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Sampling of the offshore fry fish communities of reservoirs by trawls
Jůza, Tomáš ; Kubečka, Jan ; Čech, Martin ; Draštík, Vladislav ; Jarolím, Oldřich ; Peterka, Jiří ; Vašek, Mojmír
The offshore area of six Czech reservoirs was sampled by pelagic fry trawl in late summer in 2003-2005. In Římov, Želivka, Vrané and Slapy reservoirs cyprinids dominated in offshore area. The main species here were roach, bream and bleak. In Lipno and Nýrsko reservoirs percids dominated in offshore area (Lipno-pikeperch, Nýrsko-perch). Trawling in offshore areas revealed that almost all 0+ fish were caught in the surface stratum (0-3m depth). In reservoirs where percids and cyprinids occured together, cyprinids dominated in 0-3m depth while percids usually prevailed in catches of 0+ fish from 3-6m depth. In ordinary canyon-shaped reservoir like Římov and Želivka the 0+ fish abundance decreased from the upstream end toward the dam, so the biggest abundance was in tributary area. In cascade reservoirs like Slapy and Vrané, the offshore area in tributary is almost without fish. The peak of abundance is more downstream and from this place, the trend is similiar to non-cascade reservoirs.
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Fish diversity and spatial distribution of YOY fish in Vlatava cascade reservoirs
Draštík, Vladislav ; Kubečka, Jan ; Jůza, Tomáš ; Jarolím, Oldřich ; Hladík, Milan ; Kratochvíl, Michal ; Prchalová, Marie ; Říha, Milan ; Tušer, Michal
Fish communities of YOY were studied in four cascade reservoir by beach fry-seining and fry trawling. Highest fish fry density was found in Slapy and Vrané reservoir. Lowest density was found in Kamýk and Štěchovice reservoir, two small reservoirs with shortest retention time, lowest oxygen concentration and temperature. Pelagic fish fry assemblages had much lower density than littoral assemblages and follow general fish longitudinal gradient. Littoral assemblages were more difficult to interpret due to more factors which can play important role in fish fry spatial distribution (such as bottom substrate and slope, complexity of shoreline, availability of water vegetation). Cyprinid species (bleak (.i.Alburnus alburnus./i.), roach (.i.Rutilus rutilus./i.), bream (.i.Abramis brama./i.)) prevailed in most reservoirs, only in Kamýk reservoir percid species (perch (.i.Perca fluvitilis./i.), ruffe (.i.Gymnocephalus cernua./i.)) prevailed.
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Species composition along the vertical gradietn in canyon-shaped reservoirs
Prchalová, Marie ; Kubečka, Jan
During years 2004 and 2005, vertical gradients of fish distribution within two canyon-shaped Czech water supply reservoirs (Římov, Švihov) were examined by Nordic multimesh gillnets in both pelagic and benthic habitats. In the open water, most fish were found in the upper 5 m of depth. Below this depth nearly no fish occurred. The community was represented mainly by bleak. Towards deeper parts the portion of perch increased. In benthic areas, most fish were in the upper 3 m of depth. Abundance declined to 10 m and below this depth nearly no fish were present. Perch and roach dominated the littoral community. Ruffe preferred the deeper habitats. With respect to biomanipulative removal catches, it is sufficient to fish in the upper 5 m of the open water and in the upper 3 m in the littoral of the reservoir. For getting a rough but adequate assessment of fish community, it is satisfactory to sample the upper 5 m of the open water and the upper 10 m in the benthic part of the reservoir.
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The influence of the water quality on managed ichthyocenosis in the Berounka River, 1975-2003
Pivnička, K. ; Humpl, Martin
In 1962-2004 the stepwise increase of the concentration of NO3-, NH4+, Cl-, and SO42- was found up to the end of 1980´s with their subsequent decrease; only for BOD the gradual decrease in all sites and years was observed. These environmental factors (EF) together with the fishery statistics from two fishing wards (B7 and B8) in the Berounka River near Radnice were used in RDA models for the evaluation of the variability in fish assemblage structure in relation to the given EF. The best results in both wards were obtained using model with three EF (BOD, NO3-, SO42-), next models with four (five) factors explained more variability, some EF were, however, not significant. The partial effect of carp as EF on the yield of other species was non significant in B7 and closely above the significance (p=0.036) in B8. The changes in the frequency of fish species in fishery statistics are influenced by EF; the fishery statistics can be used for the evaluation of changes in fish assemblages in the past.
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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.
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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.
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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.
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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.
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The first record of the black bullhead (Ameiurus melas) in the Třeboň district, Czech Republic
Hartvich, P. ; Lusk, Stanislav
In the Czech Republic, the occurrence of the Black bullhead, Ameiurus melas (Rafinesque, 1820) was recorded for the first time. The species occurs in some of the fishponds in the environs of Lomnice nad Lužnicí, southern Bohemia. The species was introduced unintentionally as an admixture to carp stocking material from Croatia in 2003. In the autumn of 2005, the occurrence was observed of adults as well as yearling fry, indicating that natural reproduction had taken place in some of the ponds. The water from the fishpond system is released into the Lužnice River so that there is a possibility of the species spreading over natural habitats of the river mentioned. The occurrence of this species in the fishponds in southern Bohemia tends to confirm the fact that transports of stocking fish, above all, carp but other species as well, present a real risk of unintentional introductions of non-native species and an important way of their subsequent dispersal.
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Long-term monitoring of the populations of Eudontomyzon mariae in the Račí potok brook (1998-2006)
Hanel, L. ; Lusk, Stanislav
The occurrence of the Ukrainian lamprey (Eudontomyzon mariae) in the Račí potok Brook is the only known population of this lamprey in the Czech republic. The status of the locality and population numbers of this species was followed up in 1998 through 2006. It is evident that the population size (as shown by the results of electro-fishings using invariably the same technique) is slightly increasing. Compared to 16 larvae.ha-1 in 1998, their number increased to 327 larvae.ha-1 in 2006. The abundance data were converted to the bottom surface, not only to that of suitable fine sediment deposits. In 2006, the same stream section was experimentally fished twice, and it has appeared that additional larvae were present in the second run (the increase in abundance being ca 38 %). In our opinion, the gradual increase in the population size of the Ukrainian lamprey in the Račí potok Brook is due to the recent revitalisation modifications of the brook bed.
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