Blar i Published externally på forfatter "Espeland, Sigurd Heiberg"
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Are low but statistically significant levels of genetic differentiation in marine fishes ‘biologically meaningful’? A case study of coastal Atlantic cod
Knutsen, Halvor; Olsen, Esben Moland; Jorde, Per Erik; Espeland, Sigurd Heiberg; André, Carl (Journal article; Peer reviewed, 2010-12-29)A key question in many genetic studies on marine organisms is how to interpret a low but statistically significant level of genetic differentiation. Do such observations reflect a real phenomenon, or are they caused by ... -
Can we rely on selected genetic markers for population identification? Evidence from coastal Atlantic cod
Jorde, Per Erik; Synnes, Ann-Elin; Espeland, Sigurd Heiberg; Sodeland, Marte; Knutsen, Halvor (Journal article; Peer reviewed, 2018)The use of genetic markers under putative selection in population studies carries the potential for erroneous identification of populations and misassignment of individuals to population of origin. Selected markers are ... -
Combining population genomics with demographic analyses highlights habitat patchiness and larval dispersal as determinants of connectivity in coastal fish species
Knutsen, Halvor; de Oliveira Catarino, Diana Sofia; Rogers, Lauren; Sodeland, Marte; Mattingsdal, Morten; jahnke, marlene; Hutchings, Jeffrey; Mellerud, Ida Kristin; Espeland, Sigurd Heiberg; Johanneson, Kerstin; Roth, Olivia; Hansen, Michael Møller; Jentoft, Sissel; Andre, Carl; Jorde, Per Erik (Peer reviewed; Journal article, 2022)Gene flow shapes spatial genetic structure and the potential for local adaptation. Among marine animals with nonmigratory adults, the presence or absence of a pelagic larval stage is thought to be a key determinant in ... -
Combining population genomics with demographic analyses highlights habitat patchiness and larval dispersal as determinants of connectivity in coastal fish species
Knutsen, Halvor; de Oliveira Catarino, Diana Sofia; Rogers, Lauren; Sodeland, Marte; Mattingsdal, Morten; jahnke, marlene; Hutchings, Jeffrey; Mellerud, Ida Kristin; Espeland, Sigurd Heiberg; Johanneson, Kerstin; Roth, Olivia; Hansen, Michael Møller; Jentoft, Sissel; Andre, Carl; Jorde, Per Erik (Peer reviewed; Journal article, 2022)Gene flow shapes spatial genetic structure and the potential for local adaptation. Among marine animals with nonmigratory adults, the presence or absence of a pelagic larval stage is thought to be a key determinant in ... -
Diel vertical migration patterns in juvenile cod from the Skagerrak coast
Espeland, Sigurd Heiberg; Thoresen, Adine Guldborg; Olsen, Esben Moland; Stige, Leif Christian; Knutsen, Halvor; Gjøsæter, Jakob; Stenseth, Nils Christian (Journal article; Peer reviewed, 2010-04-29)We demonstrated a clear year-round diel vertical migration pattern (DVM) of small (26 to 45 cm) Skagerrak coastal cod Gadus morhua on a small geographic scale. Generalized additive models (GAMs) were used to make inferences ... -
Egg distribution, bottom topography and small-scale cod population structure in a coastal marine system
Knutsen, Halvor; Olsen, Esben Moland; Ciannelli, Lorenzo; Espeland, Sigurd Heiberg; Knutsen, Jan Atle; Simonsen, Jan Henrik; Skreslet, Stig; Stenseth, Nils Christian (Journal article; Peer reviewed, 2007-03-12)Coastal marine species with pelagic egg and larval stages, such as the Atlantic cod Gadus morhua, can be structured into genetically distinct local populations on a surprisingly small geographic scale considering their ... -
Estimating cod egg developmental stage based on DNA concentration
Espeland, Sigurd Heiberg; Sannæs, Hanne (Journal article; Peer reviewed, 2017)Pelagic egg surveys are commonly used to map Atlantic cod spawning areas in the northeastern Atlantic. However, a sampling location may not necessarily indicate a spawning location, because more developed eggs may have ... -
Fishing pressure impacts the abundance gradient of European lobsters across the borders of a newly established marine protected area
Kleiven, Portia Joy Nillos; Espeland, Sigurd Heiberg; Olsen, Esben Moland; Abesamis, Rene A.; Moland, Even; Kleiven, Alf Ring (Journal article; Peer reviewed, 2019)Marine protected areas (MPAs) are considered viable fisheries management tools due to their potential benefits of adult spillover and recruitment subsidy to nearby fisheries. However, before–after control–impact studies ... -
Harvest pressure on coastal atlantic cod (Gadus morhua) from recreational fishing relative to commercial fishing assessed from tag-recovery data
Kleiven, Alf Ring; Chacon, Albert Fernandez; Nordahl, Jan-Harald; Moland, Even; Espeland, Sigurd Heiberg; Knutsen, Halvor; Olsen, Esben Moland (Journal article; Peer reviewed, 2016-03-09)Marine recreational fishing is a popular outdoor activity. However, knowledge about the magnitude of recreational catches relative to commercial catches in coastal fisheries is generally sparse. Coastal Atlantic cod (Gadus ... -
Interbreeding between local and translocated populations of a cleaner fish in an experimental mesocosm predicts risk of disrupted local adaptation
Blanco Gonzalez, Enrique; Espeland, Sigurd Heiberg; Jentoft, Sissel; Hansen, Michael Møller; Robalo, Joana I.; Stenseth, Nils Christian; Jorde, Per Erik (Journal article; Peer reviewed, 2019)Translocation of organisms within or outside its native range carries the risk of modifying the community of the recipient ecosystems and induces gene flow between locally adapted populations or closely related species. ... -
Life history of fjord cod from the Skagerrak in the mid-2000s compared to 1905
Lund, Marthe Bråthen; Olsen, Esben Moland; Espeland, Sigurd Heiberg; Stenseth, Nils Christian (Journal article; Peer reviewed, 2011-03-01)Life history changes serve as stress indicators in harvested populations. Data from recent decades show that many species of marine fish are now maturing at younger ages and smaller sizes, associated with a general increase ... -
Lobster reserves as a management tool in coastal waters: Two decades of experience in Norway
Knutsen, Jan Atle; Kleiven, Alf Ring; Olsen, Esben Moland; Knutsen, Halvor; Espeland, Sigurd Heiberg; Sørdalen, Tonje Knutsen; Thorbjørnsen, Susanna Huneide; Hutchings, Jeffrey; Chacon, Albert Fernandez; Huserbråten, Mats Brockstedt Olsen; Villegas-Ríos, David; Halvorsen, Kim Aleksander Tallaksen; Kleiven, Portia Joy Nillos; Langeland, Thomas Kiland; Moland, Even (Peer reviewed; Journal article, 2022)The positive effects of reduced fishing pressure in marine protected areas (MPAs) are now well documented globally. Yet, evidence of MPA benefits from long-term replicated before-after control-impact (BACI) studies and ... -
Marine naturverdier i Telemark – status, trusler og muligheter. Innspill til kystsoneplan for Telemark.
Rinde, Eli; Olsen, Marianne; Steen, Henning; Dahl, Einar; Espeland, Sigurd Heiberg; Albretsen, Jon (NIVA-rapport, Research report, 2018)Denne rapporten er skrevet på oppdrag for Telemark fylkeskommune. Rapporten gir en kunnskapsstatus over forekomst og utbredelse av marine naturverdier, deres tilstand og hvilke kjente trusler disse er utsatt for med hensyn ... -
Marine protected areas increase survival of Atlantic cod
Moland, Even; Chacon, Albert Fernandez; Olsen, Esben Moland; Espeland, Sigurd Heiberg (Journal article, 2015) -
Modelling drift of pelagic offspring: the importance of egg surveys in providing a realistic model initialization.
Espeland, Sigurd Heiberg; Albretsen, Jon; Olsen, Esben Moland; Bodvin, Torjan (Journal article; Peer reviewed, 2015-07-11)Having valid information about the location and dynamics of biological processes is important for coastal management. In this context modelling, the pelagic drift of early life stages has been shown to be an important tool ... -
New perspectives on fish movement: kernel and GAM smoothers applied to a century of tagging data on coastal Atlantic cod
Espeland, Sigurd Heiberg; Olsen, Esben Moland; Knutsen, Halvor; Gjøsæter, Jakob; Danielssen, Didrik S.; Stenseth, Nils Christian (Journal article; Peer reviewed, 2008-12-09)Tagging–recovery studies have been used successfully on many occasions, and the data analysed in a variety of ways with respect to fish movement. Here we provide a synoptic account of useful statistical techniques for ... -
Restoration of Abundance and Dynamics of Coastal Fish and Lobster Within Northern Marine Protected Areas Across Two Decades
Moland, Even; Fernández-Chacón, Albert; Sørdalen, Tonje Knutsen; Villegas-Rios, David; Thorbjørnsen, Susanna Huneide; Halvorsen, Kim Aleksander Tallaksen; Huserbråten, Mats Brockstedt Olsen; Olsen, Esben Moland; Kleiven, Portia Joy Nillos; Kleiven, Alf Ring; Knutsen, Halvor; Espeland, Sigurd Heiberg; Freitas, Carla; Knutsen, Jan Atle (Peer reviewed; Journal article, 2021)This article reviews a suite of studies conducted in a network of coastal Marine Protected Areas (MPAs) in Skagerrak, Southeast Norway. In 2006, Norway’s first lobster reserves were implemented, with the aim of protecting ... -
Small-scale genetic structure in a marine population in relation to water circulation and egg characteristics
Ciannelli, Lorenzo; Knutsen, Halvor; Olsen, Esben Moland; Espeland, Sigurd Heiberg; Asplin, Lars; Jelmert, Anders; Knutsen, Jan Atle; Stenseth, Nils Christian (Journal article; Peer reviewed, 2010-10)Until the last decade it was assumed that most marine species have pronounced gene flow over vast areas, largely because of their potential for dispersal during early life stages. However, recent genetic, modeling, and ... -
Spatial scale of genetic structuring in coastal cod Gadus morhua and geographic extent of local populations
Jorde, Per Erik; Knutsen, Halvor; Espeland, Sigurd Heiberg; Stenseth, Nils Christian (Journal article; Peer reviewed, 2007-08-07)We estimated the spatial scale of genetically distinguishable populations of coastal Atlantic cod Gadus morhua using microsatellite DNA markers. Significant overall heterogeneity in allele frequencies was found among 5 cod ... -
Stabilizing selection on Atlantic cod supergenes through a millennium of extensive exploitation
Sodeland, Marte; Jentoft, Sissel; Jorde, Per Erik; Mattingsdal, Morten; Albretsen, Jon; Kleiven, Alf Ring; Synnes, Ann-Elin; Espeland, Sigurd Heiberg; Olsen, Esben Moland; André, Carl; Stenseth, Nils Christian; Knutsen, Halvor (Peer reviewed; Journal article, 2022)Life on Earth has been characterized by recurring cycles of ecological stasis and disruption, relating biological eras to geological and climatic transitions through the history of our planet. Due to the increasing degree ...