Blar i Brage IMR på forfatter "Kjesbu, Olav Sigurd"
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Long-term changes in the total egg production of Norwegian spring-spawning herring Clupea harengus (L.)—Implications of variations in population structure and condition factor
Ndjaula, Hilkka O.N.; Nash, Richard D.M.; Slotte, Aril; Johannessen, Arne; Kjesbu, Olav Sigurd (Journal article; Peer reviewed, 2010-05)The reproductive potential of Norwegian spring-spawning herring (Clupea harengus) was estimated in terms of total egg production (TEP) for the period 1935–2005, using a model where spawning stock numbers (SSN)-, weight- ... -
Long-term interplay between harvest regimes and biophysical conditions may lead to persistent changes in age at sexual maturity of Northeast Arctic cod (Gadus morhua)
Carl Jacob, Rørvik; Bogstad, Bjarte; Ottersen, Geir; Kjesbu, Olav Sigurd (Peer reviewed; Journal article, 2022)This investigation commenced by constructing principal maturation schedule equations as a function of fishing mortality (F), key biophysical factors and a term attributed to fisheries-induced adaptive change (FIAC). Following ... -
Making use of Johan Hjort's “unknown” legacy: reconstruction of a 150-year coastal time-series on northeast Arctic cod (Gadus morhua) liver data reveals long-term trends in energy
Kjesbu, Olav Sigurd; Opdal, Anders Frugård; Korsbrekke, Knut; Devine, Jennifer A.; Skjæraasen, Jon Egil (Journal article; Peer reviewed, 2014-03-11)Hidden within the seminal 1914 publication by Johan Hjort, we find what is probably one of the first comprehensive teleost time-series ever published. The series is liver size and fat content of northeast Arctic (NEA) cod ... -
Management of transboundary and straddling fish stocks in the Northeast Atlantic in view of climate-induced shifts in spatial distribution
Gullestad, Peter; Sundby, Svein; Kjesbu, Olav Sigurd (Peer reviewed; Journal article, 2020)The introduction of 200 n.m. exclusive economic zones (EEZs) in the late 1970s required increased collaboration among neighbouring coastal states to manage transboundary and straddling fish stocks. The established agreements ... -
Mechanisms regulating oocyte recruitment and skippedspawning in Northeast Arctic cod (Gadus morhua L.)
Skjæraasen, Jon Egil; Kennedy, James; Thorsen, Anders; Fonn, Merete; Strand, Bente; Mayer, Ian; Kjesbu, Olav Sigurd (Journal article; Peer reviewed, 2009-09)To examine mechanisms that affect fecundity, atresia and skipped spawning in Northeast Arctic cod (Gadus morhua L.), we conducted an experiment where wild-caught cod (>60 cm) kept under restricted food regimes were subjected ... -
Mechanisms regulating oocyte recruitment and skippedspawning in Northeast Arctic cod (Gadus morhua L.)
Skjæraasen, Jon Egil; Kennedy, James; Thorsen, Anders; Fonn, Merete; Strand, Bente; Mayer, Ian; Kjesbu, Olav Sigurd (Journal article; Peer reviewed, 2009-09)To examine mechanisms that affect fecundity, atresia and skipped spawning in Northeast Arctic cod (Gadus morhua L.), we conducted an experiment where wild-caught cod (>60 cm) kept under restricted food regimes were subjected ... -
New insights in oocyte dynamics shed light on the complexities associated with fish reproductive strategies
Serrat, Alba; Saborido-Rey, Fran; Garcia-Fernandez, Cristina; Muñoz, Marta; Lloret, Josep; Thorsen, Anders; Kjesbu, Olav Sigurd (Journal article; Peer reviewed, 2019)Information on temporal variations in stock reproductive potential (SRP) is essential in fisheries management. Despite this relevance, fundamental understanding of egg production variability remains largely unclear due to ... -
Norsk-Arktisk torsk: Eggmenga gir bra varsel om årsklassestyrke
Marshall, C. Tara; Kjesbu, Olav Sigurd (Havforskningsnytt, Working paper, 2002) -
Overview of the EU fair project "STEREO" (Stock effects on recruitment relationships)
MacKenzie, Brian; Heath, Michael; Ådlandsvik, Bjørn; Backhaus, Jan O.; Bogstad, Bjarte; Gallego, Alejandro; Godø, Olav Rune; Gudmundsdottir, Asta; Harms, Ingo H.; Heilmann, J.P.; Jonsson, Sigurður; Kjesbu, Olav Sigurd; MacKenzie, Eddie; Marteinsdottir, Gudrun; Nielsen, Einar E.; Scott, Beth; Strugnell, G.; Stefánsson, Gunnar; Thorsen, Anders; Visser, Andre W.; Wright, Peter (ICES CM Documents;1999/Y:10, Working paper, 1999)The overall objective of the STEREO project is to improve the methodology for determining limit reference points for the biomass of exploited fish stocks. Limit reference points set boundaries which are intended to ... -
PAH and biomarker measurements in fish from condition monitoring in Norwegian waters in 2005 and 2008
Grøsvik, Bjørn Einar; Meier, Sonnich; Liewenborg, Birgitta; Nesje, Guri; Westrheim, Kjell; Fonn, Merete; Kjesbu, Olav Sigurd; Skarphéðinsdóttir, Halldóra; Klungsøyr, Jarle (ICES CM documents;2010/F:06, Working paper, 2010) -
Poleward spawning of Atlantic mackerel (Scomber scombrus) is facilitated by ocean warming but triggered by energetic constraints
dos Santos Schmidt, Thassya Christina; Slotte, Aril; Olafsdottir, Anna H.; Nøttestad, Leif; Jansen, Teunis; Jacobsen, Jan Arge; Bjarnason, Sigurvin; Lusseau, Susan Mærsk; Ono, Kotaro; Hølleland, Sondre Nedreås; Thorsen, Anders; Sandø, Anne Britt; Kjesbu, Olav Sigurd (Peer reviewed; Journal article, 2023)The Northeast Atlantic mackerel is an income breeder with indeterminate fecundity, spawning in multiple batches at optimal temperatures around 11°C in the upper water column during February–July along the continental shelf ... -
The potential importance of the paternal contribution to the ‘Stock Reproductive Potential’ of North-East Arctic cod (Gadus morhua)
Nash, Richard D.M.; Kjesbu, Olav Sigurd; Thorsen, Anders; Fonn, Merete; Krüger-Johnsen, Maria; Trippel, Ed (ICES CM documents, Working paper, 2005)Over the years there has been a growing interest in determining the real stock reproductive potential (SRP) as a means of understanding the dynamics of a fish population. For the purposes of assessment the spawning stock ... -
Preferential amplification of repetitive DNA during Next Generation Sequencing library creation of ancient DNA
Star, Bastiaan; Hansen, Marianne Helén Selander; Skage, Morten; Bradbury, Ian R.; Godiksen, Jane Amtoft; Kjesbu, Olav Sigurd; Jentoft, Sissel (Journal article; Peer reviewed, 2016-04-06)Repetitive microsatellite DNA forms a universal component of eukaryote genomes and specific biochemical properties of such repeat regions may influence the outcome of laboratory protocols. The Atlantic cod (Gadus ... -
Quantitative molecular detection of larval Atlantic herring (Clupea harengus) in stomach contents of Atlantic mackerel (Scomber scombrus) marks regions of predation pressure
Allen, Bridie; Ray, Jessica Louise; Tiedemann, Maik; Komyakova, Valeriya; Vikebø, Frode Bendiksen; Skaar, Katrine Sandnes; Stiasny, Martina H.; Folkvord, Arild; Nash, Richard David Marriott; Stenevik, Erling Kåre; Kjesbu, Olav Sigurd (Peer reviewed; Journal article, 2021)Mortality rates in the early life-history stages of fishes are generally high yet identifying the causes remain unclear. Faltering recruitment rates of Atlantic herring (Clupea harengus) in the Norwegian Sea indicate a ... -
Recruitment regime shifts and nonstationarity are widespread phenomena in harvestable stocks experiencing pronounced climate fluctuations
Ma, Shuyang; Huse, Geir; Ono, Kotaro; Nash, Richard David Marriott; Sandø, Anne Britt; Nedreaas, Kjell Harald; Hjøllo, Solfrid Sætre; Sundby, Svein; Clegg, Thomas L; Vølstad, Jon Helge; Kjesbu, Olav Sigurd (Peer reviewed; Journal article, 2023)Methods to reliably identify jump discontinuities in biological time series and to assess the specific contribution of various covariates are rapidly progressing. Here, we took advantage of these statistical improvements ... -
Relationship between atresia, fish size and condition in Icelandic cod (Gadus morhua L.)
Hardardottir, Kristin; Kjesbu, Olav Sigurd; Marteinsdottir, Gudrun (ICES CM documents, Working paper, 2001)Cod is a determinate spawner, with a high potential fecundity. That is, a large definite number of oocytes start maturing prior to spawning. Environmental factors, such as water temperature and food availability have ... -
Report of the working group on modern approaches to assess maturity and fecundity of warm- and coldwater fish and squids
Kjesbu, Olav Sigurd; Hunter, John R.; Witthames, Peter R. (Fisken og havet, Research report, 2003)A workshop was held in Bergen in September 2001 to improve the overall quality of reproduction data used in assessments of marine stocks and egg production surveys by reviewing 1) present practices and 2) establishing a ... -
The reproductive cycle of female Ballan wrasse Labrus bergylta in high latitude, temperate waters
Muncaster, S.; Andersson, Eva; Kjesbu, Olav Sigurd; Taranger, Geir Lasse; Skiftesvik, Anne Berit; Norberg, Birgitta (Journal article; Peer reviewed, 2010-08)This 2 year study examined the reproductive cycle of wild female Ballan wrasse Labrus bergylta in western Norway as a precursor to captive breeding trials. Light microscopy of ovarian histology was used to stage gonad ... -
Sensitivity of potential recruitment to stock structure in the presence of temporally varying survival.
Scott, Beth; Marteinsdottir, Gudrun; Wright, Peter; Kjesbu, Olav Sigurd (ICES CM documents, Working paper, 1999)In this paper we discuss the results-of a modelling study which quantifies differences in the number of potential recruits produced from a range of age-structured populations over a spawning season with temporally varying ... -
Size of spawning Arcto-Norwegian cod (Gadus morhua L.) and the effects on their eggs and early larvae
Solemdal, Per; Bergh, Øivind; Dahle, Geir; Falk-Petersen, Inger-Britt; Fyhn, Hans Jørgen; Grahl-Nielsen, Otto; Haaland, J.M.; Kjesbu, Olav Sigurd; Løken, Sissel; Opstad, Ingegjerd; Pedersen, Torstein; Skiftesvik, Anne Berit; Thorsen, Anders (ICES CM Documents;1993/G:41, Working paper, 1993)Using a new method for determining the stage of spawning in batch spawners, a positive correlation between the length of Arcto-Norwegian cod females, having spawned 25-75% of their eggs, and the egg diameter was established. ...