4  Overview of Example Objects

openMSE includes a number of built-in objects that can be used for testing and demonstration. These objects span all four subcomponent types, Stock, Fleet, Obs, and Imp, along with a set of example OM objects that combine them in configurations of increasing complexity.

The objects are intended for demonstration and testing purposes only. The biological and exploitation values should not be interpreted as representing real stock assessments or used to inform management advice.

Chapter 12 walks through how each object is constructed step by step.

4.1 Stock Objects

Three example Stock objects are provided, representing species with contrasting life histories and model configurations. See Section 12.1 for full construction details.

Object	Common name	Key characteristics
AlbacoreExStock	Albacore tuna	Long-lived, slow-growing, low \(M\), low recruitment variability, 2-area
ButterfishExStock	Butterfish	Short-lived, fast-growing, high \(M\), high recruitment variability, 2-area
SeasonalSpatialExStock	Reef fish	Short-lived, monthly time steps, seasonal recruitment pulse, 3-area ontogenetic movement

4.2 Fleet Objects

Two example Fleet objects are provided, representing gear types with contrasting selectivity patterns. See Section 12.2 for full construction details.

Object	Selectivity type	Key characteristics
AsympExFleet	Asymptotic	Logistic selectivity pattern; effort builds gradually to a plateau
DomeExFleet	Dome-shaped	Reduced selectivity at largest sizes; slower effort build-up

4.3 Obs Objects

Five example Obs objects are provided, representing monitoring programs of increasing data richness. See Section 12.3 for full construction details.

Object	Data types
CommercialFleetObs	Landings, discards, effort, CPUE
CatchAndSurveyObs	Landings, survey index
AgeStructuredObs	Landings, discards, survey index, age compositions (landings and discards)
LengthStructuredObs	Landings, discards, survey index, length compositions (landings and discards)
DataRichObs	Landings, discards, effort, CPUE, survey index, age and length compositions (landings and discards)

4.4 Imp Objects

Four example Imp objects are provided, representing different assumptions about how management advice is realised in practice. See Section 12.4 for full construction details.

Object	Key characteristics
FullComplianceImp	Perfect compliance: TAC and effort advice realised exactly (Mean = 1, SD = 0); 100% immediate uptake of size regulations.
OverageImp	TAC and effort consistently realised 5-25% above advice, with added simulation-to-simulation and year-to-year stochastic variation.
UnderageImp	TAC and effort consistently realised 10-30% below advice, with added simulation-to-simulation and year-to-year stochastic variation.
PartialSizeComplianceImp	Perfect TAC and effort implementation, but only 60% of the fleet adopts a newly-advised size regulation in the year it changes.

4.5 OM Objects

Five pre-assembled OM objects combine the example stocks, fleets, and observation programs in configurations of increasing complexity. See Section 12.5 for full construction details.

Object	Stocks	Fleets per stock	Obs program(s)	Notes
SingleStockOM	AlbacoreExStock	AsympExFleet	AgeStructuredObs
TwoFleetOM	AlbacoreExStock	AsympExFleet, DomeExFleet	AgeStructuredObs, CatchAndSurveyObs
MultiStockOM	AlbacoreExStock, ButterfishExStock	AsympExFleet, DomeExFleet	Albacore: AgeStructuredObs, CommercialFleetObs; Butterfish: CatchAndSurveyObs, LengthStructuredObs
ComplexOM	AlbacoreExStock, ButterfishExStock (complex)	AsympExFleet	AgeStructuredObs	Stock complex
SeasonalSpatialOM	SeasonalSpatialExStock	DomeExFleet	CommercialFleetObs	Monthly seasons, 3-area spatial model

ComplexOM groups both stocks into a single stock complex (StockComplex), meaning fishery data and management advice are handled at the complex level. See Chapter 20 for more details on stock complexes.

SeasonalSpatialOM uses Seasons = 12 to match the monthly age structure of SeasonalSpatialExStock. It is an example OM with sub-annual time steps and a multi-area ontogenetic spatial model.