Effects of hydropeaking and refuge configurations on the behaviour of cyprinids in experimental flume conditions

Doutoramento em Restauro e Gestão Fluviais (FLUVIO) - Instituto Superior de Agronomia / Faculdade de Arquitetura / Instituto Superior TécnicoFlow regime regulates the ecological integrity of river ecosystems, shaping the structure and function of fish communities. The discharge fluctuations in hydropower plants in response to peak electricity demand (i.e. hydropeaking) result in rapid flow changes in tailwaters. The continued hydropower operations produced morphological, hydraulic and water quality alterations, affecting downstream fish. Fish responses to hydropeaking range from organism to life-cycle event changes. It is challenging to establish a cause-effect relationship between flow variability and a fish response, and to propose adequate mitigation measures. In the first part of this research, a literature review was conducted to find evidence for that relationship. The review showed that flow variability can represent a stressor for fish. However, it remained unclear if the responses were maladaptive. In the second part, the effects of hydropeaking and refuges were assessed for L. bocagei in an indoor flume. A multidisciplinary approach was adopted, where fish responses were combined with a hydraulic characterization. Peak events were tested by manipulating magnitude, peak frequency and duration. The refuges were lateral (meandering and one-sided deflectors) and instream (triangular pyramids and v-shaped) structures, tested along three experimental campaigns. Glucose and lactate (secondary responses), and movement behaviour (whole-animal responses) were assessed. The flow field and fluid-body interactions were characterized by using acoustic Doppler velocimetry and an artificial lateral line probe respectively. The movement patterns of L. bocagei were diverse and not always proportional to the severity of the flow event. Lateral deflectors and v-shaped structures provided low velocity areas. However, the created flow complexity represented an additional constraint for fish, reducing their ability to find them. Flow thresholds that represented the resting state of L. bocagei were identified, and specific movement patterns were related with hydrodynamic changes. Practical recommendations for operational schemes and for the implementation of mitigation measures to hydropeaking were proposedN/

Field-based measurement of hydrodynamics associated with engineered in-channel structures: the example of fish pass assessment

The construction of fish passes has been a longstanding measure to improve river ecosystem status by ensuring the passability of weirs, dams and other in- channel structures for migratory fish. Many fish passes have a low biological effectiveness because of unsuitable hydrodynamic conditions hindering fish to rapidly detect the pass entrance. There has been a need for techniques to quantify the hydrodynamics surrounding fish pass entrances in order to identify those passes that require enhancement and to improve the design of new passes. This PhD thesis presents the development of a methodology for the rapid, spatially continuous quantification of near-pass hydrodynamics in the field. The methodology involves moving-vessel Acoustic Doppler Current Profiler (ADCP) measurements in order to quantify the 3-dimensional water velocity distribution around fish pass entrances. The approach presented in this thesis is novel because it integrates a set of techniques to make ADCP data robust against errors associated with the environmental conditions near engineered in-channel structures. These techniques provide solutions to (i) ADCP compass errors from magnetic interference, (ii) bias in water velocity data caused by spatial flow heterogeneity, (iii) the accurate ADCP positioning in locales with constrained line of sight to navigation satellites, and (iv) the accurate and cost-effective sensor deployment following pre-defined sampling strategies. The effectiveness and transferability of the methodology were evaluated at three fish pass sites covering conditions of low, medium and high discharge. The methodology outputs enabled a detailed quantitative characterisation of the fish pass attraction flow and its interaction with other hydrodynamic features. The outputs are suitable to formulate novel indicators of hydrodynamic fish pass attractiveness and they revealed the need to refine traditional fish pass design guidelines

Echoes in motion: An acoustic camera (DIDSON) as a monitoring tool in applied freshwater ecology

Aquatic environments are increasingly faced with anthropogenic impact. Rivers have been fully developed into navigable waterways resulting in a dramatic loss of habitats and longitudinal and horizontal disconnection. Human sewage polluted rivers and in addition with overfishing and a rising recreational use, most European diadromous fish species have suffered and can be graded as vulnerable. Species-conservation and re-stocking projects support to save diverse fish communities. Capable monitoring- and assessment tools are urgent, given that knowledge is the key for sustainable management. The DIDSON, a multibeam sonar, delivers video-like live images in high resolution, enabling the measurement of fish length and behavioral observations even in turbid water and by night in a non-invasive manner. It could be shown that a special application of the sonar offers potential to discriminate fish species based on their characteristic acoustic shadows. Beside the possibility to count and measure fish and to observe their behavior this provides additional valuable information in certain monitoring applications. New insights in the spawning behavior of Alosa Alosa could be revealed on a spawning site in the Garonne River, France. It could be observed that spawning events are not restricted to one couple since additional individuals join. Drifting clouds of sexual products and micro bubbles could be detected with the sonar and were consistent with the number of sound based spawning measurements (by human hearing) and thus served as an indicator for spawning activity. A mid- term application of the sonar in front of a trash rack of a hydro power plant demonstrated the potential to gain knowledge in the field of spatial ecology of fish with high temporal resolution. An hourly fish abundance raster was chosen as a measure of fish activity to intuitively illustrate alternating diel and seasonal activity patterns at a glance. Distinct patterns and migration peaks of three groups ‘fish’, ‘eels’ and ‘shoals’ could be identified. The size class potentially at risk to pass the trash rack, was faced the power production data to identify time windows of higher and lower risk of entrainment and respective fish protection requirements

Welfare Indicators for farmed Atlantic salmon: Tools for assessing fish welfare

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Welfare Indicators for farmed Atlantic salmon: tools for assessing fish welfare

Fish welfare is a key issue in commercial farming and is central to many decisions that farmers take during their daily husbandry practices and longer term production planning. It is also a prominent topic for NGO’s, animal welfare organisations and charities, regulatory bodies, policy makers and consumers. Farmers have long been interested in optimising the welfare of their animals and actively employ strategies that address fish welfare concerns and attempt to minimise threats to fish welfare. Independent third party organisations have even developed fish welfare standards and certification schemes for certain aquaculture species (e.g. RSPCA welfare standards for farmed Atlantic salmon and rainbow trout, RSPCA, 2018a, b). The topic of fish welfare has also been covered in numerous aquaculture research and review papers over the years, both from a fundamental and also applied perspective. This wealth of information and documentation can be spread over a wide range of sources that may not be easily accessible for the farmer and other end users. In many cases the wealth of information requires interpretation and re-presentation before it is suitable for use out on the farm. Once the farmer has information on fish welfare, they need to implement it in their production systems and daily husbandry practices. This can be a serious challenge as even measuring fish welfare can be challenging and the tools available for measurement may not be suitable for all species or all life stages. To assess the overall welfare status of the fish we use Welfare Indicators (WIs). Welfare indicators can either be direct animal-based (something you get from the fish), or indirect resource-based (e.g. rearing environment, infrastructure etc.). However, some WIs may be too complex or too difficult to apply on a farm. WIs that are appropriate for on-farm use are termed Operational Welfare Indicators (OWIs). WIs that can be sampled on the farms, but need to be sent to a laboratory or other remote analytical facility are termed Laboratory-based Welfare Indicators (LABWIs). There are other potential WIs that cannot currently be classified as either OWIs or LABWIs, these are mainly used in research but may be useful in the future or under specific circumstances at present. From the suite of appropriate OWIs or LABWIs available, the end user then needs to apply these to different production systems and husbandry routines. This is the goal of this handbook – to assemble a farm-friendly toolbox of fit for purpose Operational Welfare Indicators (OWIs) and Laboratory-based Welfare Indicators (LABWIs) for use out on fish farms in different production systems and husbandry routines. It also includes advice on their implementation and interpretation

Welfare Indicators for farmed Atlantic salmon : tools for assessing fish welfare

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