Ecosystem-Economic Interactions in the Norwegian Sea: Analysis and Management

The EINSAM project investigates the merits of ecosystem-base management in relation to exploitation at different trophic levels. The project aims to build a technically feasible and scientifically sound management framework that includes:

1. Building models of ecosystem-economic interactions and developing methods to anchor models in real-world applications.

2. Analyzing models with respect to decisions under uncertainty and develop comparative analysis tools.

3. Providing detailed policy analyses that in particular discusses implications at both the ecological and economic level. 

The management framework is meant to be operational in the sense that when applied to real-world cases, it provides relevant high-level decision rules or management plans. The Norwegian Sea provides an ideal situation to which the framework will be applied. Not only is it a relevant case in that the Norwegian government seeks to develop a holistic and ecosystem-based management plan for the ecoregion, but the research team also has relevant empirical and theoretical expertise. Further, the Norwegian Sea ecosystem is already exploited at several trophic levels, and particularly the exploitation at lower levels is poised to develop and become commercially viable in the relative near future. The EINSAM project is thus of both political and scientific interest.



The historically important fisheries in the Norwegian Sea are the fisheries for blue whiting and Norwegian spring spawning herring. In later years, the mackerel fishery has also become large and important. These three species are all regarded as pelagic and while there probably are some predation-type interactions between for example herring and blue whiting, the pelagic species can be roughly regarded as belonging to the same trophic level. The zooplankton C. finmarchicus belong to a lower trophic level, and is probably the most important link between the primary production in the ecoregion and higher trophic levels. 

Calanus finmarchicus in the Norwegian Sea
The copepod Calanus finmarchicus is the dominant species of the meso zooplankton in the Norwegian Sea (Melle et al. 2004). The species is largely herbivorous and constitutes an important link between the phytoplankton to the higher trophic levels in the Norwegian Sea food chain (Aksnes and Blindheim 1996, Melle et al. 2004). The C. finmarchicus is vital to many of the planktivorous fish species including Norwegian spring spawning (NSS) herring (Clupea harengus L.), blue whiting (Micromesistius poutassou, Risso), and mackerel (Scomber scombrus L.). In addition to these migrating predators, there are large standing stocks of invertebrates and mesopelagic fish that feed on different stages of Calanus (Dalpadado et al. 1998). Its life cycle consists of overwintering at depth, ascent towards the surface during early spring, maturation, and subsequent commencement of egg production prior to and during the spring phytoplankton bloom (Marshall and Orr 1955, Hirche 1996b). The juvenile generation remain in the upper waters during summer and may mature and reproduce within the season or build up fat reserves and descend for overwintering (Hirche 1996a).  

The shift between a deep and safe but unproductive habitat to a shallow and risky but productive habitat is important to the fitness of C. finmarchicus. The timing of the spring bloom is important for the ascent of C. finmarchicus (Hirche 1996a), and the peak of the spring bloom is often associated with the first copepodite stage (Melle et al. 2004). Kaartvedt (2000) argues that predation from planktivorous fish is a key driver in the timing of the descent to overwintering, and causes the Norwegian Sea population of C. finmarchicus to descend in June at a time of relatively high phytoplankton production. Clearly, the timing of ascent and descent and its match-mismatch with the presence of pelagic species is linked to a trade-off between growth, survival and reproduction.

Models of C. finmarchicus population dynamics have developed from one-dimensional individual based models, via three-dimensional individual based models, to spatial models coupled with biophysical ocean models (Gentleman 2002 provides a review of relevant models). The broad impact of C. finmarchicus on other species makes it a key specie in the Norwegian Sea ecosystem. Of particular interest for the EINSAM project are the ability of the spatial and population models to generate prey fields for fish larvae and planktivorous fish and thereby to add to the understanding of the match-mismatch process between the C. finmarchicus life cycle and its role as feed for pelagic fishes.  

The three-dimensional biophysical model can also be used as a basis for parameterisation of aggregated population models that can be implemented in bioeconomic management models in order to investigate the potential influence of C. finmarchicus on optimal harvest strategies for interacting, commercial fisheries.

The pelagic fisheries
The Northeast Atlantic is home to some of the richest fishing grounds in the world. Historically, blue whiting and Norwegian spring spawning herring have been the largest stocks but the fishery for mackerel has also become important. The stocks are all pelagic and require extraordinary care when modelling production (Steinshamn 2011, Ekerhovd and Kvamsdal 2013). The stocks are also all straddling; they are harvested both in the coastal states Exclusive Economic Zones (EEZs) and on the high seas (Bjørndal 2009).

The fishery for Norwegian spring spawning herring is managed by a cooperative agreement among all coastal states involved (Bjørndal and Munro 2012). For mackerel, there is currently no international agreement, and the fishery is unsustainable (Bjørndal and Ekerhovd 2013). Prior to 2006, there was no cooperative agreement for the blue whiting fishery. For a time it was the largest fishery in the North East Atlantic, with a maximum annual catch in 2004 of about 2.4 million tonnes. After 2004, the catches started to decline (Bjørndal and Ekerhovd 2013) along with developments in stock size.

Between 2007 and 2010 the TAC for herring varied between approximately 1.2 million and 1.6 million tonnes; it was reduced to 988,000 tonnes in 2011. The blue whiting experienced a dramatic reduction in the TAC from 1.847 million tonnes in 2007 to 40,000 tonnes in 2011 (ICES Advice 2011, Book 9). This is due to a substantial reduction in stock size over time (Bjørndal and Ekerhovd 2013). For mackerel, on the other hand, the TAC has increased from 502,000 tonnes in 2007 to 959,000 tonnes in 2011. It must be noted that, while total catch of herring in most years is less than or equal to the TAC, the reverse is the situation for mackerel and blue whiting, with catches exceeding TACs.

Several countries participate in the fisheries in the Norwegian Sea, with Norway, Iceland and the United Kingdom (Scotland) as the most important ones. The overall TAC is distributed among the countries participating in the fishery, so that each country has a national TAC. As noted, there are currently no international agreements for mackerel. As a consequence, countries set unilateral TACs. A recent study show that the different fleets that operate in the Norwegian Sea have different cost structures and operate under different prices (Lappo 2013). 

Core research team:

Sturla Kvamsdal (researcher, SNF), project leader
Leif Sandal (professor, NHH)
Stein Ivar Steinshamn (professor, NHH)
Nils-Arne Ekerhovd (researcher, SNF)

Major publications:

  • Ekerhovd, N.-A. and S.F. Kvamsdal: Up the Ante on Bioeconomic Submodels of Marine Food Webs: A Data Assimilation-based Approach. Ecological Economics, 131, 250-261.
  • Ekerhovd, N.-A. and S.I. Steinshamn (2016): Economic benefits of multi-species management: The pelagic fisheries in the North-East Atlantic. Marine Resource Economics, 31(2), 193-210.
  • Kvamsdal, S.F. (2016): Technical Change as a Stochastic Trend in a Fisheries Model. Marine Resource Economics, 31(4), 403-419.
  • Kvamsdal, S.F., A. Eide, N.-A. Ekerhovd, K. Enberg, A. Gudmundsdottir, A.H. Hoel, K. Mills, F. Mueter, L. Ravn-Jonsen, L.K. Sandal, J.E. Stiansen, and N. Vestergaard (2016): Harvest Control Rules in Modern Fisheries Management. Elementa, 4, 114.
  • Kvamsdal, S.F., D. Poudel and L.K. Sandal (2016): Harvesting in a Fishery with Stochastic Growth and a Mean-Reverting Price. Environmental & Resource Economics 63(3), 643-663 (doi: 10.1007/s10640-014-9857-x)
  • Liu, X., M. Lindroos and L.K. Sandal (2016): Sharing a Fish Stock When Distribution and Harvest Costs are Density Dependent. Environmental & Resource Economics, 63(3), 665-686.
  • Kvamsdal, S.F. and L.K. Sandal (2015): The Ensemble Kalman Filter for Multidimensional Bioeconomic Models. Natural Resource Modeling 28(3), 321-347 (doi: 10.1111/nrm.12070).
  • Poudel, D., L.K. Sandal and S.F. Kvamsdal (2015): Stochastically Induced Critical Depensation and Risk of Stock Collapse. Marine Resource Economics 30(3), 297-313.


  • Kvamsdal, S.F., Maroto, J.M., Morán, M., Sandal, L.K. (2016). A bridge between continuous and discrete-time bioeconomic models: Seasonality in fisheries. Discussion Paper 20/16. Department of Business and Management Science.
  • Kvamsdal, S.F., Maroto, J.M., Morán, M., Sandal, L.K. (2016). A Bellman approach to periodic optimization problems. Discussion Paper 19/16. Department of Business and Management Science.
  • Kvamsdal, S.F. (2015). Indexing of Technical Change in Aggregated Data. SNF Working Paper 6/15.
  • Kvamsdal, S.F., L.K. Sandal (2014). The Ensemble Kalman Filter for Multidimensional Bioeconomic Models. SNF Working Paper 4/14.
  • Ekerhovd, N.-A., S.F. Kvamsdal (2014). Up the Ante on Bioeconomic Submodels of Marine Foodwebs. SNF Working Paper 13/14.

Lectures, conference & workshop presentations:

  • Sandal, L. (2016). Sustainability and Stochasticity in Ecosystem-Based Commercial Fisheries Management. RMA 2016.
  • Ekerhovd, N.-A. (2016). Economic benefits of multi-species management. IIFET 2016.
  • Kvamsdal, S.F. (2016). Indexing of Technical Change in Aggregated Data. Presentation, EAERE 2016.
  • Ekerhovd, N.-A. (2016). Economic benefits of multi-species management. Presentation, SNF 2016
  • Ekerhovd, N.-A. (2016). Up the Ante on Bioeconomic Submodels of Marine Foodwebs. Presentation, SNF 2016.
  • Kvamsdal, S.F. (2016). Harvest Control Rules in Modern Fisheries Management. Presentation. 17th Russian-Norwegian Symposium.
  • Kvamsdal, S.F. (2016). Up the Ante on Bioeconomic Submodels of Marine Foodwebs. Presentation, Stockholm Environmental and Resource Economics Seminar, Beijer Institute for Ecological Economics.
  • Kvamsdal, S.F. (2015). A Structural Model of Technical Change in a Fishery. SNF 2015.
  • Ekerhovd, N.-A. (2015). Up the Ante on Bioeconomic Submodels of Marine Foodwebs. Presentation, Resource Modeling Association Conference 2015.
  • Kvamsdal, S.F. (2015). A Structural Model of Technical Change in a Fishery. Presentation, EAERE 2015.
  • Kvamsdal, S.F. (2015). The Ensemble Kalman Filter. Presentation, Universidad Complutense de Madrid, NILS-seminar 2015.
  • Kvamsdal, S.F. (2015). EINSAM. Presentation, Havet og Kysten, Hurtigruten 2015.
  • Kvamsdal, S.F. (2014). Information Criteria for Ensemble and Particle Methods. Presentation, NHH Geilo seminar.
  • Kvamsdal, S.F. (2014). The Ensemble Kalman Filter. Lecture, NHH Norwegian School of Economics.
  • Kvamsdal, S.F. (2014). Up the Ante on Bioeconomic Submodels of Marine Foodwebs. Presentation, Bergen Energy & Environmental Economics Research Conference 2014.
  • Kvamsdal, S.F. (2014). Harvesting in a Fishery with Stochastic Growth and a Mean-Reverting Price. Presentation, IFORS 2014.
  • Kvamsdal, S.F. (2014). EINSAM. SNF Berlin seminar.
  • Kvamsdal, S.F. (2014). Data Assimilation for Marine Food Web Models. Presentation, WiMOpt2014.