Blar i Brage IMR på forfatter "Kjesbu, Olav Sigurd"
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The fate of vitellogenic follicles in experimentally monitored Atlantic cod Gadus morhua (L.): Application to stock assessment
Witthames, Peter R.; Thorsen, Anders; Kjesbu, Olav Sigurd (Journal article; Peer reviewed, 2010-05)In this paper we report on the fate of vitellogenic follicles (VF) as either alpha atretic follicles (αF) or post-ovulatory follicles (POFs) using histology and captive Atlantic cod (Gadus morhua) in three experiments. In ... -
Fecundity and growth of Atlantic cod (Gadus morhua L.) along a latitudinal gradient
Thorsen, Anders; Witthames, Peter R.; Marteinsdottir, Gudrun; Nash, Richard D.M.; Kjesbu, Olav Sigurd (Journal article; Peer reviewed, 2010-05)Some fish species have wide distribution areas that span very different habitats. In this investigation we have studied Atlantic cod (Gadus morhua), which is an example of such a species, to demonstrate how this may have ... -
Fecundity and maturity of cod (Gadus morhua L.) from northern Norway
Kjesbu, Olav Sigurd (ICES CM Documents;1988/G:28, Working paper, 1988)The fecundity was determined for cod caught during March 1986 and 1987 in the region Lofoten - Malangsgrunnen, northern Norway. No significant difference in fecundity appeared between the two years. -
Fecundity of Greenland halibut (Reinhardtius hippoglossoides) in the north east Arctic
Gundersen, Agnes C.; Kjesbu, Olav Sigurd; Stene, Anne; Nedreaas, Kjell Harald (ICES CM documents, Working paper, 1998) -
From gametogenesis to spawning: How climate-driven warming affects teleost reproductive biology
Alix, Maud; Kjesbu, Olav Sigurd; Anderson, Kelli C. (Peer reviewed; Journal article, 2020)Ambient temperature modulates reproductive processes, especially in poikilotherms such as teleosts. Consequently, global warming is expected to impact the reproductive function of fish, which has implications for wild ... -
From “where” and “when” to “what” and “why”: archival tags for monitoring “complex” behaviours in fish.
Metcalfe, Julian D.; Wilson, R.P.; Kjesbu, Olav Sigurd; Challiss, M.J.; Gleiss, A.; Skjæraasen, Jon Egil; Clarke, S. (ICES CM documents;2009/B:04, Working paper, 2009)Understanding the movements (“where” and “when”) and behaviour (“what” and, hopefully, “why”) of individuals and populations is key to answering fundamental questions in fish ecology. The use of archival tags in telemetry ... -
Genomic stability through time despite decades of exploitation in cod on both sides of the Atlantic
Pinsky, Malin L; Eikeset, Anne Maria; Helmerson, Cecilia; Bradbury, Ian R.; Bentzen, Paul; Morris, Corey; Gondek, Agata; Baalsrud, Helle Tessand; Brieuc, Marine Servane Ono; Kjesbu, Olav Sigurd; Godiksen, Jane Aanestad; Barth, Julia Maria Isis; Matschiner, Michael; Stenseth, Nils Christian; Jakobsen, Kjetill Sigurd; Jentoft, Sissel; Star, Bastiaan (Peer reviewed; Journal article, 2021)The mode and extent of rapid evolution and genomic change in response to human harvesting are key conservation issues. Although experiments and models have shown a high potential for both genetic and phenotypic change in ... -
Half a century of high-latitude fisheries oceanography research on the "recruitment problem" in Northeast Arctic cod (Gadus morhua)
Kjesbu, Olav Sigurd; Tiedemann, Maik; Alix, Maud; Thorsen, Anders; Sundby, Svein (Peer reviewed; Journal article, 2023)Predicting recruitment in a reliable fashion is a great challenge within operational fisheries advice. Here, we consulted the unique but undercommunicated IMR Cod Larva Project (1975–1990), its spin-offs, placed in an ... -
Highly mixed impacts of near-future climate change on stock productivity proxies in the North East Atlantic
Kjesbu, Olav Sigurd; Sundby, Svein; Sandø, Anne Britt; Alix, Maud; Hjøllo, Solfrid Sætre; Tiedemann, Maik; Skern-Mauritzen, Mette; Junge, Claudia; Fossheim, Maria; Broms, Cecilie; Søvik, Guldborg; Zimmermann, Fabian; Nedreaas, Kjell Harald; Eriksen, Elena; Höffle, Hannes; Hjelset, Ann Merete; Kvamme, Cecilie; Reecht, Yves; Knutsen, Halvor; Aglen, Asgeir; Albert, Ole Thomas; Berg, Erik; Bogstad, Bjarte; Durif, Caroline; Halvorsen, Kim Aleksander Tallaksen; Høines, Åge Sigurd; Hvingel, Carsten; Johannesen, Edda; Johnsen, Espen; Moland, Even; Myksvoll, Mari Skuggedal; Nøttestad, Leif; Olsen, Erik Joel Steinar; Skaret, Georg; Skjæraasen, Jon Egil; Slotte, Aril; Staby, Arved; Stenevik, Erling Kåre; Stiansen, Jan Erik; Stiasny, Martina H.; Sundet, Jan Henry; Vikebø, Frode Bendiksen; Huse, Geir (Peer reviewed; Journal article, 2021)Impacts of climate change on ocean productivity sustaining world fisheries are predominantly negative but vary greatly among regions. We assessed how 39 fisheries resources—ranging from data-poor to data-rich stocks—in the ... -
How variable is the fecundity within and between cod stocks?
Lambert, Yvan; Kjesbu, Olav Sigurd; Kraus, G.; Marteinsdottir, Gudrun; Thorsen, Anders (ICES CM documents, Working paper, 2005)Stock reproductive potential is determined by the number of fish at age, sex ratio, proportion of mature female at age and fecundity. Fecundity data, which are fundamental in estimating egg production are not collected ... -
Hunnenes modningssyklus hos kolmule Micromesistius poutassou (Risso, 1810) : en stadiebestemmelse av ovarier fra Bjørnøya-Norskekysten i mars 1982
Kjesbu, Olav Sigurd (Master thesis, 1982) -
Increasing temperature and prey availability affect the growth and swimming kinematics of Atlantic herring (Clupea harengus) larvae
Allan, Bridie Jean Marie; Browman, Howard; Shema, Steven; Skiftesvik, Anne Berit; Folkvord, Arild; Durif, Caroline; Kjesbu, Olav Sigurd (Peer reviewed; Journal article, 2022)Climate change will increase the magnitude and duration of warming events and the variability in the phenology and abundance of available prey to the early life stages of fish. These factors influence physiological, ... -
Interaction and integration of observation and models – the EcoFish approach
Godø, Olav Rune; Hauge, Kjellrun Hiis; Hjøllo, Solfrid Sætre; Iversen, Svein A.; Kjesbu, Olav Sigurd; Nash, Richard D.M.; Svendsen, Einar (ICES CM documents;2007/R:14, Working paper, 2007)Ecosystem approach to fisheries management demand new scientific approaches and tools. The EcoFish project is a recently established project that pursues the challenges set by the new approach. It aims at supporting ... -
Is it possible to photoperiod manipulate spawning time in planktivorous fish ? A long-term experiment on Atlantic herring
dos Santos Schmidt, Thassya Christina; Berg, Florian; Folkvord, Arild; Pires, Alessandra M.A.; Komyakova, Valeriya; Tiedemann, Maik; Kjesbu, Olav Sigurd (Peer reviewed; Journal article, 2022)The oocyte development (vitellogenesis) of individual fish is highly dependent upon their physiology which is influenced by both intrinsic and extrinsic factors. Thus, if individuals encounter poor biophysical conditions, ... -
Latitudinally distinct stocks of Atlantic cod face fundamentally different biophysical challenges under on-going climate change
Kjesbu, Olav Sigurd; Alix, Maud; Sandø, Anne Britt; Strand, Espen; Wright, Peter J.; Johns, David G.; Thorsen, Anders; Marshall, C. Tara; Bakkeplass, Kjell Gunnar; Vikebø, Frode Bendiksen; Myksvoll, Mari Skuggedal; Ottersen, Geir; Allan, Bridie Jean Marie; Fossheim, Maria; Stiansen, Jan Erik; Huse, Geir; Sundby, Svein (Peer reviewed; Journal article, 2023)The reproductive success of marine ectotherms is especially vulnerable in warming oceans due to alterations in adult physiology, as well as embryonic and larval survival prospects. These vital responses may, however, differ ... -
Latitudinally distinct stocks of Atlantic cod face fundamentally different biophysical challenges under on-going climate change
Kjesbu, Olav Sigurd; Alix, Maud; Sandø, Anne Britt; Strand, Espen; Wright, Peter J.; Johns, David G.; Thorsen, Anders; Marshall, C. Tara; Bakkeplass, Kjell Gunnar; Vikebø, Frode Bendiksen; Myksvoll, Mari Skuggedal; Ottersen, Geir; Allan, Bridie Jean Marie; Fossheim, Maria; Stiansen, Jan Erik; Huse, Geir; Sundby, Svein (Peer reviewed; Journal article, 2023)The reproductive success of marine ectotherms is especially vulnerable in warming oceans due to alterations in adult physiology, as well as embryonic and larval survival prospects. These vital responses may, however, differ ... -
Levermengden viser fiskebestandens rekrutteringspotensial
Marshall, C. Tara; Kjesbu, Olav Sigurd (Havforskningsnytt, Working paper, 2000) -
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- ...