Overview of OSMOSE

Model name: OSMOSE

MEECE Area of implementation:

Model description:

OSMOSE is a multispecies and Individual-based model (IBM) which focuses on fish species. This model assumes opportunistic predation based on spatial co-occurrence and size adequacy between a predator and its prey (size-based opportunistic predation). It represents fish individuals grouped into schools, which are characterized by their size, weight, age, taxonomy and geographical location (2D model), and which undergo major processes of fish life cycle (growth, explicit predation, natural and starvation mortalities, reproduction and migration) and a fishing mortality distinct for each species (Shin and Cury 2001, 2004). OSMOSE, uncoupled version, has been first applied to the Benguela upwelling ecosystem for which 12 fish species have been specified, from small pelagic fish to large demersal species (Shin et al. 2004, Travers et al. 2006). The model needs basic parameters that are often available for a wide range of species, and which can be found in FishBase for instance.

In output, a variety of size-based and species-based ecological indicators can be simulated and converted to in situ data (surveys and catch data) at different levels of aggregation: at the species level (mean size, mean size-at-age, max size, trophic level etc), and at the community level (slope and intercept of size spectrum, Shannon diversity index etc). The model can be calibrated to observe biomass, using genetic algorithms.

The coupling process used to link OSMOSE to LTL models (NPZD, BFM) models is the predation process (Travers et al.) The LTL model is used as a prey field for the HTL model (concentration of nitrogen/carbon concentrations, converted into wet biomass) and the HTL model provides a predation mortality field for the LTL model. In a second step, other processes linked to detritus or nutrient boxes will be explicitly modelled for the coupling (egestion, excretion, natural mortality).

Different scenarios have been run, including the simulations of Marine Protected Areas (Yemane et al. 2009, Shin et al. 2001b), fishing moratoriums (Marzloff et al. 2009), overexploitation scenarios (Shin et al. 2004, Travers et al. accepted), combined effects of climate change and overexploitation.

Downloads:
OSMOSE Description as pdf
OSMOSE Manual (Feb 2010)