Åsa Enefalk, Ari Huusko, Pauliina Louhi and Eva Bergman recently published the paper “Fine stream wood decreases growth of juvenile brown trout (Salmo trutta L.)” in the journal Environmental Biology of Fishes. In the abstract, the authors write:

A juvenile brown trout (Salmo trutta) hiding in fine stream wood.

“In this study, the growth rate, gut fullness, diet composition and spatial distribution of brown trout was compared between artificial channels with and without fine wood (FW). Access to FW resulted in significantly lower brown trout growth rates over the study period from late summer to early winter as water temperatures declined from 17 °C to 1 °C. Access to FW resulted in minor differences in occurrence of the most common taxa found in brown trout diets, except for chironomid larvae which were found in c. 60% of the brown trout guts from control treatments but in only 30% of the guts from FW treatments in early winter. Diet consisted primarily of case-bearing and free-living Trichoptera larvae, Asellus, chironomid and Ephemeroptera larvae. Brown trout gut fullness was not significantly affected by access to FW bundles. Brown trout aggregated among FW but were more evenly distributed in channels lacking it. Our results suggest that juvenile brown trout use FW as a shelter at a wide range of water temperatures, and that this behaviour may result in reduced growth rates during their first fall and the onset of their first winter. We also show that prey availability and the composition of brown trout diet changes from late summer to early winter and that FW has a small but significant effect on brown trout diet composition.”

Read the paper here, or contact any of the authors.

On 12 March (tomorrow) Eva Bergman, NRRV Professor, will give a seminar titled “Improvement and evaluation of connectivity and habitat quality for sustainable hydropower”. The seminar begins at 13:15 in room 5F416 at Karlstad University. Everyone is welcome to attend the seminar.

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

I en rapport, och vid ett seminarium på måndag i Arlanda, presenterar Karlstads universitet nu resultaten från ett femårigt forskningsprojekt som undersökt möjligheter till att öka överlevnaden hos nedströmsvandrande laxfisk i Klarälven. I ett pressmeddelande i anslutning till seminariet skriver universitetet tillsammans med Fortum:

“Sedan 1930-talet har lekvandrande lax och öring årligen infångats vid första vandringshindret i älven och åkt lastbil förbi den utbyggda delen för att släppas av och möjliggöra naturlig lek på platser ovanför det åttonde kraftverket, Edsforsen. Parallellt sker kompensationsutsättningar av odlad laxfisk nedströms det första vandringshindret för att möjliggöra ett fiske efter lax och öring i Vänern. Den vilda laxfisken skyddas samtidigt genom fredningsbestämmelser.

Karlstad universitet och Fortum har bedrivit forskningssamarbete om lax och öring i Klarälven under många år. Den kumulativa dödligheten hos ung lax under nedströmsvandring och kraftverkspassager har visat sig vara hög. Bland de resultat som redovisas från det senaste projektet påvisades en ännu högre dödlighet för utlekt fisk, där endast enstaka märkta utlekta laxar framgångsrikt passerade alla dammar. Projektet – som riktat in sig på att ge underlag för att förbättra just överlevnaden för laxungar och utlekt lax på vägen från lek – visar också att spill vid kraftverken har stor betydelse för den utlekta laxens passagemöjligheter. Liknande resultat inhämtades, som en del av projektet, för ung lax i Winooski River i USA.

– Kraftverken utgör de facto vandringshinder för fisken, både uppströms och nedströms. I detta forskningsprojekt har vi fokuserat på att få kunskap om laxens vandringsbeteende för att kunna förbättra möjligheterna för fiskens nedströmsvandring. Något som tidigare varit eftersatt, inte bara i Klarälven utan på många platser i världen, säger projektledaren Larry Greenberg på Karlstads universitet.

Projektet föreslår att en ökad överlevnad bland nedströmsvandrande laxfisk skulle kunna åstadkommas genom att fisken leds av från Edsforsens turbinintag och samlas upp för transport förbi kraftverken och sätts ut nedströms Forshaga kraftverk. Eftersom det finns ytterst få exempel på avledare vid kraftverk av Edsforsens storlek och geografiska placering, är samtliga studerade åtgärdsalternativ att betrakta som experimentella och kommer att kräva utvärderingar och modifieringar under en försöksperiod som bör spänna över flera år. Av de sex olika åtgärdsförslag som studerats förordas två lösningar med s k. beta-avledare. Alternativet beräknas kosta ca. 130 milj kr som engångskostnad samt ca. 8,5 milj kr i årliga löpande kostnader.

– Det är viktigt att hitta rätt lösning för rätt vattendrag. Ett exempel på detta är just Klarälven – ett vattendrag med åtta vattenkraftverk från första vandringshinder upp till laxens kvarvarande lek- och uppväxtområden – där vi under senare tid sett en positiv trend för den unika populationen av Klarälvslax. Projektets resultat har nu gett oss viktig kunskap om hur laxstammen i Klarälven ytterligare kan stärkas, säger Marco Blixt som är fiskeansvarig på Fortum.

Av de cirka 8,3 miljoner kr som satsades i projektet mellan år 2012 och 2016 kommer 1,1 miljoner kr från Karlstads universitet, 2 miljoner kr från det EU-finansierade interregprojektet ”Vänerlaxens fria gång” samt ca 5,2 miljoner kr från Fortum: hälften från interna forskningsanslag och hälften från Fortums miljöfond, som finansieras genom försäljningen av Bra miljömärkt el.”

Rapporten finns tillgänglig online här: Förbättrad nedströmspassage för vild laxfisk i Klarälven

The paper “Winter sheltering by juvenile brown trout (Salmo trutta) – effects of stream wood and an instream ectothermic predator” by Åsa Enefalk, Johan Watz, Larry Greenberg and Eva Bergman was recently published in the journal Freshwater Biology. The paper presents a study on the sheltering behavior of the juvenile trout in presence and absence of burbot and bundles of stream food. In the abstract the authors write:

1. In boreal streams, juvenile salmonids spend substantial amounts of time sheltering in the streambed and in stream wood, presumably as a means of protection against the physical environment and from terrestrial endothermic predators. Relatively little is known about sheltering by salmonids in response to instream ectothermic predators.
2. We tested the effects of burbot (Lota lota) on the winter sheltering behaviour of PIT-tagged 0+ brown trout (Salmo trutta) in daylight and darkness. Sheltering in the streambed by trout was studied in the presence and absence of fine wood bundles.
3. We found that the use of streambed and fine wood was lower in darkness than in daylight. Availability of fine wood significantly decreased sheltering in the streambed, and this effect was more pronounced in daylight than in darkness. The presence of a burbot significantly decreased sheltering in the streambed, had no effect on use of fine wood and resulted in a higher number of exposed trout.
4. Our results indicate that juvenile brown trout decrease streambed sheltering in response to a burrowing, ectothermic predator.

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

Idag disputerade Diana Garavito-Bermúdez, vid Institutionen för pedagogik och didaktik på Stockholms Universitet, med avhandlingen “Learning ecosystem complexity: A study on small-scale fishers’ ecological knowledge generation”. Avhandlingen utforskar ekologiska kunskaper bland småskaliga yrkesfiskare i Vättern och Blekinge skärgård (Östersjön). På Stockholms Universitets hemsida beskrivs avhandlingen: Avhandlingen syftar till att bidra till kunskap om och förståelse för hur småskaliga fiskare lär sig kunskaper om komplexa ekosystem i sin vardag. Avhandlingen bidrar med kunskap till fälten: informella lärprocesser, ekologisk kunskap och hållbar användning och styrning av naturresurser. Den adresserar frågor om vilken kunskap som fiskare genererar i sin vardag, hur denna kunskapsgenerering påverkas av deras arbetspraktik och av deras relation till naturen. I avhandlingen studeras småskaliga fiskare inom två ekosystem: Vättern och Blekinge skärgård utifrån såväl intervjuer som observationer med betoning på intervjuer. Avhandlingen är en sammanläggningsavhandling som består av tre artiklar och en kappa. Läs kappa här.

På disputationen var Karlstads Universitet repressenterat av professor Eva Bergman, en av forskarna i betygsnämnden. Hon rapporterar om en intressant diskussion både med Diana Garavito-Bermúdez och efteråt med handledare, opponent och betygsnämnd. Alan Reid från Monash University i Australien var opponent.

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.

Larry Greenberg and Eva Bergman, researchers at NRRV, would like to promote American Institute of Fisheries Research Biologists (AIFRB). The American Institute of Fishery Research Biologists is “an organization established to advance excellence in fishery science and to promote stewardship, sustainability and wise utilization of natural resources, through support in professional development and recognition of competent achievement of its members, as measured by the highest of professional standards.” Check out the institute’s homepage here.

Greenberg and Bergman last week also attended the 146th Annual Meeting of the American Fisheries Society in Kansas City, USA. They report on many interesting presentations and inspiring discussion. We program can be read here.

Johan Watz contributed the cover photo.

The paper “Ice cover affects the growth of a stream-dwelling fish”  by Johan Watz, Eva Bergman, John Piccolo and Larry Greenberg was published as the cover article in the May issue of the scientific journal Oecologia. The journal presents its issue and the paper:

“Winter conditions are believed to play an important role in the population dynamics of northern temperate stream fi sh, challenging the ability of fi sh to physiologically and behaviourally adapt. In this issue, Watz et al. show that brown trout (Salmo trutta) that spent the winter under ice cover grew more and used a broader range of habitats than trout in uncovered stream sections. These results indicate that the presence of surface ice may function as overhead cover against terrestrial piscivores and improve the energetic status of stream fish during winter.”

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.