Development and parameterisation of a size-structured multispecies bioeconomic model integrating consumer demand

Marine fisheries provide a vital source of food and employment for a large portion of the world's population, underscoring the importance of sustainable exploitation methods. Traditional fisheries management often utilizes single-species models, which fail to consider ecological interactions and economic trade-offs, potentially resulting in overexploitation of stocks.

To tackle this issue, researchers have created a new size-structured, multispecies bioeconomic module that can be integrated into the OSMOSE ecosystem model, which represents exploited fish communities with size-dependent predator-prey interactions.

The bioeconomic model takes into account multiple species and size classes, allowing for size-dependent market prices for fish. Fishing costs and profits are modeled using a modified version of the Gordon-Schaefer model, which now applies to multiple interacting species. Consumer demand is represented through a nested Dixit-Stiglitz utility function with three levels of constant elasticity of substitution, considering fish commodity, species, and size classes.

For the model's parameters, the researchers developed a method to estimate them when empirical data is not available. This method was tested on a North Sea OSMOSE configuration, which includes 15 different species. The estimation process successfully determined the six bioeconomic parameters needed to operate the model. The findings suggest that cost parameters primarily correlate with species biomass variability rather than fishing gear type, while fish prices are more influenced by consumer demand than by fish availability.

This novel framework offers a foundation for evaluating the economic implications of various climate change scenarios and promoting sustainable fisheries management.