Browsing Brage IMR by Author "Kjesbu, Olav Sigurd"
Now showing items 1-20 of 57
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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 ... -
Condition monitoring in the water column 2008: Oil hydrocarbons in fish from Norwegian waters
Grøsvik, Bjørn Einar; Meier, Sonnich; Liewenborg, Birgitta; Nesje, Guri; Westrheim, Kjell; Fonn, Merete; Kjesbu, Olav Sigurd; Klungsøyr, Jarle (Rapport fra Havforskningen;Nr.2-2009, Working paper, 2009-06)The objectives for this study have been: 1. Measure NPD/PAH in haddock liver from the Egersund Bank, the Halten Bank andthe Barents Sea. 2. Determine to what extent fish from the oil installation areas at Tampen and the ... -
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 ... -
Do eggs collected in egg surveys accurately reflect adult fecundities?
Höffle, Hannes; Vikebø, Frode Bendiksen; Kjesbu, Olav Sigurd (Conference object, 2014) -
Effects of ration on the maturation and fecundity in captive Atlantic herring (Clupea harengus)
Ma, Y.; Kjesbu, Olav Sigurd; Jørgensen, Terje (Journal article; Peer reviewed, 1998)We examined the effects of amount of food on vitellogenic oocyte size and number (fecundity) between two experimental groups of Atlantic herring (Clupea harengus) kept in separate but identical compartments of a large ... -
Egg buoyancy variability in local populations of Atlantic cod (Gadus morhua)
Jung, Kyung-Mi; Folkvord, Arild; Kjesbu, Olav Sigurd; Agnalt, Ann-Lisbeth; Thorsen, Anders; Sundby, Svein (Journal article; Peer reviewed, 2012-06-29)Previous studies have found strong evidences for Atlantic cod (Gadus morhua) egg retention in fjords, which are caused by the combination of vertical salinity structure, estuarine circulation, and egg specific gravity, ... -
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 ... -
Environmental and demographic Controls on the distribution of North East Arctic cod spawning around the Lofoten Islands
Höffle, Hannes; Johannessen, Magnus Einar; Korsbrekke, Knut; Bakkeplass, Kjell; Kjesbu, Olav Sigurd (Conference object, 2013-10)When seeking a location for spawning, fish appear to be under the influence of two groups of factors. Firstly, environmental cues such as temperature and salinity. Secondly, interactions with other individuals, like ... -
Estimation of potential and realised fecundity of fish
Thorsen, Anders; Kjesbu, Olav Sigurd; Witthames, Peter R. (ICES CM documents, Working paper, 2005) -
Experimental Parameterisation of Principal Physics in Buoyancy Variations of Marine Teleost Eggs
Jung, Kyung-Mi; Folkvord, Arild; Kjesbu, Olav Sigurd; Sundby, Svein (Journal article; Peer reviewed, 2014-08-14)It is generally accepted that the high buoyancy of pelagic marine eggs is due to substantial influx of water across the cell membrane just before ovulation. Here we further develop the theoretical basis by applying laboratory ... -
Extent and ecological importance of escape through spawning in sea-cages for Atlantic cod
Uglem, Ingebrigt; Knutsen, Øyvind; Kjesbu, Olav Sigurd; Hansen, Øyvind J.; Mork, Jarle; Bjørn, Pål Arne; Varne, Rebekka; Nilsen, Rune; Ellingsen, Ingrid; Dempster, Tim (Journal article; Peer reviewed, 2012-11-14)The culture of certain fish species to sizes at which they can reproduce has led to the escape of fertilised eggs or ‘escape through spawning’. To investigate the extent and ecological importance of spawning in sea-cages ... -
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 ... -
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 “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 ...