The quest for successful Atlantic salmon restoration: perspectives, priorities, and maxims

Atlantic salmon is often a focal species of restoration efforts throughout the north Atlantic and it is therefore an excellent case study for how best to design programmes to address and mitigate threats and correct population declines. This perspective is written to promote the work that has been accomplished towards restoration of Atlantic salmon populations and synthesize how we believe the lessons can be used effectively to support efforts by management agencies to restore populations. We reviewed where restoration is needed for Atlantic salmon, agreed on definitions for three levels of successful restoration, and then applied these criteria to 49 published papers focused on Atlantic salmon restoration. We identified 16 successful examples of restoration among 49 papers reviewed and discussed what interventions led to success versus failure. We then addressed key questions about when hatchery stocking should be used as part of a restoration measure and whether local restoration efforts are enough when these wide-ranging species encounter broad-scale changes in the north Atlantic, specifically related to issues of climate change and to marine survival. We advise to avoid restoration as much as possible by protecting and managing existing populations and when restoration is necessary, problems should be identified and addressed in partnership with river users. With appropriate resources and research to resolve ongoing mysteries, restoration of lost Atlantic salmon populations is absolutely feasible

Swimming with the fishes: validating drift diving to identify farmed Atlantic salmon escapees in the wild

Escaped farmed Atlantic salmon Salmo salar interbreeding with wild conspecifics represents a threat to the genetic integrity and viability of wild populations. Therefore, it is necessary to accurately quantify escapees in riverine systems to monitor and mitigate interactions with wild conspecifics. Drift diving surveys are presently used in Norway to quantify the number of wild and escaped farmed salmon in rivers. However, limited information is available on the validity of the method for distinguishing escapees from wild conspecifics. Comparing the proportion of escapees calculated from drift diving (mean = 8.5%) and net captures (mean = 8.6%), we found that drift diving was well correlated with net captures (adj. r2 = 0.79). Furthermore, scale analysis from an independent data set demonstrated a 98% true positive rate when identifying and capturing farmed escapees during drift diving. The results of this study indicate that drift diving is an accurate and robust method for quantifying escaped farmed salmon, at least in rivers where observation conditions are adequate for snorkeling. In general, drift diving can be a valuable tool for stakeholders to quickly assess broad spatial extents with limited time and resources

Characterization of Emerging European-Like Porcine Reproductive and Respiratory Syndrome Virus Isolates in the United States

European-like field isolates of porcine reproductive and respiratory syndrome virus (PRRSV) have recently emerged in North America. The full-length genomic sequence of an index isolate characterized in 1999, strain EuroPRRSV, served as the reference strain for further studies of the evolution and epidemiology of European-like isolates (type 1) in the United States. Strain EuroPRRSV shared 90.1 to 100% amino acid identity with the prototype European strain, Lelystad, within the structural and nonstructural open reading frames (ORFs) and 95.3% overall nucleotide identity. The 5′ untranslated region and two nonstructural regions within ORF 1 were closely examined due to significant divergence from strain Lelystad. A 51-bp deletion in a region within ORF 1a, coding for nonstructural protein 2 (NSP2), was observed. Sequence analysis of the structural ORFs 2 to 7 of additional European-like isolates indicated that these isolates share 93% nucleotide identity with one another and 95 to 96% identity with the Lelystad strain but only 70% identity with the North American reference strain VR-2332. Phylogenetic analysis with published PRRSV ORF 3, 5, and 7 nucleotide sequences indicated that these newly emerging isolates form a clade with the Lelystad and United Kingdom PRRSV isolates. Detailed analysis of four of these isolates with a panel of 60 monoclonal antibodies directed against the structural proteins confirmed a recognition pattern that was more consistent with strain Lelystad than with other North American isolates

Bleka i Byglandsfjorden 2018 - 2021 - Status, trusler og anbefalte tiltak

Bleka i Byglandsfjorden gjennomfører hele livssyklusen i ferskvann og er sammen med Namsblanken Norges eneste gjenlevende relikte laksestamme. De kombinerte effektene av forsuring og vassdragsregulering førte bestanden til randen av utryddelse på slutten av 1960-tallet. I de femti årene som har gått siden sammenbruddet har miljøforvaltningen sammen med vassdragsregulanten og Bygland kommune iverksatt en rekke tiltak for å sikre bleka. Disse tiltakene har sammen med avtagende forsuring, gjort at bleka er på vei til å reetableres som en naturlig bestand. Blekeprosjektet ble startet opp i 1999 og har gjennomført undersøkelser og tiltak for å sikre en selvreproduserende, og på sikt, også en høstbar blekebestand. Her rapporteres status for bleka våren 2021. Rapporten er basert på resultater fra undersøkelser av fisk, bunndyr, dyreplankton og vannkjemi med hovedvekt på årene 2018 til 2020. Undersøkelsen er utarbeidet i samarbeid med: Øyvind Kaste, Liv Bente Skancke, Rolf Høgberget, Erik Höglund, Lifen Zhou Loland, Anders Hobæk, Sondre Kvalsvik Stenberg, Einar Kleiven fra NIVA, Sten Karlsson fra NINA, Arne Vethe fra Fiskebiologen i Bygland, Nils B. Kile og Bernt Olaf Martinsen fra Syrtveit Fiskeanlegg, og Jon Løyland, Ola Gullsmedmoen og Hasso Hannås, som er lokale fiskere.publishedVersio