Two current members of NRRV, Larry Greenberg and Eva Bergman, and two former members, Johnny Norrgård and Pär Gustafsson, have recently published an overview of 15 years of research on the endemic, large-bodied population of landlocked River Klarälven-Lake Vänern population of Atlantic salmon (Salmo salar).

They highlight the major findings from studies of each of the salmon’s life stages and conclude that the Klarälven salmon population is below carrying capacity. Greenberg et al. (2021) suggest measures to increase the number of spawners and downstream passage success, and they also recommend habitat restoration to compensate for losses from, for example, former log-driving activities. They also discuss the ecological and legislative problems that need to be addressed if one wishes to re-establish salmon in Klarälven’s upper reaches in Norway. Managing, conserving and conducting research on this migratory salmonid population has been challenging not only because of the ecosystems’ large size, but also because there is more than one anthropomorphic stressor involved.

Read more about the paper here:

Anna Hagelin and the opponent Professor Ian Fleming, Memorial University of Newfoundland, Canada, at Anna’s PhD defense

Anna Hagelin successfully defended her PhD thesis with the title “Conservation of landlocked Atlantic salmon in a regulated river: Behaviour of migratory spawners and juveniles12 April this year.

Anna also presented her research at “forskningspodden” (the research podcast), which is a popular science podcast at Karlstad University. Here you can listen to Anna talk about her research on salmon conservation in river Klarälven (in Swedish).

Anna Hagelin’s PhD thesis nailed at the main entrance at Karlstad University.

PhD-defense: Conservation of landlocked Atlantic salmon in a regulated river

On Friday 12 April, Anna Hagelin will defend her PhD-thesis “Conservation of landlocked Atlantic salmon in a regulated river – Behaviour of migratory spawners and juveniles”. The defense will take place at 10:00 in room 1B309 (Sjöströmssalen) at Karlstad University. Everyone is welcome to attend the defense.

Ian Fleming (Memorial University of Newfoundland (Canada) will be the opponent and Jaakko Erkinaro (Natural Resources Institute, Finland), Eva Thorstad (Norwegian institute for Nature Research, Norway) and John Armstrong (Marine Scotland Science Freshwater Fisheries Laboratory, Scotland) constitute the grading committee.


Mini-symposium on Atlantic salmon

On Thursday 11 April, a mini-symposium on Atlantic salmon will be held in room 5F322 at Karlstad University, where the visiting researchers will give presentations:


Anna Hagelin nailed her thesis at the biology department at Karlstad University on Friday 22 March.

14:00-14:30: Ian Fleming, Memorial University of Newfoundland. Life-history dependent migration strategies in Atlantic salmon 

14:30-15:00: Jaakko Erkinaro, Natural Resources Institute Finland. Diversity in Atlantic salmon – evolutionary ecology and management implications 

15:00-15:30: Coffee break

15:30-16:00: Eva Thorstad, Norwegian Institute for Nature Research. Status of salmon in Norway and importance of the ocean phase 

16:00-16:30: John Armstrong, Marine Scotland Science Freshwater Fisheries Laboratory. Current and future applications of science for management of salmon in Scotland

On Tuesday 5 March (tomorrow) Anna Hagelin, PhD student at Karlstad University, will give a pre-dissertation talk titled “Conservation of landlocked Atlantic salmon in a regulated river: behaviour of migratory spawners and juveniles”. The seminar starts at 13:15 in room 5F416. Everyone is welcome to attend the seminar.

Anna will defend her doctoral thesis on 12 April at 10:00 in room 1B309 at Karlstad University. More information will come closer to the dissertation.

As part of the Gullspång salmon and -trout monitoring program, a group of people from the management group, Gammelkroppa Lax and Jyväskylä University/Fortum perform redd surveys in the river every year in early December. The salmon and trout in the Gullspång River spawn fairly late in the season, first trout in October-early November and then salmon in November until around the beginning of December.

This year I was invited to assist in the redd surveys, which I of course said yes to! Any chance to learn more about the Gullspång salmon and -trout is valuable for the model I’m making. Plus, it’s nice to get out of the office, even when the temperature is close to zero. And it’s also very inspiring to meet other people who are studying the Gullspång salmonids.


Lilla Åråsforsen. With sunrise at around 8:30 and sundown at 15:30, we had to be efficient to cover the three areas (about 6.4 hectares) in the precious daylight hours the four days.


So, we started by the Årås bay (Åråsviken) on Tuesday, and slowly worked our way upstream. With layers upon layers (upon layers…etc.) under our waders, and thick, wadded rubber gloves we walked gracefully around in the three spawning areas – Lilla & Stora Åråsforsen and Gullspångsforsen- to look for anything that could be a fish-made structure in the gravel beds. Sometimes we had redds that looked like textbook examples of redds, other times they didn’t look like anything. To confirm or disprove that it was an active redd, we did some careful digging in the pit itself to see if it contained at least two live eggs. The females often do some test diggings before the “real deal”.

We marked confirmed redds with conspicuously colored stones so that they can be found again in the spring; their location was also mapped with a GPS. Initially, we started with Finnish marking stones, but to our slight surprise they ran out (see why further down). We therefore had to settle with slightly lighter Swedish stones the last few days. Sadly, Norway was not represented with any stones (but we’ll see next year).

We also took measurements of the dimensions of the redds, as well as the depth and velocities along the gradient between start of pit and end of tail. I quickly took the role of propeller lady, taking the flow velocity measurements with NRRV’s OTT meters. It was interesting to see how much higher the velocity generally was in the tail compared to in the pit.


Horseshoe-formed tail of a large redd in Lilla Åråsforsen rapids marked with a white-painted and numbered stone. The marking stones were bought from a local stone dealer in Finland and brought to Gullspång.


I’ve saved the best for the end: the reason why we kept running out of marking stones was that we counted a record number of redds this year! We found redds also where they usually are not found, in total around 190 of them! It’s a careful victory, because we don’t yet know how many of them are salmon respective trout redds. But it was a nice early Christmas present, and I’m glad I joined!

/Kristine Lund Björnås


Learn more:

Management report on the monitoring results on Gullspång salmon and –trout in 2017:


Salmon females design their redds in a sophisticated way to increase velocities and dissolved oxygen to the egg pockets as shown with a 3D fluid dynamic model:

Tonina, D. & Buffington, J.M. (2009). Doi:10.1139/F09-146

In June 2018, The Ecology and Evolutionary Ethology of Fishes Conference was held in Montreal, Quebec, Canada. Eva Bergman and Larry Greenberg from Karlstad University attended the conference, and participated in a symposium on the ecology of landlocked Atlantic salmon. You can read the abstracts from their talks here:

Conservation of landlocked salmon and trout in a regulated river – a holistic approach

Bergman, Eva; Calles, Olle; Greenberg, Larry; Hagelin, Anna; Norrgård, Johnny; Nyqvist, Daniel; Piccolo, John J

Populations of migratory salmon and trout have worldwide shown a decline due to human activities. Over the years numerous measures have been undertaken to maintain these populations, and conservation of migratory salmonids requires understanding of their ecology at multiple scales, combined with assessing anthropogenic impacts. The regulated River Klarälven and Lake Vänern host endemic populations of landlocked Atlantic salmon (Salmo salar) and brown trout (Salmo trutta). The historically high abundances of the salmonids in the River Klarälven in the early 1800s have decreased dramatically, reaching all-time lows after the completion of nine Swedish hydroelectric power stations in the 1960s. After an extensive stocking program and transportation of spawners past eight hydroelectric plants, catches from commercial, maintenance and sport fishing have again increased. Recently, increases in the proportion of wild salmon returning to the river have generated interest in establishment of wild salmon inhabiting the entire river, including upstream of the Norwegian border where they historically occurred. How well are we equipped to meet these new goals, taking into account our limited knowledge of the species’ different life stages, coordination between different actors involved in the conservation processes, and our skills to communicate and understand everybody’s role in this conservation process?

Post-spawning survival and downstream passage of landlocked Atlantic salmon in the regulated river Klarälven

Greenberg, Larry; Bergman, Eva; Calles, Olle; Hagelin, Anna; Nyqvist, Daniel

Repeat salmonid spawners may make large contributions to total recruitment and long term population stability. Despite their potential importance, little is known about this life stage for landlocked populations. Here, we studied post-spawning behaviour and survival of landlocked Atlantic salmon in relation to downstream dam passage in the River Klarälven, Sweden from 2011-14. Eight hydropower stations separate the feeding grounds in Lake Vänern from the spawning grounds in the river, and no measures to facilitate downstream migration are present. Nearly half of the salmon survived spawning and initiated downstream migration. Females and small fish had higher post-spawning survival than males and large fish. During years with high spill, 84% of the fish passed the first dam, mostly via upward-opening spill gates after a median delay of 25 min. During a year of low spill, 41% of the fish passed the dam, mostly through the turbines, where mortality was high. In addition, most fish approached the turbine intake near the surface. For all years combined, only 2% of the tagged fish successfully passed all eight hydropower stations to reach Lake Vänern. This result underscores the need for remedial measures to increase survival of downstream migrating kelts.

Access the conference program here.

Group photo from the landlocked Atlantic salmon symposium at the Ecology and Evolutionary Ethology of Fishes (EEEF) Conference 2018

Larry Greenberg at the Lake Champlain research conference.

The Lake Champlain research conference Lake Champlain: Our future is now was held at the Davis Center, University of Vermont, in Burlington 8-9 January 2018. The conference covered a variety of topics, including climate change and native fish restoration. Larry Greenberg, professor at Karlstad University, was invited as keynote speaker at the conference and gave the talk “Conservation of landlocked Atlantic salmon in a regulated river: Taking a holistic approach.” Read more about the conference here.


Tracking smolts in Huntington River, a tributary to Winooski River.

The accepted version of the scientific article “Downstream migration and multiple dam passage by Atlantic salmon smolts” by Daniel Nyqvist (Kau), Stephen McCormick (USGS), Larry Greenberg (Kau), William Ardren (US Fish and Wildlife), Eva Bergman (Kau), Olle Calles (Kau), and Theodore Castro-Santos (USGS) is available online at North American Journal of Fisheries Management. The paper presents a study on downstream migration and dam passage of landlocked Atlantic salmon smolts in the River Winooski, a tributary to Lake Champlain.

In the abstract the authors write: “The purpose of this study was to investigate behavior and survival of radio-tagged wild- and hatchery-reared landlocked Atlantic salmon smolts as they migrated past three hydropower dams equipped with fish bypass solutions in the Winooski River, Vermont, USA. Among hatchery-released 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 released 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.”

Access the paper here or contact the authors.


The hydroelectric dam in the study. Turbine intakes and bypass entrances to the left, open spill gates to the right. Photo from Google Maps.

The paper “Migratory delay leads to reduced passage success of Atlantic salmon smolts at a hydroelectric dam” by Daniel Nyqvist (Kau), Larry Greenberg (Kau), Elsa Goerig (INRS, Quebec) , Olle Calles (Kau) , Eva Bergman (Kau), William Ardren (US Fish and Wildlife), and Theodore Castro-Santos (USGS) was recently published in the journal Ecology of Freshwater Fish. The paper presents a study on the behavior of landlocked Atlantic salmon smolts in the Winooski River in Vermont, USA.

In the abstract the authors write:“Passage of 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 recognized. 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 radio telemetry 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 modeled 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.”

Read the abstract and access the paper here. If you don’t have access to the journal’s content, email any of the authors.


Anders Andersson will defend his licentiate thesis on June 9, at 10:15 in Room 9C203 at Karlstad University.

For over two years Anders Andersson, PhD-student at Karlstad University, has been researching the catch and effort from the recreational fishery in Lake Vänern  the largest lake in the European Union. His research has focused on landlocked Atlantic Salmon and migratory brown trout. In accordance with tradition, Anders two weeks ago nailed his licentiate thesis on a wall at the university. On June 9, he will defend his thesis “Catch and effort from a recreational trolling fishery in a large lake” . Opponent will be Ian Cowx from the University of Hull, United Kingdom and the defence will take place at 10:15 in Room 9C203 at Karlstad University. 

In the abstract of the thesis, Anders writes:

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.”

Download the full licentiate thesis here.