Blar i Articles på forfatter "Kjesbu, Olav Sigurd"
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Linking the dynamic organization of the ovary with spawning dynamics in pelagic fishes
Charitonidou, Katerina; Kjesbu, Olav Sigurd; Nunes, Cristina; Angélico, Maria Manuel; Dominguez-Petit, Rosario; Garabana, Dolores; Ganias, Konstantinos (Peer reviewed; Journal article, 2022)The link between the dynamic organization of the ovary and spawning dynamics was investigated in pelagic fishes with indeterminate fecundity. Αn array of laboratory methods and statistical approaches was applied to samples ... -
Liver energy, atresia and oocyte stage influence fecundity regulation in Northeast Arctic cod
Skjæraasen, Jon Egil; Nash, Richard D.M.; Kennedy, James; Thorsen, Anders; Nilsen, Trygve; Kjesbu, Olav Sigurd (Journal article; Peer reviewed, 2010-04-08)Marine ecosystems are changing; global warming-induced increases in water temperatures and fishing have caused truncated age structures and small sizes at maturity in many stocks. This may affect both populations’ total ... -
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 ... -
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 ... -
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 ... -
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 ... -
Skipped spawning in Northeast Arctic haddock Melanogrammus aeglefinus
Skjæraasen, Jon Egil; Korsbrekke, Knut; Nilsen, Trygve; Fonn, Merete; Kjesbu, Olav Sigurd; Dingsør, Gjert Endre; Nash, Richard David Marriott (Journal article; Peer reviewed, 2015-04-22) -
Some characteristics of sperm motility in European hake (Merluccius merluccius, L., 1758)
Groison, A.-L.; Fauvel, C.; Suquet, M.; Kjesbu, Olav Sigurd; Le Coz, J.R.; Mayer, Ian; Cosson, J. (Journal article; Peer reviewed, 2010-09-17)The objective of this paper is to characterize some of the sperm motility parameters in European hake (Merluccius merluccius), which is considered to be a species with aquaculture potential. The total ATP, ADP and AMP ... -
Stereological calibration of the profile method to quickly estimate atresia levels in fish
Kjesbu, Olav Sigurd; Fonn, Merete; Gonzáles, Barbara Dunia; Nilsen, Trygve (Journal article; Peer reviewed, 2010-05)The (physical) ‘disector method’, a frequently cited stereological technique, has so far received little attention within fish fecundity studies, although it can be used to provide unbiased, assumption-free data on levels ... -
Synergies between climate and management for Atlantic cod fisheries at high latitudes
Kjesbu, Olav Sigurd; Bogstad, Bjarte; Devine, Jennifer A.; Gjøsæter, Harald; Howell, Daniel; Ingvaldsen, Randi; Nash, Richard D.M.; Skjæraasen, Jon Egil (Journal article; Peer reviewed, 2014-02-18)The widespread depletion of commercially exploited marine living resources is often seen as a general failure of management and results in criticism of contemporary management procedures. When populations show dramatic and ... -
Systematic bias in estimates of reproductive potential of an Atlantic cod (Gadus morhua) stock: implications for stock–recruit theory and management
Marshall, C. Tara; Needle, Coby L.; Thorsen, Anders; Kjesbu, Olav Sigurd; Yaragina, Natalia A. (Journal article; Peer reviewed, 2006)Stock–recruit relationships that use spawning stock biomass (SSB) to represent reproductive potential assume that the proportion of SSB composed of females and the relative fecundity (number of eggs produced per unit ... -
The legacy of Johan Hjort: Challenges and critical periods ‒ past, present and future
Kjesbu, Olav Sigurd; Hubbard, Jennifer; Suthers, Iain M.; Schwach, Vera (Peer reviewed; Journal article, 2020)The 150th anniversary of Johan Hjort’s birth was celebrated by a symposium held in Bergen on 12–14 June 2019 to take a broad perspective on the origins of, and developments in, fisheries science and thereby examine current ... -
The North Atlantic spring-bloom system - where the changing climate meets the winter dark
Sundby, Svein; Drinkwater, Ken; Kjesbu, Olav Sigurd (Journal article; Peer reviewed, 2016-03-15)The North Atlantic with its spring-bloom ecosystem has its particular responses to climate change, many of them different from the other parts of the world's oceans. The system is strongly influenced by anthropogenic climate ... -
Thermal dynamics of ovarian maturation in Atlantic cod (Gadus Morhua)
Kjesbu, Olav Sigurd; Righton, David; Krüger-Johnsen, Maria; Thorsen, Anders; Michalsen, Kathrine; Fonn, Merete; Witthames, Peter R. (Journal article; Peer reviewed, 2010-03)The timing and success of spawning in marine fish are of fundamental importance to population persistence and distribution and, for commercial species, sustainability. Their physiological processes of reproduction are ...