wp4: models to predict & test recovery strategies cefas: laurence kell & john pinnegar univ....
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WP4: WP4: Models to predict & test Models to predict & test recovery strategiesrecovery strategies
Cefas: Laurence Kell & John PinnegarCefas: Laurence Kell & John Pinnegar
Univ. Aberdeen: Tara Marshall & Bruce Univ. Aberdeen: Tara Marshall & Bruce McAdamMcAdam
ObjectivesObjectivesEvaluate alternative recovery strategies and identify the Evaluate alternative recovery strategies and identify the
relative value ofrelative value of– InformationInformation– ControlControl
Synthesise available models and data on key processes that Synthesise available models and data on key processes that may affect stock recovery in a common framework may affect stock recovery in a common framework
Use framework to evaluate alternative management strategies Use framework to evaluate alternative management strategies that are robust to uncertaintythat are robust to uncertainty
Quantify and compare the impacts of alternative management Quantify and compare the impacts of alternative management strategies in order to produce a suite of strategies to strategies in order to produce a suite of strategies to achieve stock rebuildingachieve stock rebuilding
1) Preparation of input data 1) Preparation of input data
2) Choice of performance criteria and 2) Choice of performance criteria and management objectivesmanagement objectives
3) Specify base-case scenario3) Specify base-case scenario
4) Perform evaluations4) Perform evaluations
TasksTasks
Starting state
of system
Performance Statistics used to evaluate performance of management procedures
against objectives
Operating Model represents the “true” dynamics of “ the biological system against which
performance will be measured
Observation Error Model generation of data on fishery and stock(s)
Management Procedure Assess status of stock and set
management options depending upon
perceived status of fishery stock(s)
Simulation
through time
Figure 1. Conceptual framework
From WP 5Alternative management strategies
Current Stock Status Future Stock Status
From WP 1,2,3Process modelsor alternative hypotheses
e.g. alternative assumptions about Natural mortalityMaturityRecruitmentDiscardsWeights at age
Model of data collection/samplingFeeds into WG Stock Assessment
Recovery? Yield of target/non-target stocks
FFramework for the ramework for the EEvaluation of valuation of MManagement anagement SStrategiestrategies
FEMSFEMS proposed and prototyped a generic framework known proposed and prototyped a generic framework known as as FLR FLR through a variety of contrasting case studiesthrough a variety of contrasting case studies
Why?Why?Despite constant efforts made to regulate fisheries fishing Despite constant efforts made to regulate fisheries fishing
capacity remains above that necessary to sustainable capacity remains above that necessary to sustainable exploit marine resources. exploit marine resources.
However, while the need to develop alternative management However, while the need to develop alternative management strategies is widely recognised it is almost impossible to strategies is widely recognised it is almost impossible to develop these by conducting large-scale experiments on develop these by conducting large-scale experiments on fish stocks. There has therefore been a trend towards the fish stocks. There has therefore been a trend towards the use of computer simulation to develop management use of computer simulation to develop management strategies that meet multiple, but often conflicting strategies that meet multiple, but often conflicting management objectives, and are robust to uncertainty management objectives, and are robust to uncertainty
FLRFLR is available from is available from http://www.flr-project.orghttp://www.flr-project.org
Process error:Process error: natural variability (in both time and space) in dynamic natural variability (in both time and space) in dynamic processes of the populations (e.g. recruitment, predation, growth and processes of the populations (e.g. recruitment, predation, growth and migration) and of the fisheriesmigration) and of the fisheries
Model error:Model error: related to the ability of model structure to capture the core of related to the ability of model structure to capture the core of the system dynamics, many models are assumption rich but data poorthe system dynamics, many models are assumption rich but data poor
Observation error:Observation error: related to collecting in-situ observations, such as total related to collecting in-situ observations, such as total catch, catch composition (e.g. length, age, sex), research survey indices, catch, catch composition (e.g. length, age, sex), research survey indices, efforteffort
Estimation error:Estimation error: related to estimating parameters of various models used related to estimating parameters of various models used in the assessment procedure, such as growth models, stock-recruitment in the assessment procedure, such as growth models, stock-recruitment models, virtual population analyses, statistical models models, virtual population analyses, statistical models
Implementation error:Implementation error: because management actions are never because management actions are never implemented perfectly and may result in realised total catch, catch implemented perfectly and may result in realised total catch, catch composition and effort that differ from those intended, e.g. misreporting.composition and effort that differ from those intended, e.g. misreporting.
UncertaintyUncertainty
Software Catalogue
Model Error?Model Error?
Relates to the ability of any one model structure to capture the core Relates to the ability of any one model structure to capture the core of the system dynamics, many models are assumption rich but data poor.of the system dynamics, many models are assumption rich but data poor.
FEMS was tasked by the European Commission with specifying FEMS was tasked by the European Commission with specifying
Cod and ClimateCod and ClimateHypotheses were that climate change acts Hypotheses were that climate change acts
throughthrough Growth, optimum temperature for growthGrowth, optimum temperature for growth Juvenile survivalJuvenile survival
oror Carrying capacityCarrying capacity
Therefore impacts onTherefore impacts onRecoveryRecoveryLong-term yieldsLong-term yieldsSustainable levelsSustainable levels
Management strategiesManagement strategies
Strategies investigated were either Strategies investigated were either those adopted by or under those adopted by or under consideration by the European consideration by the European CommissionCommission
Short-termShort-term– Recovery plans (30% increase in SSB)Recovery plans (30% increase in SSB)
Long-termLong-term– Harvest control rules (ensure F < FHarvest control rules (ensure F < FPA PA andand
SSB >SSB > BBPAPA))
Recovery PlansRecovery Plans
– This was because recovery in the This was because recovery in the short term depended upon conserving short term depended upon conserving fish that have already recruitedfish that have already recruited
Short-termShort-term– Despite contrasting climate Despite contrasting climate
change hypothesises, magnitude change hypothesises, magnitude of the change in temperature and of the change in temperature and the mechanism through which it the mechanism through which it acts (i.e. juvenile survival or acts (i.e. juvenile survival or carrying capacity), the predicted carrying capacity), the predicted recovery time was little affectedrecovery time was little affected
Recovery PlansRecovery Plans
– This was because recovery in the This was because recovery in the short term depended upon conserving short term depended upon conserving fish that have already recruitedfish that have already recruited
Short-termShort-term– Despite contrasting climate Despite contrasting climate
change hypothesises, magnitude change hypothesises, magnitude of the change in temperature and of the change in temperature and the mechanism through which it the mechanism through which it acts (i.e. juvenile survival or acts (i.e. juvenile survival or carrying capacity), the predicted carrying capacity), the predicted recovery time was little effectedrecovery time was little effected
– Recovery would be delayed however if bycatch Recovery would be delayed however if bycatch of cod in non-target fisheries was not controlledof cod in non-target fisheries was not controlled
Long-termLong-term
Scientific advice on safe biological limits to Scientific advice on safe biological limits to exploitation depends upon the correct exploitation depends upon the correct hypothesishypothesis
Reduced survival of recruits? Reduced survival of recruits?
Reduction in range?Reduction in range?
Since consequences areSince consequences are
↓↓FFlimlim if recruit survival reduced if recruit survival reduced
↓↓BBlimlim if range reduced if range reduced
However, the correct mechanism can only be However, the correct mechanism can only be detected through biological studies rather than detected through biological studies rather than through stock assessmentthrough stock assessment
North Sea FlatfishNorth Sea Flatfish100mm > 55100mm > 55°° 80mm < 5580mm < 55°°
Plaice in the NorthPlaice in the NorthSole in the SouthSole in the South
However, the distribution of However, the distribution of
plaice and sole varies wrt plaice and sole varies wrt
5555°°
North Sea FlatfishNorth Sea Flatfish100mm > 55100mm > 55°° 80mm < 5580mm < 55°°
Plaice in the NorthPlaice in the NorthSole in the SouthSole in the South
However, the distribution of However, the distribution of
plaice or sole may change plaice or sole may change
wrt 55wrt 55°°
0.2
0.3
0.4
0.5
1980 1985 1990 1995 2000 2005
Year
Wei
gh
t (K
g)
Plaice Age 4 Sole age 4
The productivity of plaice and The productivity of plaice and
sole has also changed sole has also changed
over timeover time
Cod and ClimateCod and ClimateHypotheses were that climate change acts Hypotheses were that climate change acts
throughthrough Growth, optimum temperature for growthGrowth, optimum temperature for growth Juvenile survivalJuvenile survival
oror Carrying capacityCarrying capacity
Therefore impacts onTherefore impacts onRecoveryRecoveryLong-term yieldsLong-term yieldsSustainable levelsSustainable levels
Management strategiesManagement strategies
Strategies investigated were either Strategies investigated were either those adopted by or under those adopted by or under consideration by the European consideration by the European CommissionCommission
Short-termShort-term– Recovery plans (30% increase in SSB)Recovery plans (30% increase in SSB)
Long-termLong-term– Harvest control rules (ensure F < FHarvest control rules (ensure F < FPA PA andand
SSB >SSB > BBPAPA))
Recovery PlansRecovery Plans
– This was because recovery in the This was because recovery in the short term depended upon conserving short term depended upon conserving fish that have already recruitedfish that have already recruited
Short-termShort-term– Despite contrasting climate Despite contrasting climate
change hypothesises, magnitude change hypothesises, magnitude of the change in temperature and of the change in temperature and the mechanism through which it the mechanism through which it acts (i.e. juvenile survival or acts (i.e. juvenile survival or carrying capacity), the predicted carrying capacity), the predicted recovery time was little affectedrecovery time was little affected
Recovery PlansRecovery Plans
– This was because recovery in the This was because recovery in the short term depended upon conserving short term depended upon conserving fish that have already recruitedfish that have already recruited
Short-termShort-term– Despite contrasting climate Despite contrasting climate
change hypothesises, magnitude change hypothesises, magnitude of the change in temperature and of the change in temperature and the mechanism through which it the mechanism through which it acts (i.e. juvenile survival or acts (i.e. juvenile survival or carrying capacity), the predicted carrying capacity), the predicted recovery time was little effectedrecovery time was little effected
– Recovery would be delayed however if bycatch Recovery would be delayed however if bycatch of cod in non-target fisheries was not controlledof cod in non-target fisheries was not controlled
Long-termLong-term
Scientific advice on safe biological limits to Scientific advice on safe biological limits to exploitation depends upon the correct exploitation depends upon the correct hypothesishypothesis
Reduced survival of recruits? Reduced survival of recruits?
Reduction in range?Reduction in range?
Since consequences areSince consequences are
↓↓FFlimlim if recruit survival reduced if recruit survival reduced
↓↓BBlimlim if range reduced if range reduced
However, the correct mechanism can only be However, the correct mechanism can only be detected through biological studies rather than detected through biological studies rather than through stock assessmentthrough stock assessment
North Sea FlatfishNorth Sea Flatfish100mm > 55100mm > 55°° 80mm < 5580mm < 55°°
Plaice in the NorthPlaice in the NorthSole in the SouthSole in the South
However, the distribution of However, the distribution of
plaice and sole varies wrt plaice and sole varies wrt
5555°°
North Sea FlatfishNorth Sea Flatfish100mm > 55100mm > 55°° 80mm < 5580mm < 55°°
Plaice in the NorthPlaice in the NorthSole in the SouthSole in the South
However, the distribution of However, the distribution of
plaice or sole may change plaice or sole may change
wrt 55wrt 55°°
0.2
0.3
0.4
0.5
1980 1985 1990 1995 2000 2005
Year
Wei
gh
t (K
g)
Plaice Age 4 Sole age 4
The productivity of plaice and The productivity of plaice and
sole has also changed sole has also changed
over timeover time