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- Norrgård, Johnny, 1976-, et al.
(författare)
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Effects of feeding regimes and early maturation on migratory behaviour of landlocked hatchery-reared Atlantic salmon Salmo salar smolts
- 2014
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Ingår i: Journal of Fish Biology. - : Wiley-Blackwell. - 0022-1112 .- 1095-8649. ; 85:4, s. 1060-1073
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Tidskriftsartikel (refereegranskat)abstract
- The migratory behaviour of hatchery-reared landlocked Atlantic salmon Salmo salar raised under three different feeding regimes was monitored through the lower part of the River Klarälven, Sweden. The smolts were implanted with acoustic transmitters and released into the River Klarälven, 25 km upstream of the outlet in Lake Vänern. Early mature males, which had matured the previous autumn, were also tagged and released. To monitor migration of the fish, acoustic receivers were deployed along the migratory route. The proportion of S. salar that reached Lake Vänern was significantly greater for fish fed fat-reduced feed than for fish given rations with higher fat content, regardless of ration size. Fish from the early mature male group remained in the river to a greater extent than fish from the three feeding regimes. Smolt status (degree of silvering), as visually assessed, did not differ among the feeding regime groups, and moreover, fully-silvered fish, regardless of feeding regime, migrated faster and had a greater migration success than fish with less developed smolt characteristics. Also, successful migrants had a lower condition factor than unsuccessful ones. These results indicate that the migration success of hatchery-reared S. smolts released to the wild can be enhanced by relatively simple changes in feeding regimes and by matching stocking time with smolt development.
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| 6. |
- Calles, Olle, 1974-, et al.
(författare)
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Fish Migration River Monitoring Plan
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Fish have problems passing the Afsluitdijk Dam that separates the Wadden Sea from Lake IJsselmeer. To re-establish the connectivity and thereby allow fish to pass there is an initiative to build a fishway, the Fish Migration River (FMR), at the Konwerderzand sluice complex. This report proposes a monitoring program to evaluate the functionality of the FMR, but also to monitor passage possibilities through the existing sluices. The goals of the monitoring plan are to estimate 1) The overall passage past the Afsluitdijk dam to and from Lake IJsselmeer, 2) The attraction efficiency, 3) The passage efficiency, and 4) The use of the FMR as habitat and for acclimatization for the transition into freshwater.We present an overview of previous and ongoing monitoring in the area to establish the current state of knowledge. The report also includes a presentation of available and suitable methods for a future monitoring program considering the broad spectra of target fish species, and their abundances. The proposed program includes a description of study design and available techniques and cost-estimates of the monitoring program.The proposed program will target ten species: European eel (aal), flounder (bot), three-spined stickleback (dreidoornige stekelbaars), twait shad (fint), North Sea houting (houting), river lamprey (rieverprik), smelt (spiering), Atlantic salmon (zalm), brown trout (forel) and sea lamprey (zeeprik). The monitoring program includes plans for how to capture, tag and track the study fish using the most suitable tagging techniques. Furthermore, the most optimal sites for installation of automatic data detection stations are identified.The total cost for the proposed project is 3.5 M€ and covers both investments in equipment and costs for personnel. However, if costs for investments in techniques such as RFId-stations and fish counters are excluded, the total cost is reduced to 1 M€ for a program running two years before and four years after the completion of the FMR. The program is considered sufficient to evaluate the FMR at Kornwerederzand from the most important perspectives: the overall passage efficiency and the use of the FMR as habitat.It should be noted that this report is the first step towards a full-scale monitoring program, giving insight into possible methods, study design and associated costs. The next important step will be to develop the program in more detail and to start the initial phase of the monitoring project. We predict that such activities will identify the need for, and the relevance of, a more extensive monitoring program to study the effects of the FMR on a population level and on a large geographical scale.
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| 7. |
- Calles, Olle, et al.
(författare)
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Temporal and spatial variation in quality of hyporheic water in one unregulated and two regulated boreal rivers
- 2007
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Ingår i: River Research and Applications. - Chichester : John Wiley & Sons, Ltd. ; 23:8, s. 829-842
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Tidskriftsartikel (refereegranskat)abstract
- This study describes the temporal and spatial variations in hyporheic water quality in three boreal rivers, the River Tobyälven, an unregulated river, the river Mangälven, a regulated river with a minimum discharge requirement and the river Järperudsälven, aregulated river without any minimum discharge requirements. A total of 43 permanent piezometers were used to measure dissolved oxygen (DO), temperature, electrical conductivity, pH, NO3 and NH4 in the hyporheic water at 150mm and 300mm depth, at monthly intervals from October 2001 to October 2002. Another seven piezometers were installed in brown trout redds and monitored during the incubation period, from December 2001 to April 2002. In the river Tobyälven, temporal patterns in hyporheic water chemistry correlated to variations in surface water chemistry and discharge. In the river Jäperudsälven, the hyporheic water chemistry did not correlate to discharge or surface water chemistry. In the river Mangälven, the water chemistry was dominated by releases from a large upstream lake, and there were weak correlations between surface water chemistry andhyporheic water chemistry at some sites. The incubation conditions for brown trout eggs were most favourable in the unregulated river, characterized by high DO levels that remained high throughout the incubation period. In the river Järperudsälven the DOlevels were variable during spawning, and then gradually declined to critically low levels during incubation, whereas in the river Mangälven the DO conditions were intermediate and stable. Thus we observed a stronger coupling between surface waterconditions and hyporheic conditions, i.e. vertical connectivity, in the unregulated river than in the regulated river with minimum flow requirements, which in turn was stronger than in the river without minimum flow requirements. Copyright # 2007 JohnWiley & Sons, Ltd
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| 8. |
- Voicu, Razvan, et al.
(författare)
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Caras River Gorge aspects of salmonids' communities management- technical solutions
- 2018
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Ingår i: Management of sustainable development. - : Editura Universitatii "Lucian Blaga din Sibiu". - 2066-9380 .- 2247-0220. ; 10:2, s. 5-12
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Tidskriftsartikel (refereegranskat)abstract
- There are many obstacles in rivers that prevent or hinder passage of fish past barriers. Here, we present a specially designed solution for juvenile and adult brown trout so that they may to swim past discharge-regulating weirs in the upper Caraş River in both the upstream and downstream directions. The proposed solution relies on gravity flow and will have current velocities that will not inhibit weak swimmers swimming upstream to pass the weirs. Corrosion-resistant materials and the absence of components that could potentially injure the fish will be used in the construction of these technical solutions. Although testing of the functionality of this solutions for upstream - downstream and downstream - upstream passage of weirs is needed, we believe that if implemented, it should improve connectivity especially for brown trout and consequently conserve within-stream genetic diversity in the Caraş River and where appropriate in alike other Carpathian lotic systems with similar types of weirs.
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- Österling, Martin E, 1970-, et al.
(författare)
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Habitat degradation and the decline of the threatened mussel Margaritifera maragaritifera: influence of turbidity and sedimentation on mussel an its host
- 2010
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 47:4, s. 759-768
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Tidskriftsartikel (refereegranskat)abstract
- 1. Habitat degradation is a major reason for species extinctions. For parasite–host interactions, the decline of a parasite may not only be related to the parasite’s tolerance to habitat degradation but also indirectly through the host’s tolerance to the same disturbance.2. Our objective was to explore the cause of population declines of the freshwater pearl mussel Margaritifera margaritifera by relating the age distribution, density and growth of the mussels with turbidity, sedimentation rates and density of the mussel’s host, trout Salmo trutta, in 26 Swedish streams.3. An analysis of the age structure of nine mussel populations showed that maximum age differed by 60 years, with five populations having low proportions of juvenile mussels. Adult mussel density was higher at sites where juvenile mussels occurred than at sites lacking juvenile mussels.4. Growth of adult mussels during the past 10 years was lower in the five streams lacking recent recruitment than in the four streams with recent recruitment, indicating that some environmental factor may be negatively impacting these populations.5. A comparison among 24 populations indicated that turbidity and sedimentation may be responsible for recruitment failure in 58% of the populations. The age of the youngest mussel was positively related to turbidity and sedimentation, and juvenile mussel density was negatively related to turbidity and sedimentation. In contrast, trout density was not related to recruitment of mussels or sedimentation, but was positively related to turbidity in all streams, both with and without recent mussel recruitment.6. Synthesis and applications. Recruitment failure of M. margaritifera appears to be related to its own vulnerability to turbidity and sedimentation rather than to its host’s response to this type of habitat degradation. The results from our study suggest that managers might be able to evaluate the potential viability of mussel populations by measuring stream turbidity. Restoration activities to improve the mussels’ environment should focus on reducing fine material transport into streams.
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- Bowes, Rachel E., et al.
(författare)
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Cobble substrate in a surface bypass reduces bypass acceptance by common roach Rutilus rutilus
- 2021
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Ingår i: Ecological Engineering. - : Elsevier. - 0925-8574 .- 1872-6992. ; 172
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Tidskriftsartikel (refereegranskat)abstract
- Historically, ecological engineered solutions for fish passage across anthropogenic barriers in rivers has mainly focused on facilitating upstream passage for long-migrating diadromous fish, such as salmonids. More recently, passage solutions have shifted their focus to a more holistic ecological perspective, allowing passage for species with different swimming capacity, both upstream and downstream. This experiment investigated whether the addition of cobble in the passageway of a surface bypass could facilitate downstream movement of a cyprinid fish, the common roach Rutilus rutilus. Surface bypasses were constructed in large experimental flumes and roach were released into the flumes and monitored for bypass passage using PIT-telemetry through 11-h night-trials. Behavior was scored using four continuously-recording video cameras at the bypass construction. There was a negative effect of substrate-treatment on the passage rate through the bypass. The majority of the fish in the No substrate treatment had successfully passed within 4 h, while a lesser proportion of the fish in the Substrate treatment had done so (additional fish in the latter treatment passed later in the trials). Fish exposed to cobble substrate in the bypass passageway showed more avoidance-like behaviors at the ramp section of the bypass and tended to return back upstream more often than the fish in the no-substrate control trials. When reaching the passageway, the substrate-exposed fish expressed no behaviors that could be indicative of reduced passage success, as compared to controls. We conclude that passage was not hindered by the presence of cobble substrate, but passage was delayed due to avoidance behavior at the bypass ramp when cobble substrate was present. Based on these results, the addition of cobble substrate in a surface bypass cannot be recommended as a measure to facilitate the downstream passage performance of the common roach through surface bypasses.
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