|
|
Secundary trout zones and occurrence of grayling (Thymallus thymallus) in the territory of the Czech Republic
Halačka, Karel ; Lusk, Stanislav ; Vetešník, Lukáš
In this paper, the relationship between emergence of secondary trout zones below dams, and occurence of the grayling in the waters of the Czech Republic, is studied. The grayling was mentioned as a potentially perspective fish for our waters. This was confirmed by colossal growth of its catches in 1970s and 1980s. The space formed by creation of the secondary trout zones below series of dams, which were built at that time, was very significant for this growth. However, at the turn of the century, a breakpoint was observed, and the numbers of catches decreased to the level of the 1950s. It can be stated that these locaties appear very suitable for this species under specific conditions. However it is necessary to monitor the general dynamics of this biotope, in order to possibly establish an optimal regime fit for present organisms and therefore to form a stable equilibrium.
|
|
|
Factors affecting the species composition of fish communities inhabiting sections of the rivers Morava, Dyje, Odra and Lužnice and their adjacent floodplains
Lusk, Stanislav ; Lusková, Věra ; Lojkásek, B. ; Hartvich, P.
The species composition of fish communities was studied in sections of the rivers Morava and Dyje (Black S. basin), Odra (Baltic S.), Lužnice (North S.) with floodplains. The following factors appear to determine the species composition of the ichthyofaunae inhabiting the hydrological regions: Sea basin, location of the section in the longitudinal profile of a stream, absence of migration barriers, presence of fishponds, fishery management. As regards the origin of a community, the pertinence to a basin is of greatest importance and migration from the lower sections. As regards the species richness of ichthyofauna, the region of confluence of the rivers Morava and Dyje is the richest of the whole Czech Republic - 38 native species, 9 of which occur only in that region, 7 alien species was recorded in that region. The region of the Odra R. was found to harbour 29 native and 4 non-native species; that of the Lužnice R., 25 native and 5 non-native fish species and 1 lamprey species .
|
|
|
Large-scale rehabilitation in the alluvial area along the lower reaches of the Dyje River
Lusk, Stanislav ; Pražák, O. ; Lusková, Věra ; Halačka, Karel ; Vetešník, Lukáš
The Dyje River between Lednice and Bulhary was straightened, canalised, and provided with levees. Most of the alluvial area near Podivin was transformed to arable land. Due to elimination of floods, save for exceptions, areas denoted as wetlands and reed beds were qute dry for most of the year. As a result, the native fish communities typical of alluvial habitats gradually vanished from their habitats. In recent years, some 470 hectares on the left bank of the Dyje River, owned by a single private person, were transformed into a deer sanctuary. In the past two years, the arable land in that area has been gradually turned into meadows and a floodplain forest, together with restoring and enlarging the area of permanently waterlogged parts denoted as wetlands. As a result, the conditions permitting permanent occurrence of fish have been significantly improved and for a purposeful restoration of their fish communities in which native species predominate (the Carassius-Misgurnus type).
|
|
|
Floodplains: special measures needed for the development and stabilisation of fish biota
Lusk, Stanislav ; Hartvich, P. ; Lojkásek, B. ; Lusková, Věra ; Pražák, O. ; Halačka, Karel ; Sovíková, L.
The preserved extent of the initial floodplains along major rivers is limited and has been distinctly altered by hydrological dynamics. The results exert a negative impact on aquatic biota, above all, fishes (the floodplains of Odra, Dyje, Lužnice rivers). The most marked changes include construction of ponds, canalization of streams with levees, absence of meadow management. The consequences: absent landscape formation activity of streams, expansion of wetland vegetation, gradual silting and downfall of alluvial habitats, their total drying, destruction of elements such as channels, ditches, river arms and other habitats, a limitation or disappearance of populations of Misgurnus fossilis, Rhodeus amarus, Cobitis spp., Carassius carassius, Leucaspius delineatus. Retrieval: maintenance of optimum condition of aquatic habitats, creation of artificial wetlands, restoration populations of protected fish species. Passive protection of habitat and species is no solution any longer.
|
|
|
The mercury load in fishes inhabiting the upper section of the Divoká Orlice and Tichá Orlice rivers
Korunová, Vlasta ; Lusková, Věra ; Lusk, Stanislav
In the boundary section of Divoká Orlice R. the mercury content in the tissues of brown trout did not exceed 0.2 mg.kg-1. WHO risk limit, 1.6 µ mercury per 1 kg human body weight per week, is attained by a person weighing 75 kg and consuming 0.63 kg trout muscular tissue a week. In Divoká Orlice drainage area, the mercury content was determined in roach (Rutilus rutilus) in 1987-1995. In a majority of specimens analysed, the values of mercury contents in their muscular tissue exceeded 0.2 mg.kg-1 (max. 0.683 mg.kg-1). In the upper part of Tichá Orlice R., increased mercury contents were found in brown trout. Below the Králíky profile, the mercury contents varied around 0.50 mg.kg-1 in the muscular tissue, and up to 0.85 mg.kg-1. The mercury loads in the fishes decreased gradually in the downstream direction down to the value around 0.20 mg.kg-1. In the uppermost part of Tichá Orlice R. below the town of Králíky, the risk limit is only 0.24 kg trout meat consumed per week.
|
|
|
The fish community in the Divoká Orlice River near Kostelec nad Orlicí, and the genetic diversity of the local common gudgeon population
Mendel, Jan ; Lusková, Věra ; Lusk, Stanislav ; Halačka, Karel
The fish community was investigated in two localities (r. km 46.7 and 49.1) on the Divoká Orlice River near Kostelec nad Orlicí . Besides the species characteristic of salmonid waters (Salmo trutta, Thymalus thymallus, Phoxinus phoxinus, Cottus gobio ) there are species typical of a barbel community (Barbus barbus, Leuciscus cephalus, L. leuciscus, Gobio gobio). The occurrence of Lampetra planeri has also been recorded. The abundance attained 4,294 and 6,612 exx..; the weight, 363.8 and 509.7 kg respectively, converted to 1 hectare of water surface. The allozyme analysis of G.gobio has shown that the diversity of the population under study is average, compared to other populations examined in other streams Using the RAPD method, two identification markers have been found for the fish in the population examined. The genetic analysis of mtDNA provided a unique haplotype serving to differentiate the gudgeon population.
|
|
|
Molecular biological analyses of Sand gudgeon (Romanogobio kesslerii) in the waters of the Czech Republic and Slovakia
Mendel, Jan ; Lusk, Stanislav ; Lusková, Věra ; Koščo, J. ; Papoušek, Ivo ; Halačka, Karel ; Vetešník, Lukáš
Kessler's gudgeon belongs to critically endangered species protected by both national and European legislation. We present the first findings concerning the genetic diversity of 5 R. kesslerii populations from the Czech and Slovak rivers. On the basis of sequencing of the control region, as well as of the first intron of the S7 r-protein, 30 specimens were analysed. Altogether nine haplotypes were identified. Analyses of mtDNA showed the existence of two groups differing by 6.2%. The first group included the specimens from the rivers Bečva and Ipel and the second group included the specimens from the rivers Topl’á, Laborec and Morava. The inter-population diversity was 0.4% within the first group and it ranged from 0.5% to 1.0% within the second group. The combination of the methods of sequencing of parts of mtDNA and nDNA and allozyme analysis revealed the presence of hybrids of G. gobio and R. kesslerii in the Morava and Ipel’ rivers.
|
|
|
On the occurrence of rare and protected lamprey and fish species in the Morava River drainage area
Lusk, Stanislav ; Lusková, Věra ; Lojkásek, B. ; Halačka, Karel ; Vetešník, Lukáš ; Merta, L.
The occurrence of a considerable number of rare and protected lamprey and fish species in the Czech Republic is exclusive for the drainage area of the Morava River. Eudontomyzon mariae occurs only in the Račí potok Brook. Lampetra planeri occurs in a section ca 20 km long in the upper part of the Morava R. Romanogobio kessleri initially occurred only in the Bečva R. After 2000 was newly recorded in the Morava R. Romanogobio albipinnatus occurs in the lower reaches of the rivers Morava and Dyje; locally, we have observed in the upper parts of these rivers. After 1990 species Pelecus cultratus, Gymnocephalus schraetser, G. baloni, Zingel streber, and Z. zingel re-occurred in the confluence of Morava and Dyje rivers. The only actual range of Sabanejewia balcanica in the Czech Republic is in a short section of the Vlára R. (the Váh R. drainage area) near the boundary of Slovakia. Cobitis elongatoides occurs, in its pure form, only in the upper part of the Dyje R. drainage area.
|
|
|
Alien fish species in the Odra basin on Moravien and Silesian
Lojkásek, B. ; Lusk, Stanislav ; Papoušek, Ivo
In the territory of Moravian and Silesian, the upper part of basin of the River Odra is found, where the riverine net is formed by smaller streams. The original ichthyofauna species structure is therefore, relative poor, representing 2 lamprey and 33 fish species, from which at present, 1 lamprey and 3 fish species are considered to be extinct. During the 19th and 20th centuries within human activities, 8 alien exotic species were introduced and 5 non-native species for this area were dislocated. All introduced and dislocated species are subject to fishery management. Regards to the fact that the species Carassius carassius and Pseudorasbora parva reproduce naturally, their relationships and influence are negative to the native species, they are assessed as invasive alien species.
|
|
|
Changes in abundance of bullhead (Cottus gobio L.) in the Loučka stream near Skryje in 1968-2004
Humpl, Martin ; Lusk, Stanislav
In the site of the Loučka R., the long-term (1968-2005) monitoring has been realized, always during the autumn period. A part of the Loučka R. was selected and included in the national list of the „European important localities“ for the bullhead Cottus gobio. In the monitored section of the Loučka R., the fish community of salmonid type occurred with dominance of the species brown trout Salmo trutta m. fario, grayling Thymallus thymallus, Cottus gobio and stone loach Barbatula barbatula. The estimated abundance of the bullhead ranged from 128 to 1778 ind.ha-1, means of 504 ind.ha-1. The abundance fluctuations occurred in 10-years’ cycles. The proportion of the bullhead in the total fish abundance ranged from 4% up to 30%. The positive correlation was found between the bullhead abundance and that of grayling and stone loach. The results obtained signalise the need of care in assessing the bullhead population status in the case of less numerous and unsystematic data on abundance.
|
guest ::
