Michal Tušer

Michal Tušer
Biology Centre CAS · Institute of Hydrobiology

PhD

About

55
Publications
9,343
Reads
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840
Citations
Introduction
I am a hydrobiologist interested in (1) fish ecology in various environments and (2) greenhouse-gases fluxes in freshwaters, primarily using advanced underwater acoustic technology. I have a great deal of experiences with fisheries active and passive netting, electrofishing, and field sampling of diffusive and ebullitive fluxes of carbonic gases.
Additional affiliations
January 2021 - present
Biology Centre CAS
Position
  • Research Assistant
September 2020 - December 2020
Leibniz-Institute of Freshwater Ecology and Inland Fisheries
Position
  • PostDoc Position
January 2016 - April 2020
Biology Centre CAS
Position
  • Researcher
Education
January 2008 - June 2013

Publications

Publications (55)
Article
Full-text available
Gillnetting is a technique commonly used in relative abundance and biomass estimates of fish. However, due to its passive nature, the direct recalculation of the catch to reservoir volume or area is not trivial. This issue is often solved by using hydroacoustics, which provides information about fish density, though without the ability to distingui...
Preprint
Full-text available
To understand the conditions of coexistence in multiple-species predator community, we studied longitudinal and vertical movement of pike (Esox lucius), pikeperch (Sander lucioperca) and catfish (Silurus glanis) in the Rimov Reservoir, using an autonomous telemetry system for 11 months. We found significant differences among these three species in...
Article
Obtaining a representative sample is fundamental to the assessment of fish communities. In this study we used data from 99 different surveys of 29 artificial lakes in the Czech Republic to evaluate the precision of fish community indicator estimates based on reduced gillnet scenarios derived from triplet gillnets installed in each particular locali...
Article
Information about fish distribution and abundance in the upper part of the water column are often fundamental for both research and management. However, this information is extremely hard to obtain using conventional hydroacoustic methods. For this reason, the mobile hydroacoustic upward-looking system (38 kHz split-beam echosounder) in combination...
Article
Full-text available
DIDSON acoustic cameras provide a way to collect temporally dense, high-resolution imaging data, similar to videos. Detection of fish targets on those videos takes place in a manual or semi-automated manner, typically assisted by specialised software. Exploiting the visual nature of the recordings, tools and techniques from the field of computer vi...
Article
Full-text available
Covering an area of approximately 97 km2 and with a maximum depth of 58 m, Lake Trichonis is the largest and one of the deepest natural lakes in Greece. As such, it constitutes an important ecosystem and freshwater reserve at the regional scale, whose qualitative and quantitative properties ought to be monitored. Depth is a crucial parameter, as it...
Article
Full-text available
Fish stock monitoring is an important element for the sustainable management of inland water resources. A scarcity of data and the lack of systematic monitoring for Lake Trichonis precludes an up-to-date assessment. To assess the current status of pelagic fish stock, a hydroacousting survey was conducted for the first time in Lake Trichonis, Greece...
Article
Fish otoliths are conservative structures that are widely used on fishery science for multiple purposes. Despite its relevance in the research field, little is known about the ontogeny and inter-population effects on the otolith of freshwater fish. In this study we used otoliths from 1800 European perch (Perca fluviatilis) individuals from 9 differ...
Article
Full-text available
In this study, a remote sensing-based method of mapping and predicting fish spatial distribution in inland waters is developed. A combination of Earth Observation data, in-situ measurements, and hydroacoustics is used to relate fish biomass distribution and water-quality parameters along the longitudinal transect of thě Rímov Reservoir (Czech Repub...
Article
The effect of target strength oscillations, generated by surface or bottom-induced sound multi-pathing, can cause serious errors in estimates of fish biomass in horizontal acoustic surveys of extremely shallow inland waters (depth 1.7–2 m). In this study, the oscillations were shown to occur in both windy and calm weather conditions, and depended o...
Article
Full-text available
Chaoborus larvae inhabit frequently the water column of lakes, when they can be mistaken for small fish. Because larvae ascend up to the blind zone of downward-looking echo sounding at night, quantitative acoustic estimation of them is possible only with upwardlooking approach. For this reason, the mobile hydroacoustic upward-looking system (120 an...
Article
We conducted multiple small (2011–2012) and one large sampling campaign (2013) at selected profiles along the Elbe River. With the data we were able to outline spatial and temporal variability of methane concentration, oxidation and emissions in one of the major rivers of Central Europe. The highest methane concentrations were found in human-altere...
Article
Full-text available
Chaoborus larvae inhabit frequently the water column of lakes, when they can be mistaken for small fish. Because larvae ascend up to the blind zone of downward-looking echo sounding at night, quantitative acoustic estimation of them is possible only with upward-looking approach. For this reason, the mobile hydroacoustic upward-looking system (120 a...
Article
Full-text available
The higher proportion of males of the invasive round goby Neogobius melanostomus in samples from two activity selective passive fishing gears compared with one activity non‐selective fishing gear in three Dutch lakes is related to higher male locomotory activity and is a sex‐dependent trait. This difference in activity reflects the different ecolog...
Article
Full-text available
We investigated the change in benthic fish communities in three artificial lakes of the Biesbosch area in the Netherlands between two time periods: before and after the invasion of round goby (Neogobius melanostomus). Native ruffe (Gymnocephalus cernua), the dominant species in benthic gillnet and littoral beach seining catches before the invasion,...
Article
Sampling of benthic fish is complicated, especially in deep inland water bodies with a structured bottom. The catches were compared of rapidly spreading round goby (Neogobius melanostomus) using small fykes nets and benthic gillnets in three artificial lakes in The Netherlands over a two year period. Round gobies were captured at all depth layers i...
Article
Full-text available
Trawling juveniles is an effective method to estimate 0+ fish assemblages in inland bodies of water. Trawlers are usually moved between bodies of water by ground transport, which restricts the size, weight and type of the equipment able to be transported, and as such do not always come equipped with machinery for trawl operation. Having to lift the...
Article
Full-text available
Understanding spatial distribution of organisms in heterogeneous environment remains one of the chief issues in ecology. Spatial organization of freshwater fish was investigated predominantly on large-scale, neglecting important local conditions and ecological processes. However, small-scale processes are of an essential importance for individual h...
Article
Full-text available
Gas ebullition of river impoundments plays an increasingly significant role, particularly in transporting methane CH4 from their sediments to the atmosphere, and contributing to the global carbon budget and global warming. Quantifying stochastic and episodic nature of gas ebullition is complicated especially when conventionally conducted by using c...
Article
Full-text available
For ethical reasons and animal welfare, it is becoming increasingly more important to carry out ecological surveys with a non-invasive approach. Information about fish distribution and abundance in the upper water column is often fundamental. However, this information is extremely hard to obtain using classical hydroacoustic methods. We developed a...
Presentation
Full-text available
Ebullitive emissions of greenhouse gases have become an increasingly important gas flux from river impoundments to the atmosphere, contributing to the global carbon budget and global warming. The dynamics of gas bubbling, however, varies with spatial and temporal scales, thereby perplexing understanding and quantification of such a process. A water...
Article
Monitoring of biota in heterogeneous ecosystems requires sampling in different habitats and across environmental gradients. The resulting multivariate community data are typically aggregated into one or several indicator values for the entire ecosystem, but the relationship between the robustness of such indicators and sampling effort, including th...
Article
Horizontally-aligned, fixed and mobile, transducers are routinely deployed at depths of 0.5-0.75 m to survey the surface layer of waterbodies for fish. However, simulations and measurements demonstrate that a smooth surface can cause serious errors in the target strength (TS) and split-beam angular position estimates. Errors in TS up to 10 dB and d...
Article
Full-text available
The assessment of ecological quality in freshwater ecosystems is a key issue in many countries, but conditions for the development of assessment methodologies are often country-specific. This study proposes a simple methodology for the assessment of the ecological potential of reservoirs based on fish communities using a dataset covering major envi...
Article
Ecological quality assessment of non-natural water bodies is, in contrast to natural systems, less developed and requires determining biological indicators that reliably reflect environmental conditions and anthropogenic pressures. This study was motivated to propose fish indicators appropriate for assessment of reservoir ecosystems in central Euro...
Article
Full-text available
Round goby is generally accepted to be a typical benthic dwelling fish species both in its native and invasive ranges. Nevertheless, mid-water night trawling in the Biesbosch reservoirs (The Netherlands) identified pelagic occurrence of invasive round goby juveniles, which is the first observation of pelagic utilization in Europe. Subsequent diet a...
Article
This study addresses fish behaviour at the mouth of a midwater trawl in two temperate reservoirs. Fish distribution and behaviour were monitored using a SIMRAD EK60 (38. kHz) split-beam echosounder with the transducer deployed at the water surface, attached to the surface trawl headrope. We were able to describe day and night patterns of vertical d...
Article
Full-text available
Data from nine reservoirs in the Czech Republic were used to investigate density and size distribution patterns for dominant fish species of the juvenile pelagic community at night. Clear trends of increasing density along the longitudinal gradient for bream, roach, bleak, and pikeperch were observed in long (>5 km) reservoirs but were absent in sh...
Article
Full-text available
Methane represents an important greenhouse gas, and its ebullition is a significant way of releasing gas from bottom sediments of shallow fresh waters to the atmosphere. Estimation of ebullition is complicated because of high spatiotemporal variability; however, a hydroacoustical survey represents an effective method for quantifying it. Commonly us...
Article
Full-text available
We investigated diel habitat use of fish covering the littoral and pelagic zones of the Římov Reservoir (Czech Republic) and analyzed the influence of predator presence and of shifting feeding habitats in all dominant species and age groups. Our sampling revealed distinctive diel changes of fish distribution in the reservoir, which were age- and sp...
Article
Full-text available
Large year-to-year variability in different fish species recruitment has been confirmed by previous studies while diurnal patterns of occupation in two basic reservoir habitats (pelagic and littoral) by different age-0 fish species in late summer are still unclear. Data collected over an 11-year period regarding late-summer age-0 fish assemblages i...
Article
Full-text available
The diel horizontal migration (DHM) of fish between the inshore and offshore zones of the Římov Reservoir (Czech Republic, deep, stratified, meso-eutrophic) was investigated by a combination of horizontal and vertical hydroacoustic surveys at 3-h intervals over 48 h and day/night purse seining in August 2007. An overwhelming majority of fish were a...
Article
In lentic freshwater systems, vertical acoustics may underestimate fish abundance in the acoustic dead zone where fish detection capability is limited. To estimate this bias, the height of fish above the lead-line of a benthic multi-mesh gillnet (1.5 m high) was used to quantify both the vertical distribution of fish near the bottom and the proport...
Article
The aim of this study was to test the selectivity of a trawl main body, especially for small fish, during night sampling. The tested trawl had a mesh size of 80/40/20 mm in the main body, a mouth opening of approximately 100 m2, and a length of 48 m and was originally designed for sampling vendace, Coregonus albula L. Trawl selectivity was determin...
Article
Observing and quantifying fish behaviour towards active sampling gears like trawls is challenging. A high-frequency imaging sonar (DIDSON) was applied to directly observe and record fish avoidance behaviour in front of the mouth of an active pelagic surface trawl in the meso- to eutrophic Czech reservoir Želivka in August 2009. In this multi-specie...
Article
Inland water bodies contain extremely steep-sloped bottoms compared with those typically occurring during marine vertical surveys. These steep bottom slopes can cause high acoustic dead zones, biasing our estimates of living organisms. The studies so far have used the assumption that the first contact between the acoustic wavefront and bottom will...
Conference Paper
Direct observation of fish avoidance behaviour with respect to an active pelagic trawl is challenging. A DIDSON acoustic camera was used for direct observation of the fish avoidance behaviour in front of the mouth of an active pelagic surface trawl in the mesotrophic Czech reservoir Zelivka. Based on their reaction and swimming behaviour towards th...
Article
Abstract  Diel changes in littoral fish assemblage were studied in four reservoirs in the Czech Republic (Central Europe). The sampling was performed by beach seining in an unstructured littoral zone. Perch, Perca fluviatilis L., roach, Rutilus rutilus (L.), bream, Abramis brama (L.), carp, Cyprinus carpio L., ruffe, Gymnocephalus cernua (L.), pike...
Article
In July 2008, early juvenile tubenose goby Proterorhinus semilunaris were found in nocturnal pelagic waters of the Vranov Reservoir, Czech Republic. Presence of benthic-living prey in the guts of these fish suggested migration between benthic and pelagic habitats.
Article
Full-text available
The community of pelagic fish fry present during late summer was studied in the canyon-shaped and eutrophic Římov Reservoir, Czech Republic, using nighttime trawling over seven years. Cyprinid fish dominated in the open water area throughout the period investigated. The highest mean density of fry in the surface water layer was observed in 1999 (15...
Article
Abstract –  Spatial distribution of the fish community in the deep canyon-shaped Římov Reservoir, Czech Republic, was studied using overnight gillnetting fishing in 1999–2007. Effects of depth, distance from the dam to the tributary and habitat type (benthic and pelagic) on fish community structure, catch per unit of effort (CPUE), biomass per unit...
Article
Abstract  The inshore fish community of the Římov Reservoir in the Czech Republic was evaluated over 21 years using shore seining at night. The development of the fish community was divided into two separate phases: a highly dynamic and unstable phase dominated by perch, Perca fluviatilis L., was replaced by an extremely stable cyprinid phase domin...
Article
The orientation of fish in a horizontal plane has important consequences for estimating their true size from horizontal acoustic records. The aim of this work was to verify the assumption that during the daytime fish are randomly orientated in the lacustrine zone of the canyon-shaped Římov reservoir and to compare distributions of fish orientation...
Article
Full-text available
Day and night acoustic surveys were used to compare fish stock estimates at eight European reservoirs and one flooded mining pit. During both photoperiods of summer, higher fish biomass was observed in the uppermost 4 m of the water column by horizontal beaming than in deeper water by vertical beaming. Comparisons of volume backscattering coefficie...
Article
Full-text available
The aim of this study was to quantify the efficiency of different lengths of beach seine nets for each diel period in freshwater reservoirs. Only fish older than young-of-the-year were considered. Nets of 10, 20 and 50 m length ("in-nets") were tested in an enclosed area framed by a 200 m long net (block net). The net efficiency estimate was calcul...
Article
Full-text available
Spatial distributions of fish were studied in two types of reservoirs by means of hydroacoustics during the summer. Different patterns of fish distribution were found in non-cascade (Římov, Želivka) and cascade (Kamýk, Slapy, Štěchovice, Vrané) reservoirs. Maximum biomass and density of fish were observed in the tributary area of the non-cascade re...
Article
Full-text available
In August 2004 and 2005, an extensive study of the fish community was carried out in the largest water supply reservoir in the Czech Republic and Central Europe, the canyon-shaped Želivka Reservoir, using a fleet of Nordic multimesh gillnets. Fishes were sampled at eight locations along the longitudinal profile of the reservoir and at five benthic...

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Project (1)
Project
The aim of the project is to select suitable location and develop mobile migration barrier above the Lipno reservoir. The barrier must not influence either the river flow or transport of debris, but have to effectively prevent reservoir fish from migrating into upper Vltava river catchment.