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

Taxonomy and ecology of loaches (Cobitidae) in inner water bodies of Lithuania

The main objective of this work is to examine distribution of Lithuanian loaches, abundance and difference of their populations in Lithuanian inland waters, as well as factors conditioning selection of habitats, determine the taxonomic status and distinguish forms, subspecies or species. Novelty of the study: Loach has not yet been investigated in Lithuania, and earlier investigations into ichthyocenoses do not reflect the status, distribution, abundance and status of loaches. In dissertation are examined loach population status, distribution and abundance in Lithuania. The northern golden loach which is a new species for Lithuania was detected during this investigation and described and examined. The complex structure of spined loach populations is examined, which reveals the existence of now polyploidy hybrids in Lithuania. The knowledge of distribution of the golden loach is extended on a European scale. New information on biotypes of Cobitis taenia complex is presented and their biogeography is supplemented. The dissertation consists: The dissertation consists of the following chapters: Introduction, Literature Review, Material and Methods, Research Results and Discussion (consisting of 6 subchapters), Conclusions, Recommendations, References, List of Author’s Publications and Conference Abstracts. All the material is presented in 168 pages; Material and Methods, and Research Results and Discussion are presented in 103 pages. The list of references includes 137 sources. The text contains 74 figures and 21 tables

Several decades of two invasive fish species (Perccottus glenii, Pseudorasbora parva) of European concern in Lithuanian inland waters; from first appearance to current state

Following their first appearance, the invasive fishes Pseudorasbora parva and Perccottus glenii have been in Lithuania for several decades. However, until recently, information relating to their distribution and secondary spread was limited. For this reason, suitable habitats for these fish species were surveyed for their presence across the entire country. Additionally, all previously reported records on the presence of these species were summarized. Results revealed P. glenii to be widely distributed within the country with abundant populations in habitats suitable for the species. The recent distribution of P. parva is restricted to only a few water bodies. It was shown that both species are associated with human mediated transfer, while no natural dispersal of these invasive species was observed. The results of this study suggest that the invasion of Lithuanian inland waters by P. parva and P. glenii is still ongoing, and their occurrence in numerous water bodies, which are still devoid of these species, now seems probable. Demonstrated vectors of P. parva and P. glenii introductions in Lithuania highlight the importance of controlling and screening human activities related to aquaculture, recreational angling and the ornamental fish trade in order to restrict further P. glenii and P. parva expansion in this region

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

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

Number of tagged sea trout individuals (ind. 100 m-1) in the Šašuola Stream at the sites of capture and release on August-September (A), sites of recapture on October (B), and sites of recapture on November (C).

<p>Dotted lines denote position of beaver dams. X axis represents distance from river confluence divided in to 100 meter sections.</p

Fish metrics, significantly differing in downstream (D), middle stream (M) and upstream (U) sections (Kruskal-Wallis ANOVA and Mann-Whitney U-test for pair-wise comparisons; significantly differing sections are indicated in superscript).

<p>Fish metrics, significantly differing in downstream (D), middle stream (M) and upstream (U) sections (Kruskal-Wallis ANOVA and Mann-Whitney U-test for pair-wise comparisons; significantly differing sections are indicated in superscript).</p

Study area illustrating locations of beaver dams in the streams Šašuola and Plaštaka.

<p>Beaver dams, constructed in 2012 are indicated by an asterisk.</p

Density of individuals (per 100 m² area), number of species, Shannon diversity (<i>H</i>’) and evennes (<i>J</i>’) in the Šašuola and Plaštaka downstream (D), middle stream (M) and upstream (U) sections.

<p>Data is presented as mean ± SD of all electrofishing surveys.</p><p>Density of individuals (per 100 m² area), number of species, Shannon diversity (<i>H</i>’) and evennes (<i>J</i>’) in the Šašuola and Plaštaka downstream (D), middle stream (M) and upstream (U) sections.</p

Recommendations on reintroduction of crustaceans and fish, use of fish stocks, and improvement of the state of Lake Drūkšiai

According to historical data, the glacial relict higher crustaceans, Mysis relicta and Pallaseopsis quadrispinosa, as well as a plankton crustacean Limnocalanus macrurus had earlier been recorded in Lake Drüksiai. Our data and investigations of other authors evidence that these crustaceans no longer inhabit the lake. What are the prospects for the recovery of these crustaceans after restoring the natural thermal regime in Lake Drüksiai? One of the possibilities is to reintroduce these species after restoring the natural thermal regime in the lake and improving dissolved oxygen level in the hypolimnion, which would provide conditions for long-term survival and recovery of populations of these crustaceans. As reintroduction of relict species is rather costly, it is necessary to assess effectiveness of such works