An esteemed herring stock assessment model has been developed using Powersim Studio!
The Powersim Software team is proud to announce that the extensive research model on fish stock assessment, authored by Kristin Hamre (NIFES), Steinar Moen (Powersim) and Johannes Hamre (IMR) has accomplished a milestone. This research work has now resulted in publishing an article in the PeerJ Preprint Journal.
The project is based on a System Dynamics model created in Powersim Studio. The model includes thorough research work on Norwegian Spring-Spawning herring stock development. The assumptions in the model are based on an extensive collection of observed data, which not only validates the relationships within the model, but also gives the model good credibility in predicting results with 3-year simulations. Therefore, the model can offer better founded strategies for managing fisheries.
The project is a collaboration between scientists from NIFES and IMR, and Powersim Software, developed over the last 3 years by:
This model is based on a previous model studying the interactions between herring, capelin and cod in the Barents Sea, developed by Johannes Hamre and Steinar Moen and published in 2008. The current model uses a new growth equation and studies the herring species as an individual simulation. It may be used as a module in an ecosystem/multispecies simulations in the future.
The article presenting Hamre's work named "Systmod II: Approaching a real dynamic computer model for fish stock assessment and development of fishery strategies" was published in November 2016 in the PeerJ Preprints Journal.
Simulating development of fish stocks may be as complex as calculation of the development of the atmosphere, which is treated in meteorology as an initial value problem in physics. This approach was first proposed by Abbe and Bjerknes in the beginning of the 20th century and today huge systems of differential equations are used to predict the weather.
A similar approach to fisheries biology and ecology requires a real dynamic population model, which calculates the development of fish stocks from an initial state with equations that are independent of time. In Systmod II, we present a length-based growth function with a parameter for environmental variation and length-based data structure.
The model was validated for Norwegian Spring-Spawning herring, using observed data from ICES working groups, and correlations (R2) between simulated and observed stock were above 0.93.
The article is available for free and can be read in full length at: PeerJ Preprints Journal.
Below you can see the three contributors celebrating the publication with a famous Norwegian treat: "Lutefisk"; which is lye fish of cod with butter & bacon, mashed pies and potatoes.
From the left: Kristin Hamre, Steinar Moen and Johannes Hamre.