nature Protection pārvaldes
Head of the Department of Public attiecību and Environmental Education
Phone: 26789874
elina.ezerina@daba.gov.lv
More information: Regina Indriķe
Head of the Nature Education Centre “Razna”
Tel.: 29139677
regina.indrike@daba.gov.lv