Blar i ICES CM documents authored by IMR scientists (1949-2011) på forfatter "Kjesbu, Olav Sigurd"
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The application of tank experiments to the study of reproductive potential in teleosts using Gadus morhua as a test model
Witthames, Peter R.; Andersen, T.E.; Kjesbu, Olav Sigurd (ICES CM documents, Working paper, 2000)Age-based population assessments (VPA) have often failed to show a clear relationship between spawning stock biomass and either recruitment or biomass estimated from annual egg production. Recent work has shown that the ... -
Bio-physical properties of Norwegian coastal cod eggs
Jung, Kyung-Mi; Sundby, Svein; Thorsen, Anders; Folkvord, Arild; Kjesbu, Olav Sigurd (ICES CM documents;2009/C:11, Working paper, 2009)Vertical distribution of fish eggs and larvae is a key factor for transport and retention of the offspring, and for problems linked to mixing/separation between populations, and hence for mechanism maintaining genetic ... -
A comparison of egg quality and larval viability between cultured coastal cod and wild arcto-norwegian cod
Solemdal, Per; Kjesbu, Olav Sigurd; Opstad, Ingegjerd; Skiftesvik, Anne Berit; Birkeland, R.; Bratland, Per; Fonn, Merete (ICES CM documents;1991/F:41;, Working paper, 1991)Experiments on cod eggs revealed an inverse relationship between egg diameter and mortality. Further, larvae hatching from small eggs showed a redeuced feeding ability. Other methods to characterice larval viability ... -
Demonstration of maternal effects of Atlantic cod: Combining the use of unique mesocosm and novel molecular techniques – A new EU-project
Svåsand, Terje; Ajiad, Adnan Mosa; Dahle, Geir; Jakobsen, Tore; Kjesbu, Olav Sigurd; Moksness, Erlend; Otterå, Håkon; Solemdal, Per; Thorsen, Anders (ICES CM documents, Working paper, 2000)One of the effects of fishing is a reduction in average age and size in exploited fish stocks, leading to an increasing proportion of recruit spawners in the stock. Current management practice assumes equal viability of ... -
Egg mortality in recruit- and repeat-spawning cod: an experimental study
Solemdal, Per; Kjesbu, Olav Sigurd; Fonn, Merete (ICES CM documents, Working paper, 1995)Experiments on the reproduction of individual Norwegian coastal cod and for the Arcto-Norwegian cod were conducted during the years 1982-92, and the year 1995 respectively. The experimental fish used were held in captivity ... -
Estimation of potential and realised fecundity of fish
Thorsen, Anders; Kjesbu, Olav Sigurd; Witthames, Peter R. (ICES CM documents, Working paper, 2005) -
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 “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 ... -
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 ... -
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 ... -
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) -
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 ... -
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 ... -
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. ... -
Some like it cold – Consequence of warming seas for the distribution of large bodied fish
Höffle, Hannes; Kjesbu, Olav Sigurd (ICES CM documents;2014/M:07, Conference object, 2014-09-15) -
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 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 ...