| 1. |
- Aldvén, David, 1986, et al.
(författare)
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Migration speed, routes, and mortality rates of anadromous brown trout Salmo trutta during outward migration through a complex coastal habitat
- 2015
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Ingår i: Marine Ecology Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 541, s. 151-163
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Tidskriftsartikel (refereegranskat)abstract
- Little is known about migratory routes and habitat use of anadromous brown trout Salmo trutta at sea. We therefore conducted a 2 yr study (2011-2012) on sea trout in the River Himlean system (a river, an estuary, and a coastal sea environment) in western Sweden. The main objectives were to investigate migration speed, migration routes, and mortality both for adult brown trout returning to the sea (kelts) and smolts (generally 2 yr old trout migrating to the sea for the first time). Brown trout were captured and tagged with hydro-acoustic transmitters, after which they were released and monitored during their initial migration. Migration was primarily nocturnal in the river and estuary, whereas no tendency for nocturnal migration was observed along the coast. Migration speed tended to decrease as individuals progressed from the river through the estuary and along the coast, and we found no differences in absolute migration speed between kelts and smolts. Smolts and kelts showed similar mortality. Mortality during the initial part of the migration ranged between 5 and 51% and was significantly higher in 2011, for both smolts and kelts. Our study is the first to compare migratory patterns and mortality rates between sea trout kelts and smolts during the transition from freshwater into an open coastal system.
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| 5. |
- Kagervall, Anders, et al.
(författare)
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Linking habitat characteristics with juvenile density to quantify Salmo salar and Salmo trutta smolt production in the river Savaran, Sweden
- 2010
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Ingår i: Fisheries Management and Ecology. - : Wiley. - 0969-997X .- 1365-2400. ; 17, s. 446-453
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Tidskriftsartikel (refereegranskat)abstract
- P>Habitat mapping along 85 km of river was related to juvenile (15 years of electric fishing) and smolt (3 years of screw-trapping) abundance data to estimate salmon, Salmo salar L., and sea trout, Salmo trutta L., smolt production in the River Savaran, northern Sweden. Spawning site selection by radio-tagged salmon (n = 12) and sea trout (n = 4) was also assessed. Fifty-one hectares of potential spawning and nursery habitat was found in the main stem river, representing 25% of the total river area. These areas were estimated to yield 1300-7580 salmon and 630-3540 sea trout smolts based on juvenile densities, equating with 3 years of screw-trap data (2990-5080 salmon and 680-2520 trout smolts, respectively). A hypothetical maximum production of about 19 900 salmon smolts was predicted for the river at a density of 40, 0+ salmon 100 m-2. Tracking adults during the spawning period identified optimal and potential reproductive areas.
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| 6. |
- Kiviloog, Jaan, 1975, et al.
(författare)
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EN STUDIE AV SMOLTVANDRING MED RADIOTELEMETRI OCH STRÖMNINGSMODELLERING
- 2004
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Ingår i: Proceedings Hidroenergía 04, Falkenberg, Sweden.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A study on the effect of the flow field on downstream migration of smolts in a major northern Swedish river (Umeälv) is presented. The study comprises telemetric studies of downstream migrating smolts and three-dimensional computational fluid dynamics (CFD) studies of the flow. The CFD studies are validated with velocity data from field measurements with an Acoustic Doppler Profiler (ADP). The objective of this study is to determine the migration paths of salmon and trout smolts and relate these paths to the flow field. The results from the study can be used to improve smolt survival by taking appropriate measures to divert smolts from the turbines, e.g. by changing spill rules or installing bypass systems. Results from this telemetry show that the smolts move along the main stream of the river. Since this data only yield information on the smolt positions on a 2-dimensional plane it cannot directly be concluded whether the smolt migration is passive or active. Acomparison of the downstream migration speed of fish with the water velocities in the upper water column indicates that the downstream migration is passive.
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| 7. |
- Kiviloog, Jaan, 1975, et al.
(författare)
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Hydraulic modelling and validation for the study of smolt migration
- 2004
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- In order to assess the prerequisites for downstream migration of smolt the flow field upstream two hydropower stations in two large Swedish rivers have been made, and the simulations have been validated against stream velocities measured on site. The validated models have been used to compare the flow paths with the measured swimming paths of smolts. The simulations were done by solving the three dimensional Reynolds-averaged Navier-Stokes equations using the Fluent computational fluid dynamics (CFD) package. One of the studied rivers, Ume älv, whose main course is completely regulated, has a large unregulated tributary river, Vindelälven, which holds important spawning grounds for salmon (Salmo salar) and trout (Salmo trutta), and downstream of the confluence of the two rivers there is only one hydropower plant, the Stornorrfors power plant. This constitutes a major hindrance for fish migrating between the Bothnian Sea and the spawning grounds of the river Vindelälven. The juvenile fish, smolt, leaving the Vindelälven downstream towards the ocean can migrate either through the turbines and deep rock tunnels of the power plant or through the surface weirs at the regulating dam. Because of the flow regime during the migration period of smolts most smolts are believed to follow the main stream through the turbines leading to a mortality of approximately 25 %. The other studied river, Pite älv, also contain some spawning grounds in smaller tributaries upstream its first power plant. Although this plant is more like a-run-of-the-river plant most smolt passes the turbines instead of going over the spillways.The objective of the study is to determine the migration paths of salmon and trout smolts and relate their behaviour to hydraulic factors. The results from the study could then be used to improve smolt survival by taking appropriate measures to divert the smolts from the turbines, e.g. by changing spill rules or installing diversion systems.In Ume älv in Spring 2002, 22 salmon and 22 trout smolts were tagged with internal, individually coded radio transmitters (ATS). After the release approximately five kilometres upstream of the dam at Stornorrfors power plant their passages were registered at three stationary recorders and their movements tracked manually in the horizontal plane along their swimming paths. Simultaneously, velocity profiles were measured in selected cross-sections using an Acoustic Doppler Profiler (ADP). In spring 2003 16 smolt were tagged, released and tracked in the same way in Pite älv. In 2004 also the swimming depth was recorded.Results from the tracking, flow measurements and flow simulation indicate that the smolts move along the main stream of the river. In Ume älv the tracking data only yielded information on the smolt positions in the horizontal plane but it was found that the water velocities in the upper part of the water column along the smolts migration paths were close to the mean transport velocity of the smolt. In Pite älv Spring 2004 the swimming depth was measured to between 0.5 to 2 m below the surface. It can thus be concluded that the smolt migration is passive i.e. the smolt drift passively with the water.This study is part of a more extensive project that comprises studies of both upstream and downstream migration of fish. The objective of the project is to study the correlation between flow hydraulics and fish migratory behaviour. The ultimate goal is to create numerical fish models that are programmed to act as real fish in the CFD model. To get realistic models it is then first necessary to map real fish migratory behaviour to get to know the rules of the fish behaviour.
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| 8. |
- Kiviloog, Jaan, 1975, et al.
(författare)
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Influence of flow on migratory behaviour of salmon smolts
- 2003
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Ingår i: Proceedings, Hydro 2003, Cavtat, Croatia.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- A study on the effect of flow velocity on the downstream migration of smolts, i.e. juvenile salmon and trout, in a major northern Swedish river, Ume älv, is presented. Few studies have been done on Swedish smolt migratory behaviour. This study comprises telemetric studies of downstream migrating smolts and flow velocity measurements in field. To achieve more comprehensive information about the flow field numerical simulations are carried out. This is done by solving the three dimensional Reynolds-averaged Navier-Stokes equations using the Fluent computational fluid dynamics (CFD) package. The field measurements are also used to validate the numerical flow simulation. The river Ume älv, where the study is preformed, is fully used for power production. However, its largest tributary river, Vindelälven, is unregulated and holds important spawning grounds for salmon (Salmo salar) and trout (Salmo trutta), and downstream of the confluence of the two rivers there is only one hydropower plant, the Stornorrfors power plant. This constitutes a major hindrance for fish migrating between the Bothnian Sea and the spawning grounds of the river Vindelälven. The juvenile fish leaving the Vindelälven downstream towards the ocean can migrate either through the turbines and deep rock tunnels of the power plant or through the surface weirs at the regulating dam. Because of the flow regime during the migration period of smolts most smolts are believed to follow the main stream through the turbines leading to a mortality of approximately 25 %.The objective of the study is to determine the migration paths of salmon and trout smolts and relate their behaviour to hydraulic factors. The results from the study can be used to improve smolt survival by taking appropriate measures to divert the smolts from the turbines, e.g. by changing spill rules or installing diversion systems.In spring 2002 22 salmon and 22 trout smolts were tagged with internal, individually coded radio transmitters (ATS). After the release approximately five kilometres upstream of the dam at Stornorrfors power plant their passages were registered at three plantary loggers and their movements tracked manually along their swimming paths. Simultaneously, flow velocities were measured in three dimensions using an Acoustic Doppler Profiler (ADP).Results from the tracking, flow measurements and flow simulation indicate that the smolts move along the main stream of the river. Since the tracking data only yield information on the smolt positions in the horizontal plane it cannot directly be concluded whether the smolt migration is passive or active. However, results from American studies on local salmon have shown that smolt migration occurs in the upper part of the flowing water. Combined with the fact that the water velocities in the upper part of the water column along the smolts migration paths are close to the mean transport velocity of the smolts it indicates that the downstream migration is passive.This study is part of a more extensive project that comprises studies of both upstream and downstream migration of fish. The objective of the project is to study the effect of flow hydraulics on fish migratory behaviour.
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| 10. |
- Lindberg, Magnus, et al.
(författare)
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Post-release and pre-spawning behaviour of simulated escaped adult rainbow trout Oncorhynhus mykiss in Lake ovre Fryken, Sweden
- 2009
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Ingår i: Journal of Fish Biology. - : Wiley. - 0022-1112 .- 1095-8649. ; 74, s. 691-698
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Tidskriftsartikel (refereegranskat)abstract
- Using radio telemetry, the present study simulated the escape of 48 adult rainbow trout Oncorhynchus mykiss from a net-cage fish farm in the Lake ovre Fryken, Sweden. The post-release dispersal of O. mykiss was fast, showed long-range dispersal behaviour, low winter survival and lacked the ability to find suitable spawning habitats. Thus, the present study suggested that reproducing for the first time may be an obstacle to the establishment of escaped farmed O. mykiss.
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