• 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 ...
    • Judging a salmon by its spots: Environmental variation is the primary determinant of spot patterns in Salmo salar 

      Jørgensen, Katarina Mariann; Solberg, Monica Favnebøe; Besnier, Francois; Thorsen, Anders; Fjelldal, Per Gunnar; Skaala, Øystein; Malde, Ketil; Glover, Kevin (Journal article; Peer reviewed, 2018)
      In fish, morphological colour changes occur from variations in pigment concentrations and in the morphology, density, and distribution of chromatophores in the skin. However, the underlying mechanisms remain unresolved in ...
    • 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 ...
    • Mapping of fish spawning in the North Sea — Report of the KINO-2 project for 2018 

      Mateos-Rivera, Alejandro; Mozfar, Bahar; Skern-Mauritzen, Rasmus; Dahle, Geir; Wehde, Henning; Kleppe, Lisbeth; Sundby, Svein; Thorsen, Anders; Seliussen, Bjørghild Breistein; Asplin, Lars; Aguirre, Gaston Ezequiel; Isari, Stamatina; Krafft, Bjørn Arne (Rapport fra havforskningen, Research report, 2019)
      Increased and updated knowledge of reproductive strategies of fish is crucial to optimize the temporal and spatial planning for conducting seismic surveys; in order to reduce its potential negative ecosystems impacts. The ...
    • Mapping of Fish Spawning in the North Sea; Report of the “KINO-2” Project for 2019 

      Mateos-Rivera, Alejandro; Mozfar, Bahar; Skern, Rasmus; Dahle, Geir; Wehde, Henning; Kleppe, Lisbeth; Sundby, Svein; Thorsen, Anders; Asplin, Lars; Isari, Stamatina; Krafft, Bjørn Arne (Rapport fra havforskningen;2020 - 2, Research report, 2020)
      Increased and updated knowledge of reproductive strategies of fish is crucial to optimize the temporal and spatial planning for conducting seismic surveys; in order to reduce its potential negative ecosystems impacts. The ...
    • 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 ...
    • Ontogeny-Specific Skeletal Deformities in Atlantic Haddock Caused by Larval Oil Exposure 

      Olsvik, Pål Asgeir; Sørhus, Elin; Meier, Sonnich; Torvanger, Ingrid; Thorbjørnsen, Maja; Thorsen, Anders; Sørensen, Lisbet; Fjelldal, Per Gunnar; Karlsen, Ørjan; Guimaraes, Igo G.; Lie, Kai Kristoffer (Peer reviewed; Journal article, 2021)
      Bone deformities are one of the main effects of crude oil exposure in marine fish larvae. Craniofacial and jaw deformities, if severe enough, may restrict feeding and ultimately kill the developing larvae. This study aimed ...
    • 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 ...
    • 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 ...
    • Prey-specific gastric evacuation of Norwegian spring spawning herring (Clupea harengus) 

      Broms, Cecilie; Melle, Webjørn; Thorsen, Anders (ICES CM Documents;2004/P:39, Working paper, 2004)
      Gastric evacuation rates have earlier mainly been measured based on laboratory experiments. The aim of this study is to obtain information of gastric evacuation rates when the herring are feeding in their natural environment. ...
    • Production and verification of the first Atlantic salmon (Salmo salar L.) clonal lines 

      Hansen, Tom Johnny; Penman, David J.; Glover, Kevin; Fraser, Thomas; Vågseth, Tone; Thorsen, Anders; Sørvik, Anne Grete Eide; Fjelldal, Per Gunnar (Peer reviewed; Journal article, 2020)
      In several fish species homozygous and heterozygous clonal lines have been produced using gynogenetic and androgenetic techniques. These lines are standardized and can be reproduced over generations. In rainbow trout such ...
    • 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. ...
    • Skreitokt 2020 - Kartlegging av gytebestanden av skrei 2020 

      Korsbrekke, Knut; Thorsen, Anders (Rapport fra havforskningen;2020 - 32, Research report, 2020)
      Toktets akustiske dekning av torsk, hyse og sei dekket kystområdet fra 71° nord sørover til og med Røstbanken, samt Vestfjorden. Dekningen ga et mengdeanslag på 553 tusen tonn skrei (aldersgruppene 5+, modne individer). ...
    • Spawner quality effects on two measures of reproductive potential: have we been counting our eggs before they've hatched? 

      Marshall, C. Tara; Kjesbu, Olav Sigurd; Thorsen, Anders; Solemdal, Per (ICES CM documents, Working paper, 1999)
      Recent studies have found positive associations between recruitment and indices of spawner quality (condition) for stocks exhibiting an indeterminate relationship between recruitment and spawner biomass. This suggests ...
    • 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 ...
    • Systematic bias in estimates of reproductive potential of cod stocks: implications for stock/recruit theory and management 

      Marshall, C. Tara; Needle, Coby L.; Thorsen, Anders; Kjesbu, Olav Sigurd; Yaragina, Natalia A. (ICES CM documents, Working paper, 2005)
      Stock/recruit relationships, describing the relationship between the parental population and the number of offspring produced, are a central tool in population ecology. For fish populations the stock/recruit relationship ...
    • 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 ...
    • Triploid Atlantic salmon Salmo salar have a higher dietary phosphorus requirement for bone mineralization during early development 

      Sambraus, Florian; Hansen, Tom Johnny; Daae, Britt Sværen; Thorsen, Anders; Sandvik, Roar; Stien, Lars Helge; Fraser, Thomas; Fjelldal, Per Gunnar (Peer reviewed; Journal article, 2020)
      The effect of a dietary phosphorus regime in freshwater on vertebra bone mineralization was assessed in diploid and triploid Atlantic salmon, Salmo salar. Fish were fed either a low phosphorus (LP) diet containing 10.5 ...