• Abundance estimation of Northeast Atlantic mackerel based on tag recapture data - A useful tool for stock assessment? 

      Tenningen, Maria; Slotte, Aril; Skagen, Dankert W. (Journal article; Peer reviewed, 2010-10)
      In the present study we utilize tag recapture data to estimate year class abundance and spawning stock biomass of mackerel (Scomber scombrus L.) in the Northeast Atlantic for the period 1986–2008. On average 20,000 jigged ...
    • Assessing natural mortality of anchovy from surveys' population and biomass estimates 

      Uriarte, A.; Ibaibarriaga, Leire; Abaunza, Pablo; Pawlosky, L.; Massé, Jacques; Petitgas, Pierre; Santos, M. B.; Skagen, Dankert W. (ICES CM documents;2010/C:12, Working paper, 2010)
      In ordinary catch at age models, natural mortality conditions and determines the catchabilities at age obtained for the surveys which tune the assessments. For the same reason, inferring the Natural mortality of a fish ...
    • CEC - a VPA for cod in the Barents Sea with cod - cod cannibalism 

      Skagen, Dankert W.; Bogstad, Bjarte; Mehl, Sigbjørn (Working paper, 1990)
    • Changes on horse mackerel (Trachurus trachurus) catch distribution in the Northeast Atlantic 

      Borges, Maria Fatima; Silva, Alexandra; Abaunza, Pablo; Eltink, A.; Lucio, Paulino; Walsh, Martin; Poulard, Jean-Charles; Casey, John; Iversen, Svein A.; Skagen, Dankert W.; Sanchez, Francisco (ICES CM Documents;1996/S:26, Working paper, 1996)
      The distributions of international commercial catch data were mapped by ICES rectangle and quarter from 1983-1994. These indicate a northward expansion of horse mackerel distribution in the Northeast Atlantic since 1987. ...
    • Comparison of Uncertainty Estimates in the Short Term Using Real Data 

      Gavaris, S.; Patterson, K. R.; Lewy, P.; Mesnil, Benoit; Punt, A. E.; Cook, R. M.; Kell, Laurence T.; O’Brien, C. M.; Restrepo, V. R.; Skagen, Dankert W.; Stefánsson, Gunnar (ICES CM documents, Working paper, 2000)
      In response to increased interest in the Precautionary Approach, various approaches have been applied to characterize the uncertainty of fisheries assessment projection results. Using three case studies, a comparison of ...
    • Cruise summary report [18/10 - 8/11, 2004] 

      Korneliussen, Rolf J.; Skagen, Dankert W.; Slotte, Aril ([Toktrapport/Havforskningsinstituttet];Nr. 3 - 2005, Working paper, 2005)
    • Do Different Methods Provide Accurate Probability Statements in the Short Term? 

      Restrepo, V. R.; Patterson, K. R.; Darby, Chris; Gavaris, S.; Kell, Laurence T.; Lewy, P.; Mesnil, Benoit; Punt, A. E.; Cook, R. M.; O’Brien, C. M.; Skagen, Dankert W.; Stefánsson, Gunnar (ICES CM documents, Working paper, 2000)
      The performance of uncertainty estimation procedures was evaluated with respect to accuracy. A confidence statement is said to be accurate if the confidence point achieves the desired probability coverage. A Monte Carlo ...
    • Evaluation of candidate management plans, with reference to North-East Arctic Cod 

      Skagen, Dankert W.; Bogstad, Bjarte; Sandberg, Per; Røttingen, Ingolf (ICES CM documents, Working paper, 2003)
      We here discuss the scope, nature and quality standards of simulation models that may be used in order to evaluate proposed or candidate management plans, including their parameters (reference points). A recently proposed ...
    • Geographic variability of sardine dynamics in the Iberian Biscay region 

      Silva, Alexandra; Skagen, Dankert W.; Uriarte, A.; Massé, Jacques; Santos, M. B.; Marques, V.; Carrera, P.; Beillois, P.; Pestana, G.; Porteiro, C.; Stratoudakis, Y. (Journal article; Peer reviewed, 2009-04)
      The spatio-temporal variability in the distribution, demographic structure, recruitment, and mortality of sardine within the Iberian Biscay region is described using area-disaggregated data collected during acoustic surveys ...
    • Growth patterns in the North Sea and western mackerel in Norwegian catches 1960- 85 

      Skagen, Dankert W. (ICES CM Documents;1989/H:21, Working paper, 1989)
      Length, weight and age in random samples from Norwegian catches of' mackerel from 1960 to 1985 have been reviewed. A standard growth curve was constructed by applying a modified von Bertalanffy equation to all data. The ...
    • Harvest control rules and changing productivity: the working example of North Sea herring 

      Dickey-Collas, Mark; Skagen, Dankert W.; Simmonds, E. John (ICES CM documents, Working paper, 2006)
      North Sea herring is managed by the EU and Norway through a harvest control rule where target fishing mortalities are changed if the estimated SSB falls below a trigger biomass million tonnes). This management agreement ...
    • Ichthyophonus hoferi disease in the herring in Norwegian waters 

      Hjeltnes, Brit K.; Skagen, Dankert W. (ICES CM Documents;1992/H:27, Working paper, 1992)
      After the discovery of I. hoferi disease in Norwegian spring spawning herring in summer 1991, a program for systematic surveillance of the disease in the herring in Norwegian waters was developed. The programme, which ...
    • Influence of climate on recruitment and migration of fish stocks in the North Sea 

      Svendsen, Einar; Aglen, Asgeir; Iversen, Svein A.; Skagen, Dankert W.; Smedstad, Odd M. (ICES CM Documents;1991/H:12, Working paper, 1991)
      For several decades one of the prime targets within fishery science has been to be able to understand and explain the great variability in the success of survival from egg to mature fish. One of the reasons why such effort ...
    • Management with sparse data 

      Skagen, Dankert W.; Dankel, Dorothy Jane (ICES CM documents;2007/O:22, Working paper, 2007)
      We consider a management that aims at controlling the removal from the stock, guided by a perception of the state of the stock derived from limited data that does not allow an ordinary analytic assessment. In simulation ...
    • Migration of western mackerel to the North Sea 1973 - 1988 

      Iversen, Svein A.; Skagen, Dankert W. (ICES CM Documents;1989/H:20, Working paper, 1989)
      The latest years, it is evident that most of the mackerel present in the North Sea belongs to the Western stock, since the yearly catches by far exceed the presumed size of the North Sea stock. The Norwegian tagging ...
    • Miljøinformasjon i bestandsvurdering og rådgivning 

      Huse, Geir; Bogstad, Bjarte; Hauge, Kjellrun Hiis; Korsbrekke, Knut; Loeng, Harald; Michalsen, Kathrine; Skagen, Dankert W.; Stiansen, Jan Erik; Sundby, Svein; Svendsen, Einar; Tjelmeland, Sigurd; Toresen, Reidar (Fisken og havet, Research report, 2007)
      This report summarizes the work of an internal working group appointed by the Institute of Marine Research's management group to evaluate inclusion of environmental parameters in stock evaluation. The report discusses ...
    • Report of the 1991 ICES coordinated acoustic survey of herring stocks in ICES divisions VIa IVa and IVb 

      Simmonds, E. John; Reid, David; Aglen, Asgeir; Skagen, Dankert W.; Corten, A. (ICES CM Documents;1992/H:35, Working paper, 1992)
    • Size and condition of mackerel in research vessel trawl hauls versus commercial purse seine catches: implications for acoustic biomass estimation 

      Slotte, Aril; Skagen, Dankert W.; Iversen, Svein A. (ICES CM documents, Working paper, 2006)
      In September, after the summer feeding has ceased, the Northeast Atlantic mackerel (Scomber scombrus) stock tends to aggregate in ICES Area IVa before they start to migrate southwards in December-February towards the ...
    • Size of mackerel in research vessel trawls and commercial purse-seine catches: implications for acoustic estimation of biomass 

      Slotte, Aril; Skagen, Dankert W.; Iversen, Svein A. (Journal article; Peer reviewed, 2007-04)
      In September after summer feeding has ceased, Northeast Atlantic mackerel (Scomber scombrus) tend to aggregate in ICES Area IVa before starting to migrate south towards the spawning grounds, between December and February. ...
    • Stock prediction using stochastic recruitment numbers with empirical stock-dependent distribution 

      Skagen, Dankert W. (ICES CM Documents;1991/H:28, Working paper, 1991)
      Probability distributions for the recruitment, conditional on the spawning stock biomass (SSB) were made using a kernel method. Predictions were made with recruitments according to these distributions for 10 years, using ...