John Piccolo recommends the short film “Lahontan Cutthroat Trout: A prehistoric legend returns“. The film briefly discusses the restoration of cutthroat trout to Pyramid Lake and the Truckee River in Nevada, USA. This strain of cutthroat trout was assumed extinct until remnants of the population were found in streams in neighboring Pilot Peaks. This started great efforts to re-introduce the socially and culturally important fish population to the lake. Watch the film here:

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Dokumentären “Tana älv – mellan tre länder” (“Tanaelv – den beste elva” på norska) ligger just nu uppe på SVT-play. FIlmen handlar om laxen i älven och människorna runt den. Forskare, förvaltare, husbehovsfiskare och repressentanter för turistfisket kommer till tals. Älven – och dess biflöden – är hem för en mängd lokalt anpassade laxpopulationer och fisketrycket måste minskas för att skydda hotade laxpopulationer. Detta skapar både lokala och internationella konflikter.

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Se filmen på SVT-Play eller på NRK:s hemsida.

nyqvist2016cLast 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.

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Freshwater pearl mussels.

The paper “Heavy loads of parasitic freshwater pearl mussel (Margaritifera margaritifera L.) larvae impair foraging, activity and dominance performance in juvenile brown trout (Salmo trutta L.)”  by Karl Filipsson, Tina Petersson, Johan Höjesjö, John Piccolo, Joacim Näslund, Niklas Wengström, Martin Österling was recently published in Ecology of Freshwater Fish. In the abstract the authors write:

“The life cycle of the endangered freshwater pearl mussel (Margaritifera margaritifera) includes a parasitic larval phase (glochidia) on the gills of a salmonid host. Glochidia encystment has been shown to affect both swimming ability and prey capture success of brown trout (Salmo trutta), which suggests possible fitness consequences for host fish. To further investigate the relationship between glochidia encystment and behavioural parameters in brown trout, pairs (n = 14) of wild-caught trout (infested vs. uninfested) were allowed to drift feed in large stream aquaria and foraging success, activity, agonistic behaviour and fish coloration were observed. No differences were found between infested and uninfested fish except for in coloration, where infested fish were significantly darker than uninfested fish. Glochidia load per fish varied from one to several hundred glochidia, however, and high loads had significant effects on foraging, activity and behaviour. Trout with high glochidia loads captured less prey, were less active and showed more subordinate behaviour than did fish with lower loads. Heavy glochidia loads therefore may negatively influence host fitness due to reduced competitive ability. These findings have implications not only for management of mussel populations in the streams, but also for captive breeding programmes which perhaps should avoid high infestation rates. Thus, low levels of infestation on host fish which do not affect trout behaviour but maintains mussel populations may be optimal in these cases.”

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

Fiskmärkning i Dalälven

Posted by Daniel Nyqvist | Nyheter

Anna Hagelin, tjänstledig doktorand vid Karlstads Universitet, jobbar med återetablieringen av havsvandrande lax och öring i Dalälven. Som en del av detta arbete studeras hur vandrande laxfisk beter sig på ännu otillgängliga (pga av kraftverksdammar) områden av älven. Under hösten har lekvandrande öring fångats vid Älvkarleby, den nedersta kraftverksdammen i Dalälven, radiomärkts och transporterats upp till ett nyligen restaurerat lekområde i Gysinge, vid Färnebofjärdens Nationalpark. Här har sedan öringens rörelser och val av lekplatser studerats.

Länstyrelsen i Gävleborg har gjort en film om fiskmärkningen. Se den här:

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Läs mer om projektet på “Projekt LIV – laxfisk i nedre Dalälven” på Länsstyrelsens hemsida.

learning_ecosystem_complexityIdag 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.

Nors – föredrag och foton

Posted by Daniel Nyqvist | Nyheter

Norsfiskar (Osmeridae) finns över stora delar av norra halvklotet, både sötvatten och i havet. På många platser migrerar de i stora antal upp i älvarna för att leka och efter lek driftar ägg och larver nedströms, tillbaka mot sjön eller havet.

I föredraget “Biology of eulachon in the Fraser River: critical knowledge gaps” presenterar Doug Hay forskning om Eulachon (Thaleichthys pacificus), norsen på den nordamerikanska Stillahavs kusten. Han pratar bland annat om beståndsuppskattningar baserade på fångst av driftande ägg/larver och möjliga telemetriundersöknignar. Se föredraget här:

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Vår egen nors (Osmerus eperlanus) i Vänern övervakas ute i sjön medan kunskaperna om fiskens berömda lekvandringar är relativt begränsade. Läs om norsbeståndet i Vänerns Vattenvårdsförbunds årsskrift.

Vackra foton på Rainbow smelt (Osmerus mordax, en annan norsfisk) från östra Nordamerika finns här: P.E.I. smelt run caught on camera by Ph.D. student Sean Landsman.

In July, John Piccolo traveled to Bangor, Wales for the annual meeting of the Fisheries Society of the British Isles. The meeting focused on genomics and fisheries. Genomics are a new and rapidly-developing tool for understanding the ecology and conservation of organisms. John published a short article about conservation genomics of salmon in the conference proceedings: Conservation genomics: coming to a salmonid near you

He also points out that the keynote speakers at the conference, Robin Waples, Louis Bernatchez, and Craig Primmer did a great job of summarizing recent developments in fisheries genomics in the following symposium papers:

John also recommends an article of salmon conservation genomics from Devon PearseSaving the spandrels? Adaptive genomic variation in conservation and fisheries management.

Next year is the 50th anniversary of the Fisheries Society of the British Isles.The annual meeting – themed Understanding Fish Populations – will be held at the University of Exeter (UK), 3-7 July 2017.

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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.