Fig. 1. Schematic representation of modelling approaches distributed long axes of physical, biological and human complexity. The term complexity refers to the amount of detail incorporated in the model structure (reproduced from Plagányi Éva E et al. (2011) with permission from CSIRO Publishing).
Yellow spheres – RATS (Relegate All Top Species)
Orange spheres – MICE (Models of Intermediate Complexity for Ecosystem assessments)
Purple spheres – CATS (Complex Assess Tools)


Substantial advances have been made in the past decade in implementing an ecosystem approach to fisheries, but there remain gaps in the toolbox of approaches needed to address the complex science and management issues (Fig. 1).

These include methods for simultaneously assessing the status of both fisheries and other non-targeted species, including those of high conservation concern, and evaluating the trade-offs among management plans aimed at addressing conflicting objectives. There is a need for models of intermediate complexity that draw on the rigorous quantitative and statistical methodology of stock assessment approaches and extend this to representation of multiple co-existing species and stressors in an ecosystem.

Stakeholders increasingly expect ecosystem assessments as part of advice on fisheries management. Quantitative models to support fisheries decision-making may be either strategic (‘big-picture’, direction-setting, contextual) or tactical (focused on management actions on short time scales), with some strategic models informing the development of tactical models.

Fig. 2. Overview of a Models of Intermediate Complexity for Ecosystem assessments (MICE) examples illustrating the direct and indirect impacts of variable size-specific catches for tuna, sharks and billfish by commercial long-liners in the Coral Sea. Inter-connected components are (A) Ecological information, including multispecies trophic or competitive network and spatial habitat processes; (B) Environmental information, including physical and habitat drivers of ecological processes; (C) Human components of the system, including different fishing sectors and their behaviours, other stake-holders and economic drivers; (D) Anthropogenic effects, including fishing mortality; and (E) Management, including input and output controls as well as other environmental policies (from Plagányi et al. 2014).


“Models of Intermediate Complexity for Ecosystem assessments” (MICE) have a tactical focus, including use as ecosystem assessment tools. MICE are context- and question-driven and limit complexity by restricting the focus to those components of the ecosystem needed to address the main effects of the management question under consideration (Fig. 2).

Stakeholder participation and dialogue is an integral part of this process. MICE estimate parameters through fitting to data, use statistical diagnostic tools to evaluate model performance and account for a broad range of uncertainties. These models therefore address many of the impediments to greater use of ecosystem models in strategic and particularly tactical decision-making for marine resource management and conservation.

Mice are small, fast and smart and hence we use the term to represent “Models of Intermediate Complexity for Ecosystem assessments” (MICE), with these models having a tactical focus, including use as ecosystem assessment tools. MICE are context- and question-driven and limit complexity by restricting the focus to those components of the ecosystem needed to address the main effects of the management question under consideration.

They therefore have an intermediate level of complexity in representation of biological, physical and human components, compared with the CATS (Complex Assessment Tools) such as Atlantis who are good at strategic planning and RATS (Relegate All Top Species) (that stay down and avoid the top predators) that focus on lower trophic levels only. MICE focus on the sweet spot in the variance –complexity trade-off (Collie et al. 2014). MICE are also actively on the move with a growing number of examples being developed both within Australia and for other systems, including as part of the Belmont GULLS project focused on exploring adaptations to reduce vulnerability of marine-dependent coastal communities.


Making MICE social – SOPI

Consistent with the MICE philosophy of focusing on key interactions, we can extend these models into the human domain. We are developing this approach drawing on the social science Sense of Place concept (van Putten et al. 2018), which describes the emotions associated with a place. It is a combination of characteristics that makes a place special and unique. We have developed a conceptual framework for investigating how socio-psychological processes may influence ecosystem dynamics using a Sense of Place Index (SoPI) to capture feedback in a marine SES model. The psychological characteristics captured by the sense of place concept have important, practical implications for predicting the long-term dynamics of managed resources.

MICE on the Great Barrier Reef

MICE are being used to model the complex dynamics of Crown of Thorns Starfish (COTS) and coral interactions on the Great Barrier Reef, as a basis for supporting management strategies given COTS are a leading cause of coral decline, along with cyclones and bleaching. The Coral and COTS MICE has also been embedded in a network model (CoCoNet) to explore how connectivity between neighbouring reefs supports coral and COTS recruitment.

Whales and MICE

During the 1900s, many whales were commercially harvest almost to extinction. We used MICE to look at whale numbers from 1890 to now, and then coupled this with food availability and ocean physics, to understand how future changes to the ocean will influence their numbers (Tulloch et al. 2018; 2019).

Prawns and MICE

MICE are being applied to the Northern Prawn Fishery and related species to quantify the impacts on the ecosystem of different future freshwater flows that support estuarine and coastal fisheries and species of conservation concern. This research will inform on the likely water resource development alternatives and consequences across tropical Australian catchments (Kenyon et al. 2018).

MICE Application map


Contact: Dr. Eva Plaganyi