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Validity of winter sampling for estimation of salmonid abundance by electrofishing
Full text linkElectrofishing removal sampling is a common method for abundance estimation of juvenile salmonids in streams and is usually performed during autumn. European guidelines specify that sampling should be conducted at water temperatures ≥ 5 °C, but studies investigating the validity of sampling below this threshold are lacking. We conducted electrofishing experiments during autumn and winter in three Norwegian rivers, comparing abundance estimation accuracy, rate of fish emigration from electrofishing sites, and mortality for juvenile Atlantic salmon Salmo salar and brown trout Salmo trutta. Abundance estimates were significantly more accurate during autumn than during winter, less accurate for age-0 fish than for older parr, and more accurate when the number of electrofishing passes was increased. By digging through the substrate after electrofishing, we found that a higher proportion of fish were uncatchable during winter than during autumn, and that age-0 fish were more likely than older fish to be uncatchable. For salmon older than age-0, both autumn and winter sampling consistently yielded relatively accurate abundance estimates. However, the rate of fish emigration from electrofishing sites was significantly higher during autumn than during winter and if block nets are not used, emigration during autumn sampling could cause severe underestimation of Atlantic salmon abundance. Fish mortality did not differ between autumn and winter sampling and was low for both species and all age groups. We recommend the use of block nets and conducting five electrofishing passes to reduce the likelihood of severe estimation error.publishedVersio
Rejection sampling and agent-based models for data limited fisheries
Full text linkMany of the world’s fisheries are “data-limited” where the information does not allow precise determination of fish stock status and limits the development of appropriate management responses. Two approaches are proposed for use in data-limited stock management strategy evaluations to guide the evaluations and to understand the sources of uncertainty: rejection sampling methods and the incorporation of more complex socio-economic dynamics into management evaluations using agent-based models. In rejection sampling (or rejection filtering) a model is simulated many times with a wide range of priors on parameters and outcomes are compared multiple filtering criteria. Those simulations that pass all the filters form an ensemble of feasible models. The ensemble can be used to look for robust management strategies, robust to both model uncertainties. Agent-based models of fishery economics can be implemented within the rejection framework, integrating the biological and economic understanding of the fishery. A simple artificial example of a difference equation bio-economic model is given to demonstrate the approach. Then rejection sampling is applied to an agent-based model for the hairtail (Trichiurus japonicas) fishery, where an operating model is constructed with rejection/agent-based methods and compared to known data and analyses of the fishery. The usefulness of information and rejection filters are illuminated and efficacy examined. The methods can be helpful for strategic guidance where multiple states of nature are possible as a part of management strategy evaluation.publishedVersio
Revealing trends in extreme heatwave intensity: Applying the UNSEEN approach to Nordic countries
Full text linkThe increase in heatwave intensity, causing heat stress and crop failures in many regions is a concerning impact of global climate change. In northern Europe, significant interannual variability previously prevented robust assessments of trends in heat extremes. However, with a large-ensemble seasonal hindcasts and archived forecasts dataset covering 1981–2022 multiple realisations of weather patterns can be pooled and assessed. What are recent trends of extreme temperatures? Has the risk for a 100-year heatwave event increased in Northern Europe? We apply the UNSEEN (UNprecedented Simulated Extremes using ENsembles) approach to assess the credibility of the model ensemble and use non-stationary extreme value analysis to quantify recent trends in extreme 3-day heatwaves in late spring and early summer (May to July). We find significant non-stationarity and positive trends in annual maximum heatwave intensity. We also show that heatwave volatility, i.e. the risk of clearly outstanding heatwaves, is highest in central Scandinavia.Revealing trends in extreme heatwave intensity: Applying the UNSEEN approach to Nordic countriespublishedVersio
Influencer responsibility in practice: The role of Instagram debates for individualised politics during the COVID-19 pandemic
Full text linkDuring the COVID-19 pandemic, many governments discouraged citizens from travelling both within and outside the nation in an effort to mitigate the spread of the virus. Still, some Scandinavian influencers, whose livelihood often depends on producing aesthetic travel content, chose to go abroad, which led to criticism from both followers and others. While ethical debates over air travel have taken place in social media for a long time, the specific conditions of the COVID-19 pandemic travel restrictions, combined with the centrality of travel within influencer culture, created new controversies and discussions on several influencers’ Instagram accounts in Norway and Sweden. In this article, we use digital ethnography and multimodal discourse analysis to examine discursive negotiations of different moral positions in regards to long-haul travel, the political role and responsibility of influencers, as well as how appeals to solidarity and individualised responsibility were performed and contested in socially mediated spaces during the COVID-19 pandemic.acceptedVersio
Utbedring av Rv. 9 Frøysnes langs Åraksfjorden - mulige påvirkninger på gyte- og oppvekstområder for bleke.
Full text linkOppgraderingen av Rv.9 ved Frøysnes i Åraksfjorden vil føre til at veifyllingen på ca. 1,6 km av strekningen vil legges ut i den vanndekte delen av strandsonen. Åraksfjorden er en del av leveområdet til den sjeldne og verneverdige laksen bleke. Veibyggingen forventes å ha negative effekter for fisken lokalt på den berørte strekningen, men forventes ikke å ha store effekter på overordnet bestandsnivå for bleke eller aure i Åraksfjorden. Dette begrunnes med at undersøkelsene viser at 1) negative effekter på oppvekst- og gyteforhold delvis kan motvirkes gjennom tiltak, 2) undersøkelsene viser at det med stor sannsynlighet ikke forekommer viktige gyteplasser på strekningen, og 3) den berørte strekningen utgjør en relativt sett begrenset andel av det totale tilgjengelige gyte- og oppveksthabitatet for bestandene av bleke og aure i Åraksfjorden, da den utgjør ca. 1,6 km, dvs. ca. 12 % av den ca. 13 km lange strandsonen på vestsiden av Åraksfjorden. Negative effekter av veibyggingen vil bli motvirket ved tiltak for å opprettholde en mest mulig naturtypisk overgang mot vanndekt areal. I praksis gjøres dette ved at blokk, stein og grus brukes for å skape en naturlig overgang mot vanndekt strandsone. I tillegg gjøres det tiltak for å lage gyteplasser ved å legge ut en gytegrus med en kornfordeling kjent fra eksisterende gyteplasser for bleke.Utbedring av Rv. 9 Frøysnes langs Åraksfjorden - mulige påvirkninger på gyte- og oppvekstområder for bleke.publishedVersio
Gjenåpning og habitattiltak i Grøttekilen i Lærdalselva.
Full text linkBasert på miljødesignprosjektet i Lærdalselva og et møte i desember 2019, ble NORCE LFI bedt om å foreslå aktuelle tiltak for Østfold Energi (ØE). Tiltaksplanen fra januar 2020 identifiserte flaskehalser i elva og foreslo åpning av flere kiler som tiltak for å øke fiskeproduksjonen. Foreslåtte tiltak i hovedløpet med justering av terskler, ripping av elvebunnen og utlegg av skjulstein for ungfisk ble avventet etter ønske fra Lærdal Elveeigarlag. Det ble derfor fokusert på revitalisering av kiler, med 14 kartlagte kiler der 5 kiler allerede er åpnet. Foreliggende rapport omhandler restaureringen av Grøttekilen.Gjenåpning og habitattiltak i Grøttekilen i Lærdalselva.publishedVersio
Avbøtende tiltak for effektkjøring i Daleelva – Forslag til tiltak
Full text linkI den regulerte Daleelva foregår kraftproduksjon delvis gjennom effektkjøring. Stranding av laks og aure er påvist for rogn, ungfisk og voksen fisk. Det er gjennomført avbøtende tiltak som trolig har redusert negative effekter på fisken, inkludert frivillig slipp av minstevannføring i restfelt, habitatforbedrende tiltak, tilkobling av sideløp og lokal tilpasning av elvebunnen. Ved å utvide slike tiltak til resten av elva, forventes det at negative effekter på fisken ytterligere kan reduseres. Denne rapporten oppsummerer anbefalte avbøtende tiltak for effektkjøring fra Dale kraftverksutløpet til elvemunningen i sjøen (3 km). Tiltakene ble utviklet gjennom en iterativ prosess basert på biologisk, elvemorfologisk og hydraulisk kompetanse. Utformingsforslagene ble testet i hydrauliske modeller og forbedret med mål om å minimere strandingsområder, samtidig som habitatkvaliteten ble sikret eller forbedret. Basert på dette arbeidet ble det utarbeidet forslag til en tiltaksplan. Tiltakene består av 1) tilpasning av elvebunnen ved heving og senkning, 2) etablering av varierte stryk og brekk med steinblokker, 3) sikring av vann i sideløp, samt gjentilkobling og restaurering av sideløp, og 4) habitatforbedrende tiltak som grusutlegging, ripping og reetablering av kantvegetasjon.Avbøtende tiltak for effektkjøring i Daleelva – Forslag til tiltakpublishedVersio
Vikja – Fiskebiologiske undersøkelser i perioden 2002–2023
Full text linkNORCE LFI har gjennomført fiskebiologiske undersøkelser i Vikja siden 2002 på oppdrag fra Statkraft Energi AS. I de siste årene har undersøkelsene hatt som hensikt å følge opp tidligere studier og vurdere behovet for fysiske tiltak for å bedre fiskeproduksjonen. Rapporten oppsummerer resultater og anbefalte tiltak fra 2002 til 2023.publishedVersio
Variation in general practitioners' follow-up of depressed patients starting antidepressant medication: a register-based cohort study
Full text linkBackground Guidelines recommend follow-up within 2 weeks for patients starting medication for depression. Knowledge is lacking about how general practitioners’ (GPs) follow-up varies with patients’ sociodemographic characteristics. Objective To describe follow-up by GP and specialist in mental healthcare provided to men and women with depression within 3 months of starting drug therapy. Furthermore, to examine whether follow-up varied according to patients’ age and education. Methods Registry-based cohort study comprising all patients aged ≥18 years in Norway with a new depression episode in 2014 who started on antidepressants within 12 months from diagnosis. Patients’ age and educational level were the exposures. Outcomes were follow-up by GP and/or mental healthcare specialist, and talking therapy with GP, within 90 days of first prescription. Cox proportional hazard models were used to estimate the likelihood of having follow-up contacts. Log binomial regression analysis was performed to explore the likelihood of having talking therapy with a GP. Time to first contact was illustrated by Kaplan–Meier survival curves. Results The study population comprised 17 000 patients, mean age 45.7 years, 60.6% women. Only 27.8% of the patients were followed up by GP and/or specialist within 2 weeks of the first drug dispensing, 67.1% within 90 days. Older or less educated men and women received less and later contacts than the younger or more highly educated. Conclusions Differences in age and educational level were associated with follow-up of depressed patients who started medication. This may indicate unwarranted variation in depression care that GPs should consider when prescribing antidepressants.publishedVersio
Exploring Transition in Coal- and Carbon-Intensive Regions Through an Interdisciplinary Lens
Full text linkThis chapter introduces an interdisciplinary perspective to investigate the transition process and to identify empirical evidence of social-ecological tipping points (SETPs) in the case studies on coal and carbon intensive regions (CCIRs) analyzed in the project TIPPING+. The interdisciplinary lens considers different modes of thought, frameworks, and multiple perspectives and interests from diverse stakeholders, a systems’ understanding, and different culture considerations across the CCIRs. Within this interdisciplinary process, we applied various lenses to study the potential for SETPs by combining insights from human geography, social psychology, regional socio-technical systems, and political economy perspectives on the phases of low carbon transitions and on the justice component of the transitions. Subsequently, this chapter gives an overview of how the eight CCIRs case studies in this book have applied various interdisciplinary lenses to investigate the regional transition and the emergence of SETPs.Exploring Transition in Coal- and Carbon-Intensive Regions Through an Interdisciplinary LenspublishedVersio