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Watz, J. (2019). Climbing the ladder: an evaluation of three different anguillid eel climbing substrata and placement of upstream passage solutions at migration barriers. Animal Conservation, 1-11
Open this publication in new window or tab >>Climbing the ladder: an evaluation of three different anguillid eel climbing substrata and placement of upstream passage solutions at migration barriers
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2019 (English)In: Animal Conservation, ISSN 1367-9430, E-ISSN 1469-1795, p. 1-11Article in journal (Refereed) Epub ahead of print
Abstract [en]

Conservation programmes for endangered, long-lived and migratory species often have to target multiple life stages. The bottlenecks associated with the survival of juvenile anguillid eels migrating into inland waters, the survival and growth of the freshwater life stage, as well as the recruitment and survival of silver eels, migrating back to the ocean to spawn, must be resolved. In this study, we focus on the efficiency of passage solutions for upstream migrating juveniles. Such solutions can consist of inclined ramps lined with wetted climbing substrata. We evaluated different commonly used substrata in a controlled experiment, recorded eel behaviour at the entrance of the ramp with infrared videography and validated the experimental results at a hydropower dam, where we also investigated the effects of ramp placement on performance. In the experiment on eel substratum selection, 40 % of the eels passed in lanes with studded substratum, whereas only 21 and 5 % passed using open weave and bristle substrata, respectively. Video analysis revealed that the studded substratum attracted more approaches and initiated climbs than the other substrata, but once a climb had been initiated, passage success rates did not differ between substrata. Eels using the studded substratum climbed 26 % faster than those using the bristle substratum and almost four times as fast as those climbing in the open weave. The superior performance of the studded substratum was supported by data from the field validation. Moreover, ramps positioned by the bank with low water velocities caught the most eels, but proximity to the dam had no effect on performance. To strengthen the European eel population, more juveniles need to reach their freshwater feeding grounds. A critical step to achieve this increase is to equip upstream passage solutions with suitable substrata and to optimize ramp placement at migration obstacles.

Place, publisher, year, edition, pages
John Wiley & Sons, 2019
Keywords
anguillid, fishway, hydropower, migration, recruitment, passage solutions, migration obstacles
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-71418 (URN)10.1111/acv.12485 (DOI)
Funder
Swedish Research Council Formas, 2015-824
Available from: 2019-03-04 Created: 2019-03-04 Last updated: 2019-03-21Bibliographically approved
Tamario, C., Calles, O., Watz, J., Nilsson, P. A. & Degerman, E. (2019). Coastal river connectivity and the distribution of ascending juvenile European eel (Anguilla anguilla L.): Implications for conservation strategies regarding fish-passage solutions. Aquatic conservation, 29(4), 612-622
Open this publication in new window or tab >>Coastal river connectivity and the distribution of ascending juvenile European eel (Anguilla anguilla L.): Implications for conservation strategies regarding fish-passage solutions
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2019 (English)In: Aquatic conservation, ISSN 1052-7613, E-ISSN 1099-0755, Vol. 29, no 4, p. 612-622Article in journal (Refereed) Published
Abstract [en]

Many diadromous fish populations are declining and at risk of collapse. Lack of river connectivity is a major contributor to these declines, as free migration routes between marine and freshwater habitats are crucial for life-history completion. For the conservation and ultimately recovery of such species, it is imperative that remedial measures aimed at increasing connectivity are effective. This study investigated the distribution patterns of ascending juvenile European eel (Anguilla anguilla L.) in rivers in south-western Sweden, with a focus on the effects of barriers and measures that aim to reduce the impact of barriers, i.e. fish-passage solutions (FPSs). Eel occurrence data were spatially and temporally integrated with the national databases of dams and FPSs in a Geographic Information System (GIS) environment to evaluate their effect on ascending eel distribution. The types of barriers assessed were: (i) dams with nature-like fishways; (ii) dams with eel ramps; (iii) dams with technical fishways; and (iv) dams without FPSs. Dams fitted with eel ramps or technical fishways, as well as dams without FPSs, produced a significant negative effect on the probability of eel occurrence upstream. This negative effect was not found for dams fitted with nature-like fishways, indicating that these solutions may function better than the other FPS types in this study. The probability of eel occurrence decreased with distance from the sea and increased with area sampled, number of electrofishing runs, water temperature, and with the size of the bottom substrate. We suggest that future conservation strategies for improving the natural immigration of juvenile eels should include optimizing FPS function (e.g. placement and design), the continued maintenance of FPSs, the construction of nature-like fishways, and preferably the removal of dams, which will also benefit the downstream migration of maturing eels as well as restoring other ecosystem services.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2019
Keywords
Barriers, dams, dispersal, eel ladders, eel management, electrofishing, fish passage, fishways, ramps
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-72118 (URN)10.1002/aqc.3064 (DOI)000465962300010 ()
Available from: 2019-05-23 Created: 2019-05-23 Last updated: 2019-06-13Bibliographically approved
Nyqvist, D., Elghagen, J., Heiss, M. & Calles, O. (2018). An angled rack with a bypass and a nature-like fishway pass Atlantic salmon smolts downstream at a hydropower dam. Marine and Freshwater Research, 69(12), 1894-1904
Open this publication in new window or tab >>An angled rack with a bypass and a nature-like fishway pass Atlantic salmon smolts downstream at a hydropower dam
2018 (English)In: Marine and Freshwater Research, ISSN 1323-1650, E-ISSN 1448-6059, Vol. 69, no 12, p. 1894-1904Article in journal (Refereed) Published
Abstract [en]

Hydropower dams disrupt longitudinal connectivity and cause fragmentation of river systems, which has led to declines in migratory fish species. Atlantic salmon smolts rely on intact longitudinal connectivity to move downstream from rearing habitats in freshwater to feeding grounds at sea. Smolts often suffer increased mortality and delays when they encounter hydropower plants during their downstream migration. Currently, there are few examples of downstream passage solutions that allow safe and timely passage. We assessed the performance of two passage solutions at a hydropower dam, namely, an angled 15-mm rack with a bypass and a large nature-like fishway. The performance of these new fish passage solutions was evaluated by tracking radio-tagged Atlantic salmon smolts as they encountered the facilities. The radio-tagged smolts passed the dam 9.5 h after release (median) and exhibited a dam-passage efficiency of 84%, with passage rates increasing with body length. Fish passage occurred through both the rack bypass and the nature-like fishway. The passage efficiencies were 70-95% for the rack bypass and 47% for the nature-like fisway. The new fish passage facilities resulted in improved passage conditions at the site, confirming that angled racks with bypasses as best-practise solutions for downstream passage, but also that large nature-like fishways may act as downstream passage routes for salmon.

Place, publisher, year, edition, pages
CSIRO, 2018
Keywords
downstream passage, fish passage solution, migration, passage efficiency.
National Category
Biological Sciences
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-70349 (URN)10.1071/MF18065 (DOI)000451437700011 ()2-s2.0-85055562911 (Scopus ID)
Available from: 2018-11-29 Created: 2018-11-29 Last updated: 2018-12-20Bibliographically approved
Watz, J., Nilsson, P. A., Degerman, E., Tamario, C. & Calles, O. (2018). Enhancing upstream passage solutions for juvenile eels: Effects of climbing substrate and ramp placement. In: : . Paper presented at International Conference on River Connectivity (Fish Passage 2018), 10-14 december 2018, Albury, Australia.
Open this publication in new window or tab >>Enhancing upstream passage solutions for juvenile eels: Effects of climbing substrate and ramp placement
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2018 (English)Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

Juvenile anguillid eels migrating into inland waters often face migration barriers. Upstream passage solutions normally consist of inclined ramps lined with a wetted climbing substrate. In this study, we compared the performance of three commonly used substrate types in a controlled experiment, using European eel as the test species. We also analyzed climbing behavior with videography and validated the experimental results under natural conditions at a hydropower plant. In addition, we investigated the effects of ramp placement. Studded substrate attracted more approaches and climbs and passed more eels at a higher climbing velocity than open weave and bristle substrates, results that were confirmed by the field validation. Moreover, ramps placed in the tailrace caught more eels in low than in high water velocities. To conserve anguillid eels, both safe routes for downstream-migrating adult silver eels and improved recruitment at the freshwater feeding life stage must be achieved. Optimizing ramp position and equipping upstream passage solutions with functioning climbing substrate are key factors to enhance the performance of eel ramps.

National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-70694 (URN)
Conference
International Conference on River Connectivity (Fish Passage 2018), 10-14 december 2018, Albury, Australia
Available from: 2019-01-11 Created: 2019-01-11 Last updated: 2019-01-31Bibliographically approved
Szabo-Meszaros, M., Navaratnam, C. U., Aberle, J., Silva, A. T., Forseth, T., Calles, O., . . . Alfredsen, K. (2018). Experimental hydraulics on fish-friendly trash-racks: an ecological approach. Ecological Engineering: The Journal of Ecotechnology, 113, 11-20
Open this publication in new window or tab >>Experimental hydraulics on fish-friendly trash-racks: an ecological approach
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2018 (English)In: Ecological Engineering: The Journal of Ecotechnology, ISSN 0925-8574, E-ISSN 1872-6992, Vol. 113, p. 11-20Article in journal (Refereed) Published
Abstract [en]

The obstruction of fish migratory routes by hydroelectric facilities is worldwide one of the major threats to freshwater fishes. During downstream migration, fish may be injured or killed on the trash-racks or in the hydropower turbines. Fish-friendly trash-racks that combine both ecological and technical requirements are a solution to mitigate fish mortality at a low operational cost. This study presents results from an experimental investigation of head-losses and the hydrodynamic performance of six angled trash-rack types with 15 mm bar spacing, varying bar-setup (vertical-streamwise, vertical-angled and horizontal bars) and bar profiles (rectangular and drop shape) under steady flow conditions. The trash-racks were positioned at 30 degrees to the wall of the flume and combined with a bypass at their downstream end. The impact of the different trash-rack types on the upstream flow field was characterized using Image based Volumetric 3-component Velocimetry (V3V) and at the bypass-entrance using an Acoustic Doppler Velocimeter (ADV). The results show that trash-racks with vertical-streamwise and horizontal oriented bars with drop-shape profiles have similar head-losses (13% difference), while trash-racks with vertical-angled bars provide 3-8 times larger head-losses compared to the remaining configurations. The velocity measurements showed that the highest flow velocities occurred for configurations with vertical-angled bars (0.67 m s(-1) and 0.81 m s(-1) on average, respectively). Turbulence related parameters (e.g. Reynolds shear stresses and Turbulent kinetic energy) were also investigated to evaluate the performance of the alternative trash-racks from both, engineering and ecological perspectives.

National Category
Biological Sciences
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-66708 (URN)10.1016/j.ecoleng.2017.12.032 (DOI)000426093400002 ()
Available from: 2018-03-15 Created: 2018-03-15 Last updated: 2018-05-24Bibliographically approved
Watz, J., Calles, O., Carlsson, N., Teemu, C., Huusko, A., Jörgen, J., . . . Nyqvist, D. (2018). Wood addition in the hatchery and river environments affectspost-releaseperformance of overwintering brown trout. Freshwater Biology, 64(1), 71-80
Open this publication in new window or tab >>Wood addition in the hatchery and river environments affectspost-releaseperformance of overwintering brown trout
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2018 (English)In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 64, no 1, p. 71-80Article in journal (Refereed) Published
Abstract [en]

1. Habitat structural complexity affects the behaviour and physiology of individuals,and responses to the environment can be immediate or influence performancelater in life through delayed effects.

2. Here, we investigated how structural enrichment, both pre-release in the hatcheryrearing environment and post-release in the wild, influenced winter growthand site fidelity of brown trout stocked into side channels of a regulated river.

3. Experiencing structural enrichment in the rearing environment during 3 months inautumn had no pre-release effect on growth, but a delayed positive effect afterrelease during the subsequent winter. Moreover, trout recaptured in wood-treatedsections of the side channels had grown more than trout recaptured in controlsections. Wood enrichment in the side channels also increased overwinter sitefidelity.

4. These results show that adding structure during a relatively short period may altergrowth trajectories, and adding wood to side channels is a cost-effective methodto enhance winter habitat carrying capacity for juvenile salmonids in regulatedrivers.

Place, publisher, year, edition, pages
John Wiley & Sons, 2018
Keywords
growth, habitat complexity, restoration, site fidelity, stream wood
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-69976 (URN)10.1111/fwb.13195 (DOI)000453853500006 ()
Funder
Knowledge Foundation, ProSpekt 15-20160021
Available from: 2018-10-29 Created: 2018-10-29 Last updated: 2019-03-07Bibliographically approved
Nyqvist, D., McCormick, S. D., Greenberg, L., Ardren, W. R., Bergman, E., Calles, O. & Castro-Santos, T. (2017). Downstream migration and multiple dam passage by Atlantic salmon smolts. North American Journal of Fisheries Management, 4(37), 816-828
Open this publication in new window or tab >>Downstream migration and multiple dam passage by Atlantic salmon smolts
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2017 (English)In: North American Journal of Fisheries Management, ISSN 0275-5947, E-ISSN 1548-8675, Vol. 4, no 37, p. 816-828Article in journal (Refereed) Published
Abstract [en]

The purpose of this study was to investigate behavior and survival of radio-tagged wild and hatchery-reared landlocked Atlantic Salmon Salmo salar smolts as they migrated past three hydropower dams equipped with fish bypass solutions in the Winooski River, Vermont. Among hatchery-reared smolts, those released early were more likely to initiate migration and did so after less delay than those released late. Once migration was initiated, however, the late-released hatchery smolts migrated at greater speeds. Throughout the river system, hatchery-reared fish performed similarly to wild fish. Dam passage rates varied between the three dams and was highest at the dam where unusually high spill levels occurred throughout the study period. Of the 50 fish that did migrate downstream, only 10% managed to reach the lake. Migration success was low despite the presence of bypass solutions, underscoring the need for evaluations of remedial measures; simply constructing a fishway is not synonymous with providing fish passage.

Place, publisher, year, edition, pages
Taylor & Francis, 2017
Keywords
SALAR SMOLTS; CHINOOK SALMON; FISH PASSAGE; JUVENILE SALMONIDS; DELAYED MORTALITY; COLUMBIA RIVER; SNAKE RIVER; HYDROPOWER SYSTEM; TRUTTA SMOLTS; K+ ATPASE
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-46900 (URN)10.1080/02755947.2017.1327900 (DOI)000407192600012 ()
Available from: 2016-10-19 Created: 2016-10-19 Last updated: 2018-09-10Bibliographically approved
Watz, J., Elghagen, J., Nilsson, P. A. & Calles, O. (2017). Evaluation of a novel mobile floating trap for collecting migrating juvenile eels, Anguilla anguilla, in rivers. Fisheries Management and Ecology, 24(6), 512-514
Open this publication in new window or tab >>Evaluation of a novel mobile floating trap for collecting migrating juvenile eels, Anguilla anguilla, in rivers
2017 (English)In: Fisheries Management and Ecology, ISSN 0969-997X, E-ISSN 1365-2400, Vol. 24, no 6, p. 512-514Article in journal (Refereed) Published
Abstract [en]

To improve the situation for the threatened European eel in regulated rivers, better methods need to be developed that more efficiently collect and transport juvenile eels past dams. In this study, a novel mobile, floating eel trap is described, and the results from an evaluation of the trap in two Swedish regulated rivers are presented. The mobile trap was designed to reduce the length of the climbing distance while maximizing the width of the entrance. The mobile trap caught more juvenile eels than a stationary eel ladder, serving as control. Furthermore, the mobility of the floating trap enables adaptive placement and thus offers managers the possibility to search for the spatial optimum for trapping efficiency.

Place, publisher, year, edition, pages
John Wiley & Sons, 2017
Keywords
eel ladder, elver, trap-and-transport
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-65233 (URN)10.1111/fme.12248 (DOI)000419209500010 ()
Available from: 2017-11-16 Created: 2017-11-16 Last updated: 2018-05-28Bibliographically approved
Nyqvist, D., Bergman, E., Calles, O. & Greenberg, L. (2017). Intake Approach and Dam Passage by Downstream-migrating Atlantic Salmon Kelts. Rivers Research and Applications: an international journal devoted to river research and management, 33(5), 697-706
Open this publication in new window or tab >>Intake Approach and Dam Passage by Downstream-migrating Atlantic Salmon Kelts
2017 (English)In: Rivers Research and Applications: an international journal devoted to river research and management, ISSN 1535-1459, E-ISSN 1535-1467, Vol. 33, no 5, p. 697-706Article in journal (Refereed) Published
Abstract [en]

Studying fish behaviour at hydropower dams is needed to facilitate the design and improvement of fish passage solutions, but few studies have focused on Atlantic salmon kelts. Here, we used radio telemetry (n = 40, size range = 50–81 cm) and acoustic sonar to study kelt movements in the forebay as well as their dam passage survival and subsequent migration success past multiple dams. We also compare radio telemetry and acoustic sonar observations of fish behaviour and used acoustic sonar to measure the depth distribution of fish approaching the turbine intake zone. Passage success at the dam was 41%, and mortality was largely associated with turbine passage (62%). The two fish that passed via the spill gates survived and continued their downstream migration. At the dam, all but one radio-tagged kelt approached the intake zone shortly after arrival to the forebay, and sonar data showed that approaching fish were predominantly surface oriented (72%, 88% and 96% of the observations were less than 1, 2 and 3 m deep, respectively). Turbine passage rate from the intake zone was higher at night than at day, indicating that the lack of visual cues may reduce the barrier effect of the 70-mm conventional trash rack. Turbine passage rate also increased with increasing hydropower generation. The percentage of observed upstream movements away from the intake zone compared with the total number of observations was considerably greater in the radio telemetry data (41%) than in the sonar data (4%). Only one fish survived passage of all eight hydropower dams to reach the lake. This low-passage survival underscores the need for remedial measures to increase the survival of migrating kelts, and the fish's surface orientation as well as their rapid approach to the intake rack should be taken into account when designing such measures.

Place, publisher, year, edition, pages
John Wiley & Sons, 2017
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-46902 (URN)10.1002/rra.3133 (DOI)000402840900006 ()
Note

Was published as manuscript in D. Nyquists thesis and had then the title "Intake approach and dam passage by landlocked Atlantic salmon kelts at a hydropower dam"

Available from: 2016-10-19 Created: 2016-10-19 Last updated: 2018-09-10Bibliographically approved
Nyqvist, D., Greenberg, L., Calles, O., Goerig, E., Bergman, E., Ardren, W. & Castro-Santos, T. (2017). Migratory delay leads to reduced passage success of Atlantic salmon smolts at a hydroelectric dam. Ecology of Freshwater Fish, 26(4), 707-718
Open this publication in new window or tab >>Migratory delay leads to reduced passage success of Atlantic salmon smolts at a hydroelectric dam
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2017 (English)In: Ecology of Freshwater Fish, ISSN 0906-6691, E-ISSN 1600-0633, Vol. 26, no 4, p. 707-718Article in journal (Refereed) Published
Abstract [en]

Passage of fish through hydropower dams is associated with mortality, delay, increased energy expenditure and migratory failure for migrating fish and the need for remedial measures for both upstream and downstream migration is widely recognised. A functional fish passage must ensure safe and timely passage routes that a substantial portion of migrating fish will use. Passage solutions must address not only the number or percentage of fish that successfully pass a barrier, but also the time it takes to pass. Here, we used radiotelemetry to study the functionality of a fish bypass for downstream-migrating wild-caught and hatchery-released Atlantic salmon smolts. We used time-to-event analysis to model the influence of fish characteristics and environmental variables on the rates of a series of events associated with dam passage. Among the modelled events were approach rate to the bypass entry zone, retention rates in both the forebay and the entry zone and passage rates. Despite repeated attempts, only 65% of the tagged fish present in the forebay passed the dam. Fish passed via the bypass (33%), via spill (18%) and via turbines (15%). Discharge was positively related to approach, passage and retention rates. We did not detect any differences between wild and hatchery fish. Even though individual fish visited the forebay and the entry zone on multiple occasions, most fish passed during the first exposures to these zones. This study underscores the importance of timeliness to passage success and the usefulness of time-to-event analysis for understanding factors governing passage performance.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2017
Keywords
downstream passage, fish passage, landlocked salmon, Salmo salar, smolt migration, nedströmspassage, fiskpassage, smolt, lax
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-46897 (URN)10.1111/eff.12318 (DOI)000409505000019 ()
Available from: 2016-10-19 Created: 2016-10-19 Last updated: 2018-09-10Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-8738-8815

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