CodSize: Resolving impacts of Atlantic cod body size on population replenishment and coastal ecosystem change

About the project

CodSize aims to advance our knowledge on coastal ecosystem structure, as well as function and change. We will focus on the role of body size as a functional trait in a harvested coastal predator, the Atlantic cod.

We will take advantage of a no-take marine reserve centred around a fjord cod spawning area where fishing is not allowed.

First, we want to understand how spawning ecology and population replenishment is structured by body size diversity within a natural population. Resolving this question could have wide-ranging consequences for fisheries management, because most fisheries tend to remove the larger individuals and thereby cause severe size-truncation in harvested populations. We will combine novel technologies and data analyses for revealing spawning behaviour, habitat use and offspring production of individual fish in their natural environment. The latter will depend on successfully tracing cod offspring back to their parents in a natural fjord  environment. This will be a challenge, but recent methodological advances indicates that it can be achieved.

Our approach will include the use of advanced accelerometer tags and a large underwater telemetry array for measuring fish movements. This precision will open for novel applications of network theory, for instance by resolving how fish body size influence the mating system.

Second, we will combine data on feeding behaviour with individual trophic level of feeding to resolve how predator body size may shape how coastal ecosystems function.

Third, we will use empirical data to fill in models that utilise body size as the primary scaling factor of species interactions (ATN: allometric trophic network models) for predicting how the resilience and dynamics of coastal ecosystems may change in response to environmental change, including ocean warming.


Healthy cod stocks provide substantial ecosystem services to humans, most importantly as a source of food and employment but also for recreational fisheries where factors other than food provisioning determine angler satisfaction. Large predators like cod may also influence the capacity for coastal ecosystems function to mitigate climate change by storing carbon.

Understanding the role of predator body size as a functional trait, and adjusting management regulations accordingly, is therefore likely to benefit society by strengthening a number of ecosystem services.


The project owner is the Institute of Marine Research (IMR) and is funded by the Research Council of Norway (RCN).

RCN Project Number: 294926 (Project data bank at RCN) 

UiO Project Number: 190840



  • Albert Fernández-Chacón; David Villegas-Ríos; Even Moland; Marissa L. Baskett; Esben Moland Olsen & Stephanie M. Carlson (2020). Protected areas buffer against harvest selection and rebuild phenotypic complexity. Ecological Applications.  ISSN 1051-0761.  30
  • David Villegas-Ríos; Carla Freitas; Even Moland; Susanna Huneide Thorbjørnsen & Esben M. Olsen (2020). Inferring individual fate from aquatic acoustic telemetry data. Methods in Ecology and Evolution.  ISSN 2041-210X.  11, s 1186- 1198

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Published Jan. 5, 2021 12:04 PM - Last modified Feb. 2, 2021 10:03 AM