There are many alternative ways to condition Operating Models which we use to represent resource dynamics

The most common way is to use an Integrated Stock Assessment like SS or Multifan-CL, or a spatial model conditioned on fisheries data.

• This implies that the assessment is able to describe nature almost perfectly
• If this is true why bother with MSE?

Basing an OM on the current assessment model has arguably the lowest demands for knowledge and data and allows the tRFMOs to make a phased transition from the stock assessment paradigm to a risk based approach.

If a management procedure can not perform well when reality is as simple as implied by an assessment model it is unlikely to perform adequately for more realistic representations of uncertainty about resource dynamics.

Feedback is an important element of control systems, i.e. to ensure that monitored signals and inputs do not exceed pre-specified levels.

The ability to control a system depends on uncertainty about the system and measurement errors.

Control systems can be

• white box where one has full knowledge of a system, e.g, traditional stock assessment
• grey box e.g. a biomass dynamics model with a production function based on only a few parameters is used; or a
• black box the control is based on data alone, e.g. an empirical harvest control rule

Stock assessment mainly assumes density dependence in stock recruitment relationship, but many recent studies have shown that parental biomass is a poor predictor of recruitment

To model uncertainty the tRFMOs run an uncertainty grid

• Steepness
• Natural Mortality
• Selection Pattern
• Data Weighting
• Growth
• …

Scenarios 4800, from raw data-> conversion of size to age-> Growth-> M-> selection->SRR->reference points->projection

Scenarios 4800, from raw data-> conversion of size to age-> Growth-> M-> selection->SRR->reference points->projection