Publications by authors named "Geir Dahle"

The genus in the North Atlantic comprises of long lived deep-waters species that have been extensively fished upon, and many stocks are severely depleted across the Atlantic. This is particularly evident for the species . In recent papers, cryptic species have been indicated within this genus and molecular markers are therefore needed to provide identification for the species, including the cryptic species as a basis for advice regarding management and rebuilding of the stocks.

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  • * Genetic analysis revealed three main groups of glacier lanternfish: one in the Mediterranean Sea, one from oceanic samples, and a third from Norwegian fjords, with the Mediterranean group showing significantly lower genetic variation.
  • * The study indicates potential local adaptations in glacier lanternfish due to ocean currents and geographical separations, suggesting that conservation and management efforts should consider these genetic divisions among populations.
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Sustainable fisheries management is important for the continued harvest of the world's marine resources, especially as they are increasingly challenged by a range of climatic and anthropogenic factors. One of the pillars of sustainable fisheries management is the accurate identification of the biological units, i.e.

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Sustainable management of transboundary fish stocks hinges on accurate delineation of population structure. Genetic analysis offers a powerful tool to identify potential subpopulations within a seemingly homogenous stock, facilitating the development of effective, coordinated management strategies across international borders. Along the West African coast, the Atlantic chub mackerel () is a commercially important and ecologically significant species, yet little is known about its genetic population structure and connectivity.

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  • The study focuses on the escape of domesticated Atlantic cod from a fish farm in northern Norway and its implications for evolutionary and conservation biology.
  • Genetic analysis confirmed that a significant portion of the sampled cod eggs had farmed ancestry, indicating that these domesticated fish are mixing with the wild population.
  • Findings highlight concerns about reduced genetic variation among farmed cod and the potential impacts of domesticated fish on local wild populations, as well as suggesting that within-cage spawning is a major source of escaped eggs.
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Lumpfish (Cyclopterus lumpus) is a transatlantic marine fish displaying large population sizes and a high potential for dispersal and gene-flow. These features are expected to result in weak population structure. Here, we investigated population genetic structure of lumpfish throughout its natural distribution in the North Atlantic using two approaches: I) 4,393 genome wide SNPs and 95 individuals from 10 locations, and II) 139 discriminatory SNPs and 1,669 individuals from 40 locations.

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Identifying how physical and biotic factors shape genetic connectivity among populations in time and space is essential to our understanding of the evolutionary trajectory as well as the management of marine species. Atlantic cod is a widespread and commercially important marine species displaying several ecotypes with different life history strategies. Using three sets of SNPs: neutral, informative, and genome-inversion linked, we studied population genetic structure of ~2500 coastal Atlantic cod (CC) from 40 locations along Norway's 2500 km coastline, including nine fjords.

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Introduction: Left ventricular distension is a major concern with postcardiotomy veno-arterial extracorporeal membrane oxygenation (VA-ECMO) supporting a critical heart failure after cardiac surgery. This porcine study evaluates the effects of left ventricular venting on cardiac function during ECMO-supported circulation and after weaning from ECMO.

Methods: Twenty anaesthetised open-chest pigs were put on cardiopulmonary bypass with aortic cross-clamping and suboptimal cardioplegic arrest for 40 min.

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Background: In species showing partial migration, as is the case for many salmonid fishes, it is important to assess how anthropogenic pressure experienced by migrating individuals affects the total population. We focused on brown trout (Salmo trutta) from the Guddal River in the Norwegian Hardanger Fjord system, which encompasses both resident and anadromous individuals. Aquaculture has led to increased anthropogenic pressure on brown trout during the marine phase in this region.

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  • Translocation of non-native wrasses for parasite control in salmon farms poses risks to local ecosystems, as they can escape and breed with local fish.
  • A study in Norway revealed that up to 20% of the local corkwing wrasse population consists of escapees and hybrids, affecting genetic diversity in the region.
  • Despite high rates of salmon farming, the occurrence of hybrids was notably lower in other areas, indicating a need for better monitoring and management of fish translocations to ensure ecological sustainability.
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Habitat changes represent one of the five most pervasive threats to biodiversity. However, anthropogenic activities also have the capacity to create novel niche spaces to which species respond differently. In 1880, one such habitat alterations occurred in Landvikvannet, a freshwater lake on the Norwegian coast of Skagerrak, which became brackish after being artificially connected to the sea.

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Challenging long-held perceptions of fish management units can help to protect vulnerable stocks. When a fishery consisting of multiple genetic stocks is managed as a single unit, overexploitation and depletion of minor genetic units can occur. Atlantic cod () is an economically and ecologically important marine species across the North Atlantic.

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Atlantic herring is widespread in North Atlantic and adjacent waters and is one of the most abundant vertebrates on earth. This species is well suited to explore genetic adaptation due to minute genetic differentiation at selectively neutral loci. Here, we report hundreds of loci underlying ecological adaptation to different geographic areas and spawning conditions.

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Genetic markers are widely used in fisheries management around the world. While the genetic structure and markers selected are usually based on samples from the wild, very few controlled experiments have been carried out to investigate possible differences in influence on traits between markers. Here we examine the bi-allelic gene pantophysin (Pan I), widely used in the management of Atlantic cod, in a series of crosses under a range of temperatures.

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Objective: If bilateral thyroid surgery is planned and staged thyroidectomy considered in case of loss of neuromonitoring signal (LOS), a waiting time of 20 minutes is suggested for evaluation of early nerve recovery. This recommendation is based on clinical observations and has not been thoroughly validated experimentally.

Methods: Sixteen pigs were randomly studied, and electromyogram (EMG) was continuously recorded during traction injury until an amplitude decrease of 70% from baseline (BL) (16 nerves) or LOS (16 nerves), and further during 40-minute recovery time.

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Background: Marine fish populations are often characterized by high levels of gene flow and correspondingly low genetic divergence. This presents a challenge to define management units. Goldsinny wrasse (Ctenolabrus rupestris) is a heavily exploited species due to its importance as a cleaner-fish in commercial salmonid aquaculture.

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Sustainable fisheries management requires detailed knowledge of population genetic structure. The European sprat is an important commercial fish distributed from Morocco to the Arctic circle, Baltic, Mediterranean, and Black seas. Prior to 2018, annual catch advice on sprat from the International Council for the Exploration of the Sea (ICES) was based on five putative stocks: (a) North Sea, (b) Kattegat-Skagerrak and Norwegian fjords, (c) Baltic Sea, (d) West of Scotland-southern Celtic Seas, and (e) English Channel.

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  • Long-distance translocation of cleaner fish, like ballan wrasse, for controlling lice on salmon farms could harm wild populations through overexploitation and mixing distinct genetic groups.
  • A study of 18 locations across Norway, Sweden, and Spain identified two main genetic groups of ballan wrasse in Scandinavia, separated by geographic barriers, while Galician wrasse showed a significant genetic difference but partial similarity to Scandinavia.
  • The findings suggest that current practices of translocating these fish may threaten genetic diversity and sustainability in cleaner fish populations.
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Background: Quantitative traits are typically considered to be under additive genetic control. Although there are indications that non-additive factors have the potential to contribute to trait variation, experimental demonstration remains scarce. Here, we investigated the genetic basis of growth in Atlantic salmon by exploiting the high level of genetic diversity and trait expression among domesticated, hybrid and wild populations.

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Objective: Gradual impairment of nerve conduction is expected to be tightly associated with simultaneous gradual loss of vocal cord contractility, related to the fact that injured axons are connected to a defined number of muscle cells. In clinical studies, there is a time gap between observed adverse electromyographic (EMG) changes and examination of vocal cord function. This study evaluates the impact of intraoperative EMG changes on synchronous vocal cord contractility by simultaneous use of continuous intraoperative neuromonitoring (C-IONM) and accelerometry for registration of actual vocal cord function at a given change of EMG amplitude.

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The shift toward using a transfusion strategy in a ratio to mimic whole blood (WB) functionality has revitalized WB as a viable option to replace severe blood loss in civilian health care. A military-civilian collaboration has contributed to the reintroduction of WB at Haukeland University Hospital in Bergen, Norway. WB has logistical and hemostatic advantages in both the pre- and in-hospital settings where the goal is a perfectly timed balanced transfusion strategy.

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Introduction: This experimental study compares myocardial function after prolonged arrest by St. Thomas' Hospital polarizing cardioplegic solution (esmolol, adenosine, Mg) with depolarizing (hyperkalaemic) St. Thomas' Hospital No 2, both administered as cold oxygenated blood cardioplegia.

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Background: Atlantic cod (Gadus morhua L.) has formed the basis of many economically significant fisheries in the North Atlantic, and is one of the best studied marine fishes, but a legacy of overexploitation has depleted populations and collapsed fisheries in several regions. Previous studies have identified considerable population genetic structure for Atlantic cod.

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Background: In the marine environment, where there are few absolute physical barriers, contemporary contact between previously isolated species can occur across great distances, and in some cases, may be inter-oceanic. An example of this can be seen in the minke whale species complex. Antarctic minke whales are genetically and morphologically distinct from the common minke found in the north Atlantic and Pacific oceans, and the two species are estimated to have been isolated from each other for 5 million years or more.

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