John Piccolo, researcher at Karlstad University has written a short story for the Freshwater Working Group of the Society of Conservation Biology about his work in Klarälven. Read the story at the group’s facebook page or here below:

“This is a story about some of the toughest field work I’ve carried out in over 20 years of research on salmon populations in either North America or Sweden, and describes the first documentation of a wild Atlantic salmon smolt run on the River Klarälven in central Sweden.

Klarälven is the longest river in Scandinavia, and is home to one of the world’s last remaining large-bodied landlocked Atlantic salmon (pictured) populations. The landlocked salmon migrate from Vänern, the largest lake in the EU, to spawn and rear in Klarälven (learn more about Klarälven here). After living for 2-4 years in the river, the salmon smolt migrate downstream to feed and grow in the lake. Although there has been anecdotal information about the smolt migration for many years, nobody had ever succeeded in trapping them to estimate production. Due to historical fishing pressure, and hydropower development, the Klarälven salmon are believed to be highly-threatened. However, salmon populations could also be recovering in Klarälven, because fishing pressures have reduced, and populations have gone from a low of less than 100 spawning adults to a record return of over 1000 in 2016. With this history in mind, we set out to better our understanding of salmon smolt populations in Klarälven and to guide more successful management and restoration.

A River Klarälven smolt (photo: Teemu Collin).

As many aquatic scientists know, trapping fishes or even invertebrates in rivers can be difficult – they all tend to migrate during rising or falling flows when water levels in the river are high. Keeping a net in the water can be difficult or impossible under such conditions. Months of organic debris that has been deposited along the river banks is suddenly washed into the stream, and nets need to be cleaned often, sometimes hourly 24-hours round. An additional variable in the mix is that in large rivers, organic debris can be large (picture large tree branches or even entire trees!)! High water levels, rapid flows, and large debris are challenging obstacles, and if these obstacles bring our sampling gear down, it can be quite dangerous to get the gear up and running again. I did my first smolt trapping back in 1996 on the Salmon River in Idaho, USA. I remember watching a mature conifer tree some 30 meters long being sucked into an eddy like a drinking straw, and being ejected clear out of the river on its’ way downstream. The power of a flooding river is truly awe-inspiring.

The crew working on the trap (photo: Teemu Collin).

It took us four sampling seasons, filled with trial and error, to achieve partial sampling success for our project. The first year we tried floating smolt traps like those often used for Pacific salmon. Although these can be adequate when there are large numbers of smolt migrating, we did not catch sufficient numbers of smolt to make mark-recapture estimates. During years two and three, we imported stationary traps, a Finnish design, that are anchored to the river bottom with 3-4-meter-long thick iron poles. It takes two days of hard labor for a work crew to drive these into the substrate by hand, balancing on the deck while holding the boat in position in the strong river flow (see photos). Inspired by the work to setup these Finnish traps, the title for this story comes from the classic song about mine workers – the iron bars didn’t weigh 16 tons, but just setting up the net was A LOT of work. Once the net was installed, the hard work began. Cleaning and emptying the net every day, and waiting for the spring flood to bring the salmon smolt. Although I was involved in this work, it is really our field crew that deserves most of the credit – it was a 24-hour a day, 7-day a week job, cleaning every day and staying vigilant for possible emergencies. During years two and three we came close to success – we had begun to catch larger numbers of smolt just at the time when flows became unmanageable and the net had to be removed. These years involved a lot of trial and error in operating and maintaining the net, cleaning, sewing mesh, clearing debris. The worst of it was cutting the net out during high flows, just when it seemed the smolt were beginning to run.

The Finnish trap (photo: Teemu Collin).

Each year we’d improved our technique and catch; the second year we caught over 300 smolt, and made our first rough estimates of production. However, we had yet to document a substantial wild smolt run. We managed to scrape together enough funding for one more try, and set to work for our final attempt. With two years’ experience, we installed the net in record time and had a good cleaning and maintenance routine. The field crew was on the job every day and smolt numbers began to climb as did the prognosis for the spring flood. They managed to continue to fish the net right into the beginning of the flood, and finally, on the last five days that they could fish before the flood, they hit the jackpot! SMOLTS! The field crew caught over 1000 smolt during their last five days – 425 the day before they had to remove the net. This one-week catch exceeded the total number of smolt we’d caught the previous two years combined. Our mark-recapture estimates suggest that over 15,000 wild salmon smolt migrated that year, documenting substantial production of wild landlocked Atlantic salmon, probably the largest remaining population in the world. Our hard work and persistence paid off – national and international awareness of the Klarälven salmon has continued to grow, and they are the focus of renewed efforts to maintain and restore wild salmon populations that have been impacted by centuries of anthropogenic impacts.”

Last Friday, I, Daniel Nyqvist, successfully defended my PhD-thesis “Atlantic salmon in regulated rivers – Migration, dam passage, and fish behavior” at Karlstad University. Scott Hinch (University of British Columbia, Canada) was opponent and Eva Thorstad (NINA, Norway), Kim Aarestrup (DTU AQUA, Denmark) and Hans Lundqvist (Swedish University of Agriculture) constituted the grading committee (betygskommitté). The short abstract of the thesis reads:

“Hydropower dams block migration routes, thereby posing a threat to migratory fish species. Fishways and other fish passage solutions may aid fish to pass hydropower dams. A functional fish passage solution, however, must ensure safe and timely passage for a substantial portion of the migrating fish. In this thesis, I focus on downstream passage and evaluate the behavior and survival of migrating Atlantic salmon in relation to dams in systems with (1) no fish passage solutions (2) simple passage solutions (3) best available passage solutions. In addition, I studied the survival and behavior of post-spawners and hatchery-released smolts.

A large portion of the spawners survived spawning and initiated downstream migration. For hatchery-reared smolts, early release was associated with faster initiation of migration and higher survival compared to late release. Multiple dam passage resulted in high mortality, and high spill levels were linked to high survival and short delay for downstream migrating salmon. For smolts, dam passage, even with simple passage solutions, was associated with substantial delay and mortality. Rapid passage of a large portion of the migrating adult salmon was achieved using best available passage solutions.”

The frame of the thesis is available here. Already published papers included in the thesis are Post-Spawning Survival and Downstream Passage of Landlocked Atlantic Salmon (Salmo salar) in a Regulated River: Is There Potential for Repeat Spawning? (in River Research and Applications) and Migratory delay leads to reduced passage success of Atlantic salmon smolts at a hydroelectric dam (in Ecology of Freshwater Fish). For full access to the thesis, contact daniel.nyqvist@kau.se.

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.

The scientific paper “The Migratory Behaviour and Fallback Rate of Landlocked Atlantic Salmon (Salmo salar) in a Regulated River: does Timing Matter?” by Anna Hagelin, Olle Calles, Larry Greenberg, Daniel Nyqvist and Eva Bergman was recently published in River Research and Applications. The system studied is the River Klarälven, Sweden and in the abstract the authors write:

“The behavior of early (June–July) and late (August–September) migrating, adult Atlantic salmon, in The River Klarälven, Sweden, was analyzed using radio telemetry. River Klarälven is a regulated river without functioning fishways, instead upstream migrating salmon are trapped and trucked past eight hydropower plants before released back to the river. We distinguished two parts of the spawning migration, that is, one part being the migration from the place where the fish was released to the spawning grounds. The other part was a holding phase on the spawning grounds with little or no movements before spawning. The late salmon spent less of their total time on holding, 36.2%, and more on migration, 63.8%, compared with early migrating salmon, which distributed their time rather evenly between migration, 47.5%, and holding, 52.5%. In total, early salmon used 30% more time migrating and 156% more time holding than late salmon. Some Atlantic salmon (Salmo salar) fell back over the hydropower plant after release and got excluded from spawning. The fallback rates of transported, tagged spawners were higher in the early than in the late group in both years. The fallback rate in 2012 was 42.8% of the early group and 15.1% in the late. In 2013, there were 51.7 % fallbacks in the early group and 3.4% in the late. The salmon fell back on average 9 days after being released in 2012 and 16 days in 2013. A high mean daily discharge on the day of release increased the probability of becoming a fallback”

Download the paper here. If you don’t have free access, email any of the co-authors.

A few weeks ago Stina Gustavsson and I (both PhD-students at KaU) attended a course in “Fish migration: Theory and technology” at the Tromsö University (UiT). The course was given by Eva Thorstad (NINA and UiT) and Audun Rikardsen (UiT). Topics included ecology and evolution of fish migration, methods in fish telemetry (tags and tagging) and plenty of case studies on migrating fish. Focus was on anadromous salmonids in northern Europe – Atlantic salmon, brown trout and arctic charr – and European eel, but (for example) fish migration studies in the Zambezi River and on Atlantic halibut were also discussed. Elina Halttunen, IMR also visited the course and gave a lecture on the importance of Atlantic salmon post-spawners and their downstream migration. Other attendees included Master- and PhD-students from Tromsö University (Norway), Oslo University (Norway) and DTU Aqua (Denmark). It was an interesting course with good lectures and a lot of stimulating discussions.

“Arctic charr in midnight sun”
Photo: Audun Richardsen – www.audunrikardsen.com

John Piccolo presented a poster about Klarälven salmon at the recent international symposium “Advances in the Population Ecology of Stream Salmonids – IV” in Girona, Cataluña, Spain. The poster can be seen online here:

John also gave a presentation about conservation biology of salmon and trout, focusing on a recent debate on conservation ethics summarized by Tallis et als (2014) article in Nature Communications. He also recommends Holmes Rolston IIIs “A New Environmental Ethics: The Next Millennium for Life on Earth”  for more reading on conservation ethics.

Imorgon, tisdagen den 14:e April, kommer Ian Fleming att ge ett seminarium med titeln ””Influence of environmental enrichment and transgenerational effects on salmon recovery”. Ian Flemming är till vardags verksam vid Memorial University, Kanada men är förnärvarande gästprofessor tid vid Göteborgs Universitet.

Seminariet ges klockan 13:15 i sal 5F416 på Karlstads Universitet. Alla är välkomna!

Marius Heiß, a master student who has been working by River Ätran has finished his thesis titled “Evaluation of innovative rehabilitation measures targeting downstream migrating Atlantic salmon smolt (Salmo salar) at a hydroelectric power plant in southern Sweden” . In the abstract he writes:

“The ecological state of streams and rivers has aggravated on a global scale due to a wide range of anthropogenic influences. The disruption of migratory routes for diadromous fishes by hydroelectric power plants have led to major stock declines over the last century. As a result fishways have been built at many hydroelectric power plants in Europe to improve migration conditions at such obstacles. This measure may improve upstream migration, but typically does not solve corresponding passage problems for downstream migrating fish. Consequently large numbers of downstream migrants, e.g. Atlantic salmon smolt (Salmo salar), are forced to pass turbines on their way to the ocean. There are few rehabilitation measures specifically targeting downstream passage conditions and most of them lack scientific evaluation.

This thesis reports on a radio-telemetric-study to evaluate innovative rehabilitation measures targeting downstream migrating Atlantic salmon smolt, at a hydropower plant in southern Sweden. There had been extensive renovation works at the study site to improve passage conditions for migrating fishes. The conventional turbine rack and a modified conventional trash gate were replaced by a low sloping β-rack adjacent to a full depth bypass channel. Moreover, a nature-like fishway was built at the site.
The results show that the evaluated rehabilitation measures were able to significantly improve downstream passage conditions for Atlantic salmon smolts. Total passage success was high (94%) and bypass efficiency has increased by 68%, whereas the number of smolts passing through the turbines was reduced by 63%. Although there were some issues associated with the monitoring station in the new bypass, the results are promising and so prospective constructions of low-sloping β-racks with full-depth bypasses should lead to improved downstream passage conditions at additional hydroelectric power plants.”

Read the master thesis here.

Oscar Askling, masterstudent at Karlstad University, reports on the latest progress in Daugava River:

Daugava River is the biggest river in Latvia. It originates at the Valdaja plateau and flows 1020 km through Russia, Belarus and Latvia and empties in to the Gulf of Riga in the Baltic Sea. During the hydropower cascades, from 1938 to 1974; Kegums, Plavinas and Riga Hes were built, which are today producing a great proportion of the total energy production in Latvia. However, the dams affect the longitudinal connectivity, restricting fish migrations. Reductions in fish populations have been reported since the cascade was completed, including the extinction of the sturgeon (Acipenser oxyrinchus) and the blue bream (Ballerus ballerus). In addition, natural reproduction of Atlantic salmon (Salmo salar) does no longer exist, according to the current knowledge. It is impossible for the salmon to pass the first hydropower station Riga Hes near the Daugava river mouth, to reach the historical spawning areas upstream Plavinas Hep. Consequently, fish-stocking was implemented to maintain the fish populations. The hatchery-reared smolts are released downstream Riga Hes, but since they are not tagged it is not possible to differ between farmed and wild fish.

There are still potential spawning areas for Atlantic salmon in the tributary River Ogre, merging with Duagava between Riga Hep and Kegums Hep. The purpose of this study is to see how Atlantic salmon spawners behave when transported upstream past Riga Hep and released in the River Ogre.  In theory some of them could explore and spawn in Ogre River. Others may become ”fallbacks”. 
17 salmons were tagged subcutaneously with radio transmitters and released upstream a small private-owned hydropower station in Ogre River. The fish were monitored after release using two logger stations (one by River Ogre in a bend upstream Ogre hep, and one at Riga Hep in Daugava) and additional manual tracking.  Unfortunately heavy rains caused severe flooding in River Ogre and consequently all spill gates were opened at Ogre dam. The water was very turbid and coloured. From the automatic logger stations we could see that some tagged salmon immediately swam to Riga Hep. During manual tracking we could see that some were stuck in the intake channel of the Ogre Hep, or migrated slowly downstream, eventually reaching Daugava. Some individuals even went upstream Daugava after their visit at Riga Hep, swimming in the turbine outlets of Kegums Hep. The majority of the tagged salmon passed through the Riga Hep turbines to continue downstream.

At this moment we are preparing to tag another group of fish, which hopefully will be released under more ”normal” circumstances. Assuming that the spill gates at Ogre Hep will remain closed, the new fish will not be able to swim downstream past the Ogre Hep and instead they will have no choice but to remain in the Ogre River, and hopefully migrate upstream towards the spawning areas.

For me personally it has been a great adventure being in Latvia, and I’m learning a lot. The people are really nice and helpful in many ways. It is a nice stay!

Best Regards / Oscar Askling

The River Torne, situated on the border between Sweden and Finland, and one of Sweden’s few free flowing rivers, is experiencing modern day record returns of Atlantic salmon spawners with over 100 000 migrating fish so far this year. There are also reports of relatively good salmon runs in other rivers in the countys of Norrbotten and Västerbotten in northern Sweden. In the River Kalix and the River Byske more than 6000 upstream migrating spawners have been recorded and the River Vindel is aproaching its 13 000th upstream migrant in the fishcounter at Stornorrfors Hydropower station.

Tougher fishery regulations in the Baltic sea as well as at the river mouths, reduced effects of diseases on the salmon populations and restoration work in the salmon rivers are factors that might have contributed to the increased returns. Even with this year’s encouraging runs there are widespread hopes of continued increases in the years to come. The farsighted may also bear in mind that the “records” and “good runs” are in comparison with the severely weakened salmon populations of recent history.

Upstream migrating spawners in the River Torne, 2009-2014. Data from www.rktl.fi.