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Toktrapport fra reketoktet i Skagerrak og Norskerenna 2021 - Reketoktet i Skagerrak og Norskerenna 2021
Get PDFHavforskningsinstituttet (HI) har siden 1984 gjennomført et årlig bunntråltokt med fokus på dypvannsreke (Pandalus borealis) i Skagerrak og Norskerenna, for å overvåke bestanden og samle inn data på geografisk fordeling, biomasse, mengde, størrelsesfordeling og rekruttering. I 2006 ble toktet flyttet fra mai/juni til januar/februar for å oppnå bedre estimater av 1-åringene (rekruttering) og gytebiomasse (SSB) (utrognshunner). Trålredskapet som benyttes, er en Campelen forskningstrål, som brukes på de fleste av HIs bunntråltokt, men med ekstra fløyt mellom giret og fiskelinen («Nordsjørigging») for å unngå leirhal på bløt bunn, særlig i Skagerrak. Bunntemperatur og salinitet blir målt med CTD på hver trålstasjon. Toktet har 111 faste trålstasjoner. I 2021 ble alle de 111 faste stasjonene trålt; alle trålhalene var av god kvalitet. I tillegg ble det trålt på åtte stasjoner på Fladengrunn. Rekebestanden på Fladengrunn har ikke blitt overvåket siden slutten av 1990-tallet.Toktrapport fra reketoktet i Skagerrak og Norskerenna 2021 - Reketoktet i Skagerrak og Norskerenna 2021publishedVersio
Distribution and abundance of Norwegian spring-spawning herring during the spawning season in 2024
Get PDFDuring the period 13-26th of February 2023 the spawning grounds of Norwegian spring-spawning herring from Møre (62º15 ˊ N) to Tromsøflaket (71 º N) were covered acoustically by the commercial fishing vessels MS Eros and MS Vendla. The estimated biomass was about 15 % lower, and the estimated total number was about 5 % higher this year compared to last year’s survey. The uncertainty of the estimates in 2024 was much lower than last year. The surveyed population was dominated by the 2016 year class; 50 % in numbers and 57 % in biomass. Most of the spawning stock was found west of Lofoten and Vesterålen this year, more northerly distributed than in earlier years. More young herring was observed in the north than normal on this survey which is a positive sign in terms of future recruitment to the spawning stock. The estimates of abundance by age group from the survey in 2024 are recommended to be used in this year’s ICES stock assessment of Norwegian spring-spawning herring.Distribution and abundance of Norwegian spring-spawning herring during the spawning season in 2024publishedVersio
Liver condition of 0 and 1-group cod (Gadus morhua) in the Barents Sea
Get PDFLiver condition is hypothesized to be a better condition index for juvenile cod than other somatic condition indices, since cod store most of their excess energy in their liver. It is suggested that population changes in liver condition can be used as a proxy for overwinter mortality. Here, we have collected 0- and 1-group cod from the same cohort in the Barents Sea before and at the end of the winter season. We have taken measurements for somatic- and liver-based condition indices, as well as enumerating nematode endoparasites found in each individual cod. The average wet weight of sampled cod increased by 85% (approx. 0.4% day−1) from 6.0 to 10.1 g from September to February, while the average liver wet weight decreased by 15%. The relative water content of the liver also increased significantly over the winter, resulting in a 42% reduction in average dry liver weight from 0.116 to 0.067 g over the 4–5-month period between samplings. About 30% of the 1-group cod surviving the winter had less than 20% of the liver energy content of same-sized 0-group cod. The liver condition was also 5–10% lower in cod with high nematode endoparasite load than the cod without nematode endoparasites. The significance of the loss of liver energy content is discussed in relation to the marked seasonality combined with climate change and the challenges this imposes on the survival of 0-group cod in high-latitude environments during their first winter.publishedVersio
Environmentally driven changes in Atlantic salmon oxidative status interact with physiological performance
Get PDFFarmed Atlantic salmon in sea cages experience natural seasonal changes in seawater temperature and photoperiod. Atlantic salmon have more oxidized tissues in spring and early summer, and this corresponds to the period of increasing day length, temperature, and growth rate. However, the molecular mechanisms underlying the redox metabolism of Atlantic salmon exposed to the interaction of seasonal cues remain unclear. This study aims to investigate the effect of seasonal changes in temperature and photoperiod on the redox metabolism at the molecular level of Atlantic salmon. Salmon reared in tanks were subjected to simulated natural (for farmed salmon in sea cages) photoperiod and temperature to mimic spring and summer (March to August). We found that the changing photoperiod and temperature, which were simulated to spring and summer conditions, influenced the redox metabolism of Atlantic salmon over the experimental period. We showed that increased utilization of tissue antioxidants such as vitamin C, vitamin E, and reduced glutathione in the spring was restored in August. The more reduced glutathione-based redox potentials and the low levels of malondialdehyde (MDA) in August in liver and muscle suggest lowered tissue oxidative activity at that time. We further revealed that the expression profiles of genes involved in growth hormone signaling and cell cycle regulation were correlated with oxidative stress patterns. Together, these promising results reveal the molecular mechanisms underlying the ecological implications of oxidative status. The study provides new insight into the possible role redox signaling plays in the growth regulation of fish to the seasonal shift in environmental factors.publishedVersio
Novel large-scale mapping highlights poor state of sea trout populations
Get PDF1. The state of sea trout in 1251 Norwegian watercourses was assessed based on a scoring system for human pressures, abundance data, and local knowledge. 2. Over 16,000 km of rivers and lakes were available to sea trout in these watercourses, spanning from the temperate to Arctic regions. 3. Sea trout were classified to be in a good or very good state in fewer than 25% of the watercourses and in a poor or very poor state in almost 40%. Twenty-nine watercourses had lost their sea trout populations. 4. Salmon lice from aquaculture salmon farms had by far the largest adverse effect on sea trout among the human impact factors, both in the number of watercourses (83%) and river area affected (60%), and the total effect on sea trout abundance. 5. Agriculture and hydropower production also had strong adverse impacts (35% and 19% of watercourses), but substantially lower than that caused by salmon lice. Culverts related to road crossings and other habitat alterations also had impacts on sea trout in many watercourses (27%). 6. Exploitation of sea trout has been reduced in Norway in recent years, both in the marine and freshwater fisheries. Yet, the exploitation pressure was moderate or high in almost 14% of the watercourses where the state of sea trout was poor or very poor, suggesting a high potential for overexploitation in these. 7. The state of sea trout was best in the northern sparsely populated areas. However, distribution of watercourses with sea trout in a poor or very poor state was more linked to aquaculture, agriculture, and hydropower production than human population density. 8. The developed approach for large-scale mapping of state and pressures, which is vital for prioritizing management measures, may inspire other nations in their conservation effort for this important species. acidification, anthropogenic pressures, brown trout (Salmo trutta), culverts, exploitation, hazardous substances, salmon lice (Lepeophtheirus salmonis), sewageNovel large-scale mapping highlights poor state of sea trout populationspublishedVersionpublishedVersio
Stability study and validation of a liquid chromatography tandem mass spectrometry method for the quantitative analysis of polyphenols in fish feed ingredients
Get PDFThe perception of polyphenols as a safe, healthy, and sustainable solution for replacing synthetic antioxidants has been an important factor for their rapid growing in the global food market. Therefore, it is essential to use reliable methods for their quantification in commercial products intended for animal or human consumption. The purpose of this study is to evaluate the performance of some solvents used for the extraction of selected polyphenols, explore their stability under different experimental conditions, and validate a liquid chromatography tandem mass-spectrometry method for their quantification in commercial fish feed ingredients by using the standard addition method. The regression models for gallic acid, hydroxytyrosol, catechin, oleuropein, carnosol and carnosic acid were linear in the range 0–30 μg/mL, limit of detection and quantification around 0.03 and 0.1 μg/mL, respectively, and accuracy within ± 15 % of the nominal concentrations. The method was successfully applied to the determination of specific polyphenols in commercial fish feed ingredients supplemented with polyphenols from olive and rosemary extracts.publishedVersio
One-carbon metabolism nutrients impact the interplay between DNA methylation and gene expression in liver, enhancing protein synthesis in Atlantic salmon
Get PDFSupplementation of one-carbon (1C) metabolism micronutrients, which include B-vitamins and methionine, is essential for the healthy growth and development of Atlantic salmon (Salmo salar). However, the recent shift towards non-fish meal diets in salmon aquaculture has led to the need for reassessments of recommended micronutrient levels. Despite the importance of 1C metabolism in growth performance and various cellular regulations, the molecular mechanisms affected by these dietary alterations are less understood. To investigate the molecular effect of 1C nutrients, we analysed gene expression and DNA methylation using two types of omics data: RNA sequencing (RNA-seq) and reduced-representation bisulphite sequencing (RRBS). We collected liver samples at the end of a feeding trial that lasted 220 days through the smoltification stage, where fish were fed three different levels of four key 1C nutrients: methionine, vitamin B6, B9, and B12. Our results indicate that the dosage of 1C nutrients significantly impacts genetic and epigenetic regulations in the liver of Atlantic salmon, particularly in biological pathways related to protein synthesis. The interplay between DNA methylation and gene expression in these pathways may play an important role in the mechanisms underlying growth performance affected by 1C metabolism.publishedVersio
Advice on fishing opportunities for Barents Sea capelin in 2025 — ICES subareas 1 and 2 excluding Division 2.a west of 5°W
Get PDFThe Joint Russian-Norwegian Working Group on Arctic Fisheries (JRN-AFWG) advises that when the Joint Norwegian–Russian Fisheries Commission management plan is applied, there should be zero catches of Barents Sea capelin in 2025.Advice on fishing opportunities for Barents Sea capelin in 2025 — ICES subareas 1 and 2 excluding Division 2.a west of 5°WpublishedVersio
Challenges and opportunities when moving food production and consumption toward sustainable diets in the Nordics: a scoping review for Nordic Nutrition Recommendations 2023
Get PDFThe terms ‘Nordic countries’ or ‘The Nordics’ include the five countries Denmark, Finland, Island, Norway, and Sweden. This review includes evaluation of the Nordic countries against Food and Agricultural Organisation (FAO)/World Health Organizations’ (WHO) guiding principles for healthy, sustainable diets with respect to environmental impact (principles #9 – #13) and sociocultural aspects (principles #14 – #16). A food systems perspective is taken to summarize and discuss the most important challenges and opportunities for achieving sustainable diets. Food system, food security, self-sufficiency, and resilience perspectives are applied. The information can underpin decisions when developing and implementing Food Based Dietary Guidelines (FBDG) in the Nordics. None of the Nordic countries are on track to reach the 2030 UN climate and biodiversity goals. We describe how food production, processing, and consumption contribute to these and other environmental challenges, and what kinds of dietary changes/transitions consistent with these goals are required. A major challenge is the high production and consumption of meat and too low consumption of fish, vegetables, and fruits. Meat production is a major source of emissions and, together with farmed fish, heavily dependent on imported feed ingredients, leaving a large land-use and water footprint in exporting countries while domestic land resources are not used optimally. Dietary patterns have changed drastically over the past 50 years, and in large parts of the population, meat consumption has doubled since the 1970s, rendering historic food culture less useful as a basis for present-day recommendations. The Nordics have Europe’s lowest use of antibiotics in animal and fish production and have made some progress in reducing food waste along the food chain. A major opportunity is better alignment of food production and consumption based on local or regional production potentials, in conjunction with better and more constructive integration with the global food system while integrating novel technologies to reduce emissions and resource use.publishedVersio