| 1. |
- Abecasis, David, et al.
(författare)
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A review of acoustic telemetry in Europe and the need for a regional aquatic telemetry network
- 2018
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Ingår i: Animal Biotelemetry. - : Springer. - 2050-3385. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Background: Globally, there are a large and growing number of researchers using biotelemetry as a tool to studyaquatic animals. In Europe, this community lacks a formal network structure. The aim of this study is to review the useof acoustic telemetry in Europe and document the contribution of cross-boundary studies and inter-research groupcollaborations. Based on this, we explore the potential benefits and challenges of a network approach to identifyfuture priorities and best practices for aquatic biotelemetry research in Europe.Results: Over the past decade, there was an approximately sevenfold increase in the number of acoustic telemetrystudies published on marine and diadromous species in Europe compared to a sixfold increase globally. Over 90%of these studies were conducted on fishes and undertaken in coastal areas, estuaries, or rivers. 75% of these studieswere conducted by researchers based in one of five nations (Norway, UK, France, Portugal, and Spain) and, eventhough 34% were based on collaborations between scientists from several countries, there was only one study withan acoustic receiver array that extended beyond the borders of a single country. In recent years, acoustic telemetryin European waters has evolved from studying behavioural aspects of animals (82.2%), into more holistic approachesaddressing management-related issues (10%), tagging methods and effects (5%), and technology and data analysisdevelopment (2.8%).Conclusions: Despite the increasing number of publications and species tracked, there is a prominent lack ofplanned and structured acoustic telemetry collaborations in Europe. A formal pan-European network structure wouldpromote the development of (1) a research platform that could benefit the acoustic telemetry community throughcapacity building, (2) a centralized database, and (3) key deployment sites and studies on priority species requiringresearch in Europe. A network may increase efficiency, expand the scope of research that can be undertaken, promoteEuropean science integration, enhance the opportunities and success of acquiring research funding and, ultimately,foster regional and transatlantic collaborations. It may also help address research priorities such as the large-scalesocietal challenges arising from climate change impacts and assist the EU’s Marine Strategy Framework Directive viaidentification of good environmental status of endangered or commercially important species.
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| 2. |
- Andersson, Anders, 1980-
(författare)
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Catch and effort from a recreational trolling fishery in a large lake
- 2016
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Over recent decades recreational fisheries have grown substantially throughout the world. Despite this increase, catches from recreational fisheries have often been ignored in fisheries management, although this is now being remedied. Monitoring recreational fisheries can be expensive, and the primary means used for monitoring is angler (creel) surveys, typically funded from sales of fishing licences. The studies presented in this thesis examine different approaches to monitoring recreational trolling fisheries’ catch and effort, where fishing licenses are not required and there are no reporting requirements. I present results from a complemented roving/mail-in survey undertaken during 2013-2014 to estimate recreational effort and catch of Atlantic salmon (Salmo salar) and brown trout (S. trutta) in the largest lake in the European Union, Lake Vänern, Sweden. I also evaluate different angler catch reporting methods (mail-in, tournament reports and face-to-face interviews) and compare catch rates within and among spring and fall fishing periods. In addition, mail-in survey data are examined for recall bias. I estimate that 28.7 tonnes of salmon and trout combined were harvested by the recreational trolling fishery in 2014, more than the commercial and subsistence fisheries combined. Seasonal differences in both recreational effort and catch were observed. Effort, in boat hours, was significantly higher in spring than in fall. Catch rates of trout were higher in fall than in spring, but there were no seasonal differences in catches of salmon. Harvest per boat day did not differ significantly among catch reporting methods, indicating that all three methods could be useful for managers interested in harvest rates. In contrast, total and released catch per boat day differed among reporting methods, with tournament anglers catching more fish in total. Finally, there was little evidence for recall bias in mail-in surveys, indicating that mail-in surveys are useful for collecting unbiased catch data. My study is the most comprehensive angler survey to date for Lake Vänern, and my results should be of immediate use to local fisheries managers and should also be of interest to researchers and managers interested in estimating catch and effort for fisheries at large spatial scales.
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| 5. |
- Andersson, Anders, 1980-, et al.
(författare)
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Recreational trolling effort and catch of Atlantic salmon and brown trout in Vänern, the EU's largest lake
- 2020
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Ingår i: Fisheries Research. - : Elsevier. - 0165-7836 .- 1872-6763. ; 227
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Tidskriftsartikel (refereegranskat)abstract
- Recreational fishing has grown substantially worldwide; for some recreational fisheries both catch and economic value now exceeds that of commercial fisheries. Monitoring of recreational fisheries effort and catch is therefore important for sustainable fisheries management. We developed and implemented an angler survey to estimate effort and catch for the recreational trolling fishery for landlocked Atlantic salmon (Salmo salar) and brown trout (S. trutta) in Lake Vänern, Sweden. Major challenges were the large spatial scale and dispersed fishing effort, a lack of revenue from fishing licence sales, and a lack of catch reporting requirements. We developed a complemented roving/mail-in survey to estimate effort and catch during the main fishing periods, spring and fall, 2014. Instantaneous counts from major access sites were used for effort estimates, and mail-in surveys were used for catch rates. Our results show that Vänern supports a salmon and trout fishery of some 28.7 ± 3.3 tonnes per year. Fishing effort was higher in the spring than in the fall, and there were seasonal differences in catch rates for trout but not for salmon. Estimates show that the recreational trolling fishery now harvests more salmon and trout annually than do the commercial and subsistence fisheries combined. This highlights the importance of continuing an angler survey program for Vänern as a key element for sustainable fisheries management, and can serve as a model for other recreational fisheries at large spatial scales.
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| 12. |
- Bergman, Eva, 1959-, et al.
(författare)
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Lax och öring i Klarälven - möjligheter för vild fisk och kvalité på odlad fisk : Slutrapport 2008-2012
- 2013
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Data från 1800-talet visar att fångsterna av lax och öring i både älv och sjö varit mycket högre än idag. Storskaliga dämmen, kraftigt fiske i Dejeforsen, nio kraftverk i den svenska delen av Klarälvens huvudfåra, och användandet av älven för timmerflottning har bidragit till detta. Efter att utsättning av kompensationsodlad fisk startade ökade fångsten igen, även om den fortfarande är låg.Fältundersökningar av vild laxsmolt visade att 16 % av smolten klarade sig hela vägen förbi de åtta kraftverken mellan Edebäck och Forshaga. Under studien var vattenföringen, och därmed spillet, lågt, vilket troligen bidragit till de höga förlusterna. Normalt spills det inte under hela smoltvandringsperioden, vilket är olyckligt.Lax och öring uppfödda under normala odlingsförhållanden är oftast större och fetare än vild fisk. Vi födde upp lax med olika fodertyper och fodermängder. Mängden föda påverkade laxens tillväxt och smoltmognad, och lax som fått fettfattigt foder var mest ”naturlik”. Den klarade också vandringen bäst, 80 % tog sig till Vänern medan 55 % av laxen som fått normalt eller lite foder. Bara 20 % av tidigt könsmogna hanar tog sig till Vänern.Rapporten avslutas med implikationer och förslag till åtgärder och fortsatta studier.
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| 17. |
- 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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| 18. |
- Bowes, Rachel E., et al.
(författare)
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Landscape features control river's confluences water quality and tributary fish composition
- 2023
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Ingår i: Rivers Research and Applications. - : John Wiley & Sons. - 1535-1459 .- 1535-1467. ; 39:6, s. 1025-1036
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Tidskriftsartikel (refereegranskat)abstract
- Rivers networks represent hierarchical dendritic habitats within terrestrial landscapes and differences in connectivity and land use influence dispersal, and consequently biodiversity patterns. We, therefore, measured variation in water chemistry and fish abundance and related these to a number of landscape characteristics (e.g., wetland, urban, wooded, and agricultural) in the River Klaralven and its 30 permanently flowing tributaries. We hypothesized that these environmental attributes would differ between tributary and main stem habitat and that these differences would be driven by landscape attributes including land use. We found considerable intertributary variation in temperature and nutrient levels, and between the tributaries and the main stem. Generally, water temperature was lower in the tributaries, whereas nutrient levels were higher in the tributaries. The lower water temperature has implications for coldwater fishes, and we found two fishes, burbot and lamprey, associated with coldwater tributaries. We also found an inverse relationship between water quality and anthropogenic land use. Protecting tributaries with low anthropogenic impact will likely become increasingly important with ongoing global warming as they can function as thermal refugia for coldwater fishes. Hence, this study underscores the need to evaluate water courses at regional scales to identify spatial refuges and ensure connectivity.
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| 26. |
- Calles, Olle, et al.
(författare)
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Evaluation of nature-like fishways for re-establishing connectivity in fragmented salmonid populations in the River Emån
- 2005
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Ingår i: Rivers Research and Applications. - Chichester : John Wiley & Sons. - 1535-1459 .- 1535-1467. ; 21:9, s. 951-960
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Tidskriftsartikel (refereegranskat)abstract
- We evaluated the function of two nature-like fishways for re-establishing connectivity for anadromous salmonids in the regulated River Eman. Between 90 and 100% of the salmonids that entered the fishways actually passed through them, with median speeds of 180-190 m h(-1). Only 50% of the anadromous brown trout that passed the first fishway also passed the second one, indicating that the fish might have had problems locating the upstream fishway. The fishways were also observed to function as a passage for downstream post-spawning migrants. The densities of brown trout yearlings upstream of the fishways were higher in 2002, after the fishways were built, than during pre-fishway years. In control sites in other parts of the river as well as in a nearby river, no changes in yearling densities were observed. Thus, the fishways are working for upstream spawners, albeit at a recolonization rate that is slower than expected. Copyright (c) 2005 John Wiley & Sons, Ltd
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| 27. |
- 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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| 33. |
- Calles, Olle, et al.
(författare)
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Improving passage conditions for downstream moving fish at hydroelectric plants
- 2010
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Konferensbidrag (refereegranskat)abstract
- Many attempts at defragmenting regulated rivers only address the issue of upstream passage. Large sums of money are being spent on trying to solve the upstream passage problems at hydroelectric facilities, disregarding the problems experienced by both juvenile and adult anadromous fish on their way to the sea. Fish can be delayed, injured or even killed when attempting to pass hydroelectric plants (HEPs) via turbines, bypass devices, spill gates, trash gates or trash racks. Mitigation measures are increasingly employed to decrease the risk of injury to migratory fish at dams, mainly by preventing fish from entering the turbines and directing them to alternative routes with low risk of injury. Most frequently, screens are installed to prevent ingress into turbines, and in many countries this is a legislative requirement. However, the impingement of fish on the screens under high velocities can also result in significant mortality, and in some cases may negate the benefit associated with their placement.This presentation describes the background, design and evaluation of four rehabilitative measures at hydroelectric plants (HEPs) in southern Sweden. In the River Ätran low sloping racks and surface spill gates were implemented and tested for eels, trout and Atlantic salmon. In the River Emån the rehabilitative work focused on if a low-sloping rack and a surface spill gate could improve the passage conditions for anadromous trout and chub. In the River Alsterälven downstream migrating silver eels were offered spill pipes at different depths to study their depth preference.
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| 36. |
- Calles, Olle
(författare)
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Re-establishment of connectivity for fish populations in regulated rivers
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The hydropower industry has altered connectivity in many rivers during the last century. Many fish species depend on both an intact longitudinal connectivity to be able to migrate between spawning, feeding and winter habitats, and vertical connectivity for development and survival of incubating embryos and larvae in the gravel. The objective of this thesis was to examine problems and remedial measures associated with disrupted longitudinal and vertical connectivity in regulated rivers. The issue of longitudinal connectivity was studied in the River Emån by evaluating the efficiency of two nature-like fishways for anadromous brown trout. Telemetry studies showed that the combined efficiency for the two fishways in 2001-2004 was 60.5%. The passage efficiencies of both fishways were high for trout (89-100%), but also for other species such as chub, perch, tench, burbot and roach (74%). The attraction efficiencies were largely dependent on power plant operation, and generally high for the fishway situated next to the tail-race and low for the fishway situated inside the former channel. More than half of the trout spawners were also observed using the fishways for downstream passage. The densities of brown trout yearlings upstream of the fishways were higher after the fishways were built than during pre-fishway years. Smolts produced upstream of the fishways were observed migrating downstream in 2003-2005. The percentage of smolts that passed both power plants in was 51%, with losses being attributed to predation (15%), turbine-induced mortality (16%) and other reasons (18%). Turbine-induced mortality was higher (40%) at the power plant with four small Francis runners, than at the power plant with one large Kaplan runner (12%). The issue of vertical connectivity was studied in three rivers in Värmland, one unregulated, and two regulated, one of which had no minimum flow requirements. In the unregulated river, temporal patterns in hyporheic water chemistry correlated to variation in surface water chemistry and discharge as expected. In the regulated rivers, the hyporheic water chemistry showed little correlation to discharge or surface water chemistry. The intra-gravel water chemistry conditions for brown trout eggs were more favourable in the unregulated river, characterised by high oxygen levels, than in the two regulated rivers. The regulated river with no minimum flow requirements had critically low oxygen levels at the end of the incubation period.
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| 42. |
- 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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| 43. |
- Calles, Olle, et al.
(författare)
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The use of two nature-like fishways by some fish species in the Swedish River Emån
- 2007
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Ingår i: Ecology of Freshwater Fish. - Singapore : Blackwell Munksgaard. ; 16:2, s. 183-190
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Tidskriftsartikel (refereegranskat)abstract
- We studied the use of two nature-like fishways by 15 fishspecies (N ¼ 240) in the River Emån in southern Sweden. Use of the fishways for both passage and as a habitat was studied by electrofishing, trap catches and PIT telemetry. Of the 187 PIT-tagged fish, 52 individualsfrom 10 different species ascended one of the fishways for a total passage efficiency of 74%. For the five species that most frequently ascended the fishways, the passage efficiency was 100% for tench (Tinca tinca L.) and perch (Perca fluviatilis L.), 86% for chub (Leuciscus cephalus L.), 60% for burbot (Lota lota L.) and 50% for roach (Rutilus rutilus L.). Individuals that failed to pass the fishways were typically small cyprinids or speciesthat were assumed to have taken up residence in the fishways, such as juvenile brown trout (Salmo trutta L.) and burbot. The nature-like fishways have re-established longitudinal connectivity for most of the studied species and also functioned as rearing and winter habitat for a number of species
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| 48. |
- Cassing, Gunilla, 1972-
(författare)
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Deciduous tree occurrence and large herbivore browsing in multiscale perspectives
- 2009
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Aspen ( Populus tremula), rowan (Sorbus auquparia) and sallow (Salix caprea) are deciduous tree species of low economic value for forestry and contribute to biodiversity of boreal forests. The species are rare in managed forest landscapes, and severely browsed by moose. Their recruitment needs to increase to meet requirements of sustainable forestry to factors that affect occurrence need to be indentified. Paper I is an exploratory study on distribution of these species in relation to natural and cultural factors. In paper II moose browsing on saplings, in young forests and the influence of the landscape at three spatial scales: stand (8.6 ± 0.8 SE ha), winter home range of moose (10 km2) and annual home range of moose (25 km2). Presence of these rare species was depending on a multitude of factors acting at different spatial scales. The most important variables were soil quality, successional stage, and ownership at the stand scale and area of deciduous forest at the landscape scale. Moreover, saplings occurred at low densities in young forests (paper II) and most interestingly, saplings occurred most in middle-aged forests (20-80 years) and less than expected in younger forests (<20y) (Paper I). Browsing intensity on the different species corresponded with moose food preference and annual home range scale was most relevant for understanding browsing. Browsing on rowan was highest where the volume of deciduous food and overall young forest area were low. Browsing on birch increased when pine volume and mean patch size of young forest increased, whereas browsing on aspen was negatively related to the same variables. Thus, my results strengthen the idea that food selection is a scale-dependent process and that trade-offs between food and cover may exist for moose. Moreover, I conclude that the presence of deciduous species was a result mainly of soil quality, forest management intensity, landscape context and that the distribution of food for moose at landscape scales similar to or larger than their home range may be useful for predicting browsing on the stand scale. I propose that deciduous forests may be valuable predictors of regeneration potential in the forested landscape, and that understory deciduous sapling in middle-aged forests may be important to promote restoration and conservation actions.
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