The use of native piscivorous fishes for the eradication of the invasive Chinese Sleeper, Perccottus glenii

The chief aim of invasive species management is to prevent biological invasions by taking measures for suppressing or eradicating potential invaders. Biological control as a management tool is frequently implemented to reduce the population size, adverse ecological impacts, and dispersal of invasive species. The efficacy of biological control measures in managing the Perccottus glenii population was assessed in four small lakes of Lithuania. The biocontrol was carried out by introducing the native piscivorous fishes Esox lucius and Perca fluviatilis into the invaded water bodies for two successive reproductive seasons. The stocking of these fishes led to an instant reduction in P. glenii abundances, and the outcome of the repeated stocking was complete disappearance of the species from the water bodies investigated. Our study proves that native predator fishes can be successfully used for eradicating well-established P. glenii populations in small eutrophic lakes. We hope the current study results will contribute to developing risk-commensurate methodologies for the control of invasive P. glenii populations in small water bodies

Water Framework Directive Intercalibration: Central-Baltic Lake Fish fauna ecological assessment methods

The European Water Framework Directive (WFD) requires the national classifications of good ecological status to be harmonised through an intercalibration exercise. In this exercise, significant differences in status classification among Member States are harmonized by comparing and, if necessary, adjusting the good status boundaries of the national assessment methods. Intercalibration is performed for rivers, lakes, coastal and transitional waters, focusing on selected types of water bodies (intercalibration types), anthropogenic pressures and Biological Quality Elements. Intercalibration exercises are carried out in Geographical Intercalibration Groups - larger geographical units including Member States with similar water body types - and followed the procedure described in the WFD Common Implementation Strategy Guidance document on the intercalibration process (European Commission, 2011). The Technical report on the Water Framework Directive intercalibration describes in detail how the intercalibration exercise has been carried out for the water categories and biological quality elements. The Technical report is organized in volumes according to the water category (rivers, lakes, coastal and transitional waters), Biological Quality Element and Geographical Intercalibration group. This volume addresses the intercalibration of the Lake Central-Baltic Fish ecological assessment methods. Part A: This document comprises an overview and detailed descriptions of fish-based lake ecological assessment methods. Part B describes the construction of multiple pressure index in the Central-Baltic region. Part C describes the procedure and results of the boundary harmonisation of national fish-based lake assessment systemsJRC.D.2-Water and Marine Resource

Intercalibrating the national classifications of ecological status for very large rivers in Europe: Biological Quality Element: Phytoplankton

The European Water Framework Directive (WFD) requires the national classifications of good ecological status to be harmonised through an intercalibration exercise. In this exercise, significant differences in status classification among Member States are harmonized by comparing and, if necessary, adjusting the good status boundaries of the national assessment methods. Intercalibration is performed for rivers, lakes, coastal and transitional waters, focusing on selected types of water bodies (intercalibration types), anthropogenic pressures and Biological Quality Elements. Intercalibration exercises were carried out in Geographical Intercalibration Groups - larger geographical units including Member States with similar water body types - and followed the procedure described in the WFD Common Implementation Strategy Guidance document on the intercalibration process (European Commission, 2011). The Technical reports are organized in volumes according to the water category (rivers, lakes, coastal and transitional waters), Biological Quality Element and Geographical Intercalibration group. This volume addresses the intercalibration of the Very large river Phytoplankton ecological assessment methods. Thirteen countries (Austria, Belgium (Flanders), Bulgaria, Croatia, Czech Republic, Estonia, Germany, Hungary, Latvia, Lithuania, Poland, Romania, Slovakia) participated in the intercalibration exercise and harmonised their benthic invertebrate assessment systems. The results were approved by the WG ECOSTAT and included in the EC Decision on intercalibration (European Commission, 2018). In addition, four countries (Italy, Finland, Norway, Sweden) provided justification for excluding Phytoplankton BQE assessment system.JRC.D.2-Water and Marine Resource

Intercalibration of the national classifications of ecological status for Central-Baltic Lakes: Biological Quality Element: Fish fauna: Part B and C

The European Water Framework Directive (WFD) requires the national classifications of good ecological status to be harmonised through an intercalibration exercise. In this exercise, significant differences in status classification among Member States are harmonized by comparing and, if necessary, adjusting the good status boundaries of the national assessment methods. Intercalibration is performed for rivers, lakes, coastal and transitional waters, focusing on selected types of water bodies (intercalibration types), anthropogenic pressures and Biological Quality Elements. Intercalibration exercises are carried out in Geographical Intercalibration Groups - larger geographical units including Member States with similar water body types - and followed the procedure described in the WFD Common Implementation Strategy Guidance document on the intercalibration process (European Commission, 2011). The Technical report on the Water Framework Directive intercalibration describes in detail how the intercalibration exercise has been carried out for the water categories and biological quality elements. The Technical report is organized in volumes according to the water category (rivers, lakes, coastal and transitional waters), Biological Quality Element and Geographical Intercalibration group. This volume addresses the intercalibration of the Lake Central-Baltic Fish ecological assessment methods. This volume on intercalibration of the Lake Central Baltic Fish ecological assessment methods is split into three parts: Part A, a document that provides an overview and detailed descriptions of fish-based lake ecological assessment methods. Parts B and C: This document comprises two Parts, B and C. Part B describes the construction of multiple pressure index in the Central-Baltic region. Part C describes the procedure and results of the boundary harmonisation of national fish-based lake assessment systems.  JRC.D.2-Water and Marine Resource

Impact of Beaver Dams on Abundance and Distribution of Anadromous Salmonids in Two Lowland Streams in Lithuania

European beaver dams impeded movements of anadromous salmonids as it was established by fishing survey, fish tagging and redd counts in two lowland streams in Lithuania. Significant differences in abundancies of other litophilic fish species and evenness of representation by species in the community were detected upstream and downstream of the beaver dams. Sea trout parr marked with RFID tags passed through several successive beaver dams in upstream direction, but no tagged fish were detected above the uppermost dam. Increase in abundances of salmonid parr in the stream between the beaver dams and decrease below the dams were recorded in November, at the time of spawning of Atlantic salmon and sea trout, but no significant changes were detected in the sections upstream of the dams. After construction of several additional beaver dams in the downstream sections of the studied streams, abundance of Atlantic salmon parr downstream of the dams decreased considerably in comparison with that estimated before construction

Environmental and Socio-Economic Assessment of the Dams at the Salmonid Rivers of Lithuania

EU Biodiversity Strategy for 2030 aims to restore 25,000 km of free-flowing rivers across Europe. The critical issue is which barriers should be prioritised for removal. In this study, a set of socio-economic and environmental criteria was chosen to rank the dams on salmonid rivers in Lithuania and recommend them for removal. As these criteria usually contradict themselves, the multi-criteria decision analysis tool was utilised. The results showed that the Anykščiai dam on the river Šventoji could be recommended to be removed first. The removal can significantly increase the salmonid population in the river Šventoji over a significant stretch of the river. Also, this dam is in a protected area, is not listed as a national heritage, and does not have a hydropower plant. Although, this study showed that dams with hydropower plants could also be recommended for removal