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Publications (10 of 25) Show all publications
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
Watz, J. (2018). Brown trout in ice-covered streams: effects of surface ice on anti-predator behavior and habitat use. In: : . Paper presented at The 65th Annual Meeting of the Ecological Society of Japan (ESJ65), Sapporo, Japan, March 14-18, 2018.
Open this publication in new window or tab >>Brown trout in ice-covered streams: effects of surface ice on anti-predator behavior and habitat use
2018 (English)Conference paper, Oral presentation with published abstract (Refereed)
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-66871 (URN)
Conference
The 65th Annual Meeting of the Ecological Society of Japan (ESJ65), Sapporo, Japan, March 14-18, 2018
Available from: 2018-03-28 Created: 2018-03-28 Last updated: 2018-04-05Bibliographically 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
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
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
Piccolo, J. J. & Watz, J. (2017). Foraging Behaviour of Brown Trout: A Model Species For Linking Individual Ecology to Population Dynamics? (1ed.). In: Javier Lobón-Cerviá and Nuria Sanz (Ed.), Brown Trout: Biology, Ecology and Management: (pp. 369-382). John Wiley & Sons
Open this publication in new window or tab >>Foraging Behaviour of Brown Trout: A Model Species For Linking Individual Ecology to Population Dynamics?
2017 (English)In: Brown Trout: Biology, Ecology and Management / [ed] Javier Lobón-Cerviá and Nuria Sanz, John Wiley & Sons, 2017, 1, p. 369-382Chapter in book (Refereed)
Place, publisher, year, edition, pages
John Wiley & Sons, 2017 Edition: 1
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-65011 (URN)10.1002/9781119268352.ch15 (DOI)978-1-119-26831-4 (ISBN)
Available from: 2017-10-30 Created: 2017-10-30 Last updated: 2018-09-05Bibliographically approved
Watz, J. (2017). Overwintering behaviour of stocked brown trout: effects of the rearing environment and river habitat complexity. In: 50th Anniversary Symposium of the Fisheries Society of the British Isles, Exeter, UK, 3-7 July, 2017: . Paper presented at 50th Anniversary Symposium of the Fisheries Society of the British Isles, 3–7 July 2017, University of Exeter, UK.
Open this publication in new window or tab >>Overwintering behaviour of stocked brown trout: effects of the rearing environment and river habitat complexity
2017 (English)In: 50th Anniversary Symposium of the Fisheries Society of the British Isles, Exeter, UK, 3-7 July, 2017, 2017Conference paper, Oral presentation with published abstract (Refereed)
Abstract [en]

In channelized and structurally simple temperature streams and rivers, adverse winter conditions may challenge the ability of riverine fishes to adapt in terms of their behaviour and physiology. Access to shelter is a key habitat factor that may influence overwinter survival chances and, consequently, population dynamics. In many river restoration projects, structural elements are added to the river to increase the complexity of the physical environment. When this habitat enhancement is combined with a stocking programme, the stocked fish mayadopt different behavioural strategies to cope with the winter season depending both onthe rearing environment in the hatchery and the level of habitat complexity in the river. In this study, young-of-the-year brown trout were reared in either barren or structurally enhanced tanks, and the effects of the rearing environment on resting ventilation rate (proxy for resting metabolic rate) and score in an open field test (proxy for activity) were assessed. In side channels of a Swedish regulatedriver, trout were then released at untreated control sites or at sites that were structurally enhanced by adding whole trees to the water. Throughout winter, trout were tracked on a weekly basis, and their movements as influenced by the river habitat complexity and the previous hatchery environment were analysed. The rearing environment affected resting metabolicrates and activity, which resulted in different behavioural overwintering strategies, and adding trees to the side channels increased apparent survival. These results have implications for managing river restoration projects and further studies of stream fish winter ecology.

National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-65010 (URN)
Conference
50th Anniversary Symposium of the Fisheries Society of the British Isles, 3–7 July 2017, University of Exeter, UK
Available from: 2017-10-30 Created: 2017-10-30 Last updated: 2018-06-21Bibliographically approved
Watz, J. (2017). Stress responses of juvenile brown trout under winter conditions in a laboratory stream. Hydrobiologia, 802(1), 131-140
Open this publication in new window or tab >>Stress responses of juvenile brown trout under winter conditions in a laboratory stream
2017 (English)In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 802, no 1, p. 131-140Article in journal (Refereed) Published
Abstract [en]

Winter can be a challenging period for fish in northern temperate rivers and streams, particularly in those that are channelized, structurally simple or regulated by, for instance, hydropower. In these systems, dynamic sub-surface ice formation commonly occurs and stable periods with ice cover may be short. Under these adverse conditions, access to shelters has been shown to be an important factor that influences overwinter survival, and exclusion from shelters by anchor ice may cause stress. Here, stress responses of juvenile brown trout under simulated winter conditions in an artificial stream were studied. Trout were subjected to three treatments in which the trout (1) were excluded from an instream wood shelter, simulating the effects of anchor ice, (2) had access to the shelter or (3) had surface ice cover in addition to the shelter. There was a positive correlation between ventilation frequency and plasma cortisol concentration. Trout without access to shelter had 30% higher ventilation frequency than trout with instream shelter and surface ice, but no differences in cortisol concentration or stress colour were found between the treatments. River regulation that reduces surface ice and increases anchor ice formation may lead to increased stress and consequently reduce overwinter survival rates.

Place, publisher, year, edition, pages
Springer, 2017
Keywords
Anchor ice, Colour, Cortisol, Ice cover, Salmonid, Ventilation
National Category
Zoology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-54683 (URN)10.1007/s10750-017-3246-8 (DOI)000410768100010 ()
Note

This work was funded by The Royal Swedish Academy of Agriculture and Forestry and Carl-Fredrik von Horn’s Foundation (GFS2015-0085).

Available from: 2017-05-30 Created: 2017-05-30 Last updated: 2018-11-07Bibliographically approved
Watz, J., Bergman, E., Piccolo, J. & Greenberg, L. (2016). Ice cover affects the growth of a stream-dwelling fish. Oecologia, 181(1), 299-311
Open this publication in new window or tab >>Ice cover affects the growth of a stream-dwelling fish
2016 (English)In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 181, no 1, p. 299-311Article in journal (Refereed) Published
Abstract [en]

Protection provided by shelter is important for survival and affects the time and energy budgets of animals. It has been suggested that in fresh waters at high latitudes and altitudes, surface ice during winter functions as overhead cover for fish, reducing the predation risk from terrestrial piscivores. We simulated ice cover by suspending plastic sheeting over five 30-m-long stream sections in a boreal forest stream and examined its effects on the growth and habitat use of brown trout (Salmo trutta) during winter. Trout that spent the winter under the artificial ice cover grew more than those in the control (uncovered) sections. Moreover, tracking of trout tagged with passive integrated transponders showed that in the absence of the artificial ice cover, habitat use during the day was restricted to the stream edges, often under undercut banks, whereas under the simulated ice cover condition, trout used the entire width of the stream. These results indicate that the presence of surface ice cover may improve the energetic status and broaden habitat use of stream fish during winter. It is therefore likely that reductions in the duration and extent of ice cover due to climate change will alter time and energy budgets, with potentially negative effects on fish production.

Place, publisher, year, edition, pages
Berlin Heidelberg: Springer Berlin/Heidelberg, 2016
Keywords
Climate change, Energy budget, Global warming, Salmonid, Winter
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-39125 (URN)10.1007/s00442-016-3555-z (DOI)000374564000026 ()26787075 (PubMedID)
Available from: 2016-01-25 Created: 2016-01-25 Last updated: 2017-12-06Bibliographically approved
Watz, J., Bergman, E., Calles, O., Enefalk, Å., Gustafsson, S., Hagelin, A., . . . Bror, J. (2015). Ice cover alters the behavior and stress level of brown trout Salmo trutta. Behavioral Ecology, 26(3), 820-827
Open this publication in new window or tab >>Ice cover alters the behavior and stress level of brown trout Salmo trutta
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2015 (English)In: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 26, no 3, p. 820-827Article in journal (Refereed) Published
Abstract [en]

Surface ice in rivers and lakes buffers the thermal environment and provides overhead cover, protecting aquatic animals from terrestrial predators. We tested if surface ice influenced the behavior (swimming activity, aggressive encounters, and number of food items eaten) and stress level (coloration of eyes and body) of stream-living brown trout Salmo trutta at temperatures of 3–4 °C in indoor experimental flumes. We hypothesized that an individual’s resting metabolic rate (RMR, as measured by resting ventilation rate) would affect winter behavior. Therefore, groups of 4 trout, consisting of individuals with high, low, or mixed (2 individuals each) RMR, were exposed to experimental conditions with or without ice cover. Ice cover reduced stress responses, as evaluated by body coloration. Also, trout in low RMR groups had a paler body color than those in both mixed and high RMR groups. Trout increased their swimming activity under ice cover, with the highest activity found in high RMR groups. Ice cover increased the number of aggressive encounters but did not influence the number of drifting food items taken by each group. In mixed RMR groups, however, single individuals were better able to monopolize food than in the other groups. As the presence of surface ice increases the activity level and reduces stress in stream-living trout, ice cover should influence their energy budgets and production. The results should be viewed in light of ongoing global warming that reduces the duration of ice cover, especially at high latitudes and altitudes.

Place, publisher, year, edition, pages
Oxford: Oxford University Press, 2015
Keywords
aggression, climate change, energy budget, metabolic rate, winter
National Category
Ecology
Research subject
Biology
Identifiers
urn:nbn:se:kau:diva-35931 (URN)10.1093/beheco/arv019 (DOI)000356585100024 ()
Available from: 2015-04-29 Created: 2015-04-29 Last updated: 2018-09-10Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-4417-6636

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