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Population structure and history of North Atlantic Blue whales (Balaenoptera musculus musculus) inferred from whole genome sequence analysis
Get PDFKnowledge of genetic diversity and structure is essential for developing conservation strategies for endangered species. Blue whales were hunted to near extinction in the mid-twentieth century. Not-withstanding almost 380,000 animals killed globally, much remains unknown about their population structure and migration patterns. Herein, we use whole genome sequencing to elucidate the poorly understood population genetics of North Atlantic (NA) blue whales. We generated a de novo genome assembly for a NA blue whale to analyze 19 other whole genomic sequences and 31 complete mitochondrial genomes. Present-day and historical samples (earliest from 1876) from the Atlantic and Antarctic Oceans were included to understand the impact of whaling on the genetic diversity of this species. We found low but statistically significant population structuring and high genetic diversity. Demographic modeling using fastsimcoal2 rejected an absence of gene flow between eastern and western NA blue whales and suggested an asymmetric west to east gene flow. Introgression estimated using D-statistics between blue and fin whales (Balaenoptera physalus), was observed in all present-day samples. This gene flow was found to be unidirectional from fin whales to blue whales and accounts for ~ 3.5% of the NA blue whale’s genome. Our sequencing and population structure analyses provide a genomic baseline to inform ongoing conservation strategies for this iconic species.publishedVersio
Kartlegging av snøkrabbebestanden på norsk sokkel i Barentshavet - 2023 — Toktrapport fra tokt med F/F Kristine Bonnevie 1. juni til 17. juni 2023 (2023006011)
Get PDFToktets målsetning var å øke kunnskapen om bestanden av snøkrabbe i Barentshavet, samt utvikle metodikk for overvåkningsarbeidet og teknologi til bruk i det kommersielle fiskeriet. Toktet ble i 2023 utført i samarbeid mellom faggruppe «Bentiske ressurser og prosesser» som har ansvar for bestandsrådgivninga og faggruppe «Fangst» som driver forskning og utvikling av fangstteknologi.Kartlegging av snøkrabbebestanden på norsk sokkel i Barentshavet - 2023 — Toktrapport fra tokt med F/F Kristine Bonnevie 1. juni til 17. juni 2023 (2023006011)publishedVersio
Genomic and Transcriptomic Diversification of Flagellin Genes Provides Insight into Environmental Adaptation and Phylogeographic Characteristics in Aeromonas hydrophila
Get PDFAeromonas hydrophila is an opportunistic motile pathogen with a broad host range, infecting both terrestrial and aquatic animals. Environmental and geographical conditions exert selective pressure on both geno- and phenotypes of pathogens. Flagellin, directly exposed to external environments and containing important immunogenic epitopes, may display significant variability in response to external conditions. In this study, we conducted a comparative analysis of ~ 150 A. hydrophila genomes, leading to the identification of six subunits of the flagellin gene (fla-1 to fla-4, flaA, and flaB). Individual strains harbored different composition of flagellin subunits and copies. The composition of subunits showed distinct patterns depending on environmental sources. Strains from aquatic environments were mainly comprised of fla-1 to fla-4 subunits, while terrestrial strains predominated in groups harboring flaA and flaB subunits. Each flagellin showed varying levels of expression, with flaA and flaB demonstrating significantly higher expression compared to others. One of the chemotaxis pathways that control flagellin movement through a two-component system was significantly upregulated in flaA(+ 1)/flaB(+ 1) group, whereas flaA and flaB showed different transcriptomic expressions. The genes positively correlated with flaA expression were relevant to biofilm formation and bacterial chemotaxis, but flaB showed a negative correlation with the genes in ABC transporters and quorum sensing pathway. However, the expression patterns of fla-2 to fla-4 were identical. This suggests various types of flagellin subunits may have different biological functions. The composition and expression levels of flagellin subunits could provide valuable insights into the adaptation of A. hydrophila and the differences among strains in response to various external environments.publishedVersio
Toktrapport fra reketoktet i Skagerrak og Norskerenna 2024 — Reketoktet i Skagerrak og Norskerenna 2024
Get PDFHavforskningsinstituttet (HI) har siden 1984 gjennomført en årlig bunntrålundersøkelse for dypvannsreke (Pandalus borealis) i Skagerrak og Norskerenna, for å overvåke rekebestanden og samle inn data om utbredelse, biomasse, rekruttering og demografi. Undersøkelsen gir fiskeriuavhengige data til ICES-vurderingen av denne rekebestanden (pra.27.4a). Alle fiskearter i fangstene er registrert med total biomasse og lengdemålinger, med individuell prøvetaking (vekt, lengde, modenhetsstadium, otolitter) av atlantisk torsk, skolest, vassild, kveite, blålange, breiflabb og pigghå. Sjøkreps blir lengdemålt og kjønnsbestemt, og hunnens modenhetsstadium bestemmes. Det tas bilder av bunndyr fra hver stasjon. Toktnummer: 2024001001Toktrapport fra reketoktet i Skagerrak og Norskerenna 2024 — Reketoktet i Skagerrak og Norskerenna 2024publishedVersio
Exploring the nutrient composition of various shellfish available in Norway and their role in providing key nutrients
Get PDFShellfish constitute a diverse group of aquatic animals, encompassing numerous species of molluscs and crustaceans able to supply important nutrients beneficial to human health. However, information regarding their nutritional properties remain scarce. In this paper, we explore the nutrient composition of shellfish, including shrimps, mussels, scallops, crabs, crayfish, and lobsters, collected from supermarkets, local fishermen, and the North Atlantic Ocean. By analysing over 800 samples collected between 2011 and 2021, we show that shellfish are able to provide high quantities of protein (8.1–21 g/100 g), essential amino acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) [sum of 0.061–4.3 g/100 g], vitamin B12 (0.82–65 µg/100 g), vitamin E (0.75–28 mg/100 g), zinc (0.61–7.9 mg/100 g), iodine (3.1–2100 µg/100 g), and selenium (7.2–590 µg/100 g). The hepatopancreas of crustaceans was found to be substantially more nutrient-dense than the white meat. Furthermore, the shellfish included in this study cannot be considered good sources of riboflavin, niacin, folate, and vitamin D3. We conclude that shellfish can substantially contribute to recommended nutrient intakes by providing high quantities of key nutrients. The data presented in this paper are an important contribution to the understanding of shellfish as a source of nutrients and to existing food composition databases.publishedVersio
Exploiting the “gold of the ocean”: Can live storage solve the paradox of the purse seine fishery for Atlantic bluefin tuna in Norway?
Get PDFThe Norwegian quota for Atlantic bluefin tuna (ABT) (Thunnus thynnus) is not completely caught every year. This is paradoxical because Norway is a leading fishing nation. The fishery is currently executed by rod-and-reel and purse seine, with ∼ 80 % of the quota being allocated to the latter. Purse seine is therefore the main determinant for the overall success of the fishery and vessels aim to take catches that are manageable for their size (typical LOA < 40 m). These vessels are not designed to target ABT, so they tend to have variable capture efficiency, inadequate catch control technology and often produce inconsistent product quality of relatively low value. Furthermore, participation in more profitable fisheries with better shore-based infrastructure and marketing channels is prioritised over ABT fishing. The storage of purse seine caught ABT in cages is currently practiced worldwide but not in Norway. Storage allows on-demand supply to the market and can improve quality by allowing physiological recovery after capture. There is therefore great interest from Norwegian policymakers and industry in developing a live storage fishery. This manuscript investigates aspects related to ABT live storage in Norway. Findings are presented from sea trials exploring the feasibility of these procedures. Challenges that will determine the future perspective of Norwegian live storage are discussed, and the potential of alternatives such as longlines, traps and rod-and-reel is examined. Any future success in developing the Norwegian ABT fishery will serve as an example for other fisheries around the world facing similar challenges.publishedVersio
Carbon stocks in Norwegian eelgrass meadows across environmental gradients
Get PDFSeagrass meadows are well-known for their capacity to capture and store blue carbon in sediments. However carbon stocks vary significantly between meadows, spanning more than three orders of magnitude on both local and global scales. Understanding the drivers of seagrass carbon stocks could help improve strategies for incorporating blue carbon into management plans. Here, we measured sediment carbon stocks in eelgrass (Zostera marina) meadows and unvegetated areas along the Norwegian coast, spanning wide gradients in temperature, wave exposure, water depth, salinity, and eelgrass biomass. Carbon stocks were generally higher in eelgrass meadows than in adjacent unvegetated areas, yet they displayed considerable variation (400 − 30 000 g C m−2 at 50 cm sediment depth) even among nearby sites. Overall, the highest carbon stocks were found in deeper, muddier, sheltered meadows near river mouths. These sites likely have the highest input and retention of carbon from different sources. Consequently, they should be prioritized as conservation targets for preserving coastal blue carbon stocks. Despite ever-increasing efforts to quantify seagrass blue carbon globally, high uncertainties still persist, partly due to differing methodologies, processes, and environmental context. Blue carbon stock estimates could be improved through the coordination of standardised mapping and sampling methods.publishedVersio
The combined effects of warming, ocean acidification, and fishing on the northeast Atlantic cod (Gadus morhua) in the Barents Sea
Get PDFWith a biomass of ∼4 million tonnes, and annual catches of 900 000 tonnes, the northeast Atlantic (NEA) cod stock in the Barents Sea is the world’s largest. Scientists have been trying to explain the variability in recruitment of this stock for over 100 years, in particular connecting it to spawning stock biomass and environmental factors such as temperature. It has been suggested that the combination of ocean acidification and global warming will lead to a significant decrease in the spawning stock biomass and an eventual (end of this century) collapse of the NEA cod stock in the Barents Sea. We show that a temperature- and OA-driven decline in recruits will likely lead to a smaller cod stock, but not to a collapse. Instead, the level of fishing pressure and, not least, the choice of the recruitment function applied in simulations and how it relates to temperature, is extremely important when making such forecasts. Applying a non-linear relationship between temperature and spawning stock biomass—as has been done in studies that predict a collapse of the NEA cod stock—does not improve accuracy and, in addition, adds a large decrease in number of recruits that is not biologically supported.publishedVersio
One hundred priority questions for advancing seagrass conservation in Europe
Get PDFSocietal Impact Statement Seagrass ecosystems are of fundamental importance to our planet and wellbeing. Seagrasses are marine flowering plants, which engineer ecosystems that provide a multitude of ecosystem services, for example, blue foods and carbon sequestration. Seagrass ecosystems have largely been degraded across much of their global range. There is now increasing interest in the conservation and restoration of these systems, particularly in the context of the climate emergency and the biodiversity crisis. The collation of 100 questions from experts across Europe could, if answered, improve our ability to conserve and restore these systems by facilitating a fundamental shift in the success of such work. Summary Seagrass meadows provide numerous ecosystem services including biodiversity, coastal protection, and carbon sequestration. In Europe, seagrasses can be found in shallow sheltered waters along coastlines, in estuaries & lagoons, and around islands, but their distribution has declined. Factors such as poor water quality, coastal modification, mechanical damage, overfishing, land-sea interactions, climate change and disease have reduced the coverage of Europe’s seagrasses necessitating their recovery. Research, monitoring and conservation efforts on seagrass ecosystems in Europe are mostly uncoordinated and biased towards certain species and regions, resulting in inadequate delivery of critical information for their management. Here, we aim to identify the 100 priority questions, that if addressed would strongly advance seagrass monitoring, research and conservation in Europe. Using a Delphi method, researchers, practitioners, and policymakers with seagrass experience from across Europe and with diverse seagrass expertise participated in the process that involved the formulation of research questions, a voting process and an online workshop to identify the final list of the 100 questions. The final list of questions covers areas across nine themes: Biodiversity & Ecology; Ecosystem services; Blue carbon; Fishery support; Drivers, Threats, Resilience & Response; Monitoring & Assessment; Conservation & Restoration; Governance, Policy & Management; and Communication. Answering these questions will fill current knowledge gaps and place European seagrass onto a positive trajectory of recovery.publishedVersio
Northeast Atlantic fish stock productivity hindcasts and forecasts from a Bayesian framework reveal pronounced climate-induced dynamics
Get PDFClimate change continues to exert pressure on ocean ecosystems. The fisheries-related responses, such as altered body growth, recruitment and spatial distribution of the targeted stock(s), have generally been reasonably well investigated. Nevertheless, there are still important knowledge gaps in how biophysical drivers impact stock productivity and thereby sustainable harvest levels. Considering this, we investigated 26 fish stocks in the Northeast Atlantic, a region characterized by accelerated climate change effects and a diverse set of fisheries. A novel, stepwise, Bayesian framework to quantify stock productivity was established to identify shared trends and project future patterns, aiming at determining essential baselines for adaptive fishery management in the face of climate change. Despite variation among large marine ecosystems and stocks, an overall declining trend in productivity over the past four decades was observed, especially in high-latitude areas. These hindcast results were mainly attributed to higher temperatures posing negative effects on productivity, which was dependent on the stock's thermal preference. Contrastingly, the proxy for food availability – gross secondary production – exhibited less consistent impacts. In the forecast, the applied Shared Socio-economic Pathways (SSPs) indicated that most stocks are likely to encounter adverse effects, with the worst cases expected to occur under SSP2-4.5 in the 2050s, and under SSP5-8.5 in the 2090s. Thus, this study generally not only supports earlier climate vulnerability assessments (‘scorings’) of experts but also provides evidence for revised directional effects under climate change, underlining the complexity of processes affecting stock productivity.publishedVersio