Non-native pink salmon (Oncorhynchus gorbuscha) have increased rapidly in Norwegian rivers since 2017, yet their marine ecology remains poorly understood. To assess variation in marine growth, we analysed scales from 476 individuals returning to northern (Barents Sea region) and central (Atlantic region) Norway in 2019 and 2021. Clear differences in growth and body size emerged between regions and years, with fish returning in 2019 experiencing the poorest growth and reaching the smallest adult size. Differences in growth histories indicate that pink salmon captured in the two regions may have experienced distinct marine feeding resource conditions, possibly because they followed different migratory pathways, beginning in the first weeks at sea. Approximately one-third of individuals experienced distinct periods of depressed growth during their first spring and summer at sea, and these events were more common among fish returning to central Norway. Mid- to late-season growth during the first year at sea strongly influenced adult size, highlighting the importance of favourable conditions during this period. At the same time, it was shown that growth after the winter could more than compensate for poor growth up until then. The pronounced variability in growth performance suggests that environmental conditions during the marine phase strongly shape adult size and may influence the future invasion potential of pink salmon in the North Atlantic. As this invasive species continues to expand, continued monitoring of growth and improved understanding of their marine ecology and environmental drivers of growth will be essential for anticipating invasion dynamics and impacts on native ecosystems.
Bioavailable strontium isotope ratios (87Sr/86Sr) have broad applications for geolocation and movement reconstructions in ecology, paleontology, archaeology, forensics, and environmental and food sciences. These applications require a comprehensive 87Sr/86Sr reference dataset to identify isotopically distinct areas. Bioavailable 87Sr/86Sr reference datasets have been created for many regions world-wide and are based on a large range of different sample materials including soil, water, flora, and fauna. Here we compiled and harmonized 28,347 published bioavailable 87Sr/86Sr data from over 150 countries representing decades of work by hundreds of researchers to provide a global dataset as a basis for reference and isoscape development. These data provide researchers across many different disciplines with a common reference dataset to use as a foundation for their research projects. Metadata and method details are provided to allow for the individual assessment of the data. The dataset is available at two community data repositories dedicated to stable isotope data, IsoArcH and IsoBank.
Aim Unlike humans, brown bears (Ursus arctos) uniquely preserve skeletal muscle mass and function during months of hibernation despite prolonged fasting and inactivity. We investigated how mitochondrial energetics respond in skeletal muscle to support this remarkable resilience. Methods Muscle biopsies from eight wild brown bears were collected during hibernation and again in the active summer season. We assessed mitochondrial respiration using high-resolution respirometry and evaluated changes in protein expression, enzyme activity, and mitochondrial content through proteomics, Western blotting, enzymatic assays, and DNA quantification. Results Hibernation was associated with lower mitochondrial respiratory capacity, largely due to a reduction in mitochondrial density rather than damage or dysfunction. Despite reduced SDH subunit expression in the whole skeletal muscle, SDH activity remained stable. This likely reflects post-translational regulation and increased, or at least maintained, functional efficiency of the remaining Complex II, allowing mitochondrial respiration to shift toward Complex II-mediated electron entry during hibernation. Proteomic analyses revealed targeted adjustments that maintained energy efficiency, supported both fat and carbohydrate oxidation at low temperatures, and minimized energy loss. Additionally, selective downregulation of mitochondrial dynamic proteins may help protect against muscle degradation. Conclusion These findings highlight a temperature-sensitive, multifaceted strategy that preserves mitochondrial energetics during prolonged inactivity, despite reduced mitochondrial density. The selective maintenance of electron flow and fuel flexibility offers novel insights for mitigating muscle wasting in sedentary or immobilized humans.
Mixed-species forests in southern Fennoscandia have been subject to deforestation and degradation by land-use changes and intensive forest management. Given the importance of mixed forests for biodiversity and climate change adaptation, it is crucial to conserve remaining patches and manage them in ways that sustain or restore their associated habitats for biodiversity. We evaluated whether restorative selective cutting contributes to forest diversity by fostering tree-related microhabitats (TreMs). We inventoried TreMs on 2346 trees from 42 mixed oak-dominated forests in Sweden and Norway and compared the composition and diversity of TreMs at the plot and tree scale in selective cutting stands (25 % basal area removed 7 or 21 years ago, cutting conifers preferably and opening the space around large deciduous trees) and control stands (no recent intervention). At the tree scale, higher TreM diversity was observed on trees from selective cutting plots, but only in stands cut 7 years ago. Moreover, selective cutting had a positive effect on the epiphyte group that includes bryophytes and lichens. At the plot scale, however, there was no difference in TreM diversity between treatments. At both scales, diameter at breast height was the prevalent factor that positively affected TreM diversity, together with tree species and living status: conifers had a negative effect on TreMs, whereas higher proportion of standing dead trees explained higher TreM diversity. Our results indicate that selective cutting with clear ecological-restoration goals is a favourable approach to maintaining TreMs in mixed forests of hemiboreal regions, although its long-term implications need further research.
Local fisheries risk marginalization in the blue economy. This study explores fishers' views on sustainability challenges for local fisheries in Northern-Norway through a social survey approach. We asked: "What are the three greatest challenges for fisheries in your municipality today?" and "In 30 years, what will be the greatest challenges?" Fishers' concerns were compared to recent scientific literature on fishers 'challenges globally to identify issues not emphasized by our respondents (non-issues). These are issues that may be silenced, considered non-problematic or that fishers lack knowledge of. Data from 360 fishers showed that challenges identified by the fishers broadly pertained to nine domains - competition for space and resources, access to infrastructure, workforce, economy, environment, governance, local communities, illegal activity and recognition of fisheries, fishers and fishing culture. Aquaculture, competition within fisheries, access to landing sites, and recruitment were frequently mentioned as specific challenges under these domains. Recruitment and depopulation of local communities were mentioned by a higher proportion of fishers as a future challenge than a present day one. Surprisingly, non-issues included challenges with known local relevance and high saliency, such as safety in fisheries, destructive fishing practices, climate-change adaptation, environmental toxins in seafood and gender equality. To sum up, challenges tied to the blue economy, particularly aquaculture, along with the current downward trends within fisheries when it comes to number of fishers and local fishing industry are key challenges facing local fisheries. Alternative visions for the blue economy that holds space for local fishing activity, are called for.
