Bridging from single species tactical advice to ecosystem-
based strategic advice
Lesson 1: We should expect our models to fail, sometimes spectacularly so. But when we do we should take the opportunity to learn from the failure
Traditional approach to fisheries management
• Management approach focuses on F via catch & effort regulation
– Stock assessments recommend B and F reference points
– SSC recommend ABC (<=OFL) that includes scientific uncertainty –tactical advice
– Council recommend ACT (<=ABC) that includes management uncertainty (implementation uncertainty)
• Stakeholders limited to
– Commercial fishery interests
– Managers (protecting societal interest)
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Approach to incorporating scientific uncertainty
• Select %ile of probability distribution
• Lack of data in many systems means that P* is becoming ordinal as cFlim
But this assumes that all stakeholders will want a maximal F
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Stakeholders can be responsible
Council recommendation• 10M Lbs quota• 3 fish bag limit• >24 in min size
Stakeholder choice• 8M Lbs quota• 2 fish bag limit• >28 in min size
How and why did recreational anglers, CCA, and NGOs become
more conservative than managers?
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Stakeholder-centered approach
Stakeholders propose objectives, options and performance
measures
Revise options and performance measuresModel development
and modification Stakeholders
Review
model results
Recommendations
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Model Structure• Abundance
• Mortality
• Catch
N = Abundance F = Inst. Fishing mort. RateM = Natural mort. Z = Total mort.p = migration ratey = year s = seasona = age x = sexo = area f = fishery
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Parameter uncertainty
• Simulations drew from parameter distributions that reflected either– Scientific uncertainty– System uncertainty
• Recreational F – used 3 scenarios: either increasing, constant and decreasing scenarios with white noise variability (lognormal CV 10%)
• Ran multiple simulations to yield distributions of outcomes
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Recommended optionsSSB F Season closure
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Lesson 2
• Don’t under-estimate the ability of stakeholders to understand complicated management questions and processes.
• Stakeholder involvement is critical at all stages of management– Objectives– Management alternatives– Evaluation
EAM
Strategic advice: Management policies that support long term fishery and ecosystem sustainability
What kind of EAM do you want?
Lesson 3: Understanding of EAM by managers and stakeholders is at a infant’s level - education is critical
Case Study: Chesapeake Bay Fishery Ecosystem Plan
• Ecosystem boundaries– ~350 fishes described in Chesapeake Bay– Variation in life history causes boundary problems
FEP: Boundary issues
• Biological– 2 Large marine ecosystems
• Human– 11 states– 3 multi-jurisdictional commissions– 2 regional management councils– 2 nations
FEP: Simple strategic advice
• Patterns based on total removals• Empirical evidence
suggests ~250,000 mt may be sustainable
• 75,000 mt of non-menhaden harvest has been sustained
Ecosystem dynamics
• Used to examine ecosystem context of single species management decisions– What would happen if the region achieved a goal of a
10-fold increase in oyster biomass?• Concerns
• Fisheries model in a “microscopic” ecosystem• My species wasn’t included• Are we modeling the tail or the dog?
• Modeling effort was not integrated into management
• Maryland Sea Grant asked to facilitate an ecosystem based process for the Chesapeake Bay
Case study: Atlantic menhaden• Estuarine-dependent pelagic planktivore that provides
ecosystem-services – by filtering phytoplankton– important prey resource for charismatic piscivores
• Stock migrates along coast from Florida to Maine• Juveniles use estuarine nursery areas
• Stock assessment (2006) indicates neither stock is not overfished, nor experiencing overfishing.
• Yet concerns expressed over “localized” depletion in Chesapeake Bay
Localized depletion?
• A spatially-restricted decline in abundance that impairs ecological function– Predator production– Nutrient export
• Otolith chemistry evidence suggests spatial structure
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Lower Mid Upper Upper 7 Upper 9
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MS-models
• Predator-prey model– Climate-driven recruitments are strongly negatively
correlated – Stochastic, correlated SR function
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Lesson 3
• Defining the question is essential– What is localized depletion?
• Models with different outputs can’t be compared– What are the common metrics
• Reference points for non fishery endpoints are needed
Case study: Regime shifts in the northwest Atlantic
• Dramatic shift from a groundfish-dominated community to an elasmobranch-dominated community
• Multiple explanatory hypotheses
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Year
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mas
s in
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Gadids Flatfish Skates Other Dogfish
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120F
ish
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effo
rt (
103 d
)Groundfish & flounders Pelagic Elasmobranchs
Lesson 4:
• Even the most successful EM may not forecast the future state of the ecosystem– CBO budget forecasts have all been wrong, but
that doesn’t mean that they haven’t been useful.
• Managing expectation is critical
Recommendations• Given a goal, what approaches are feasible or useful?
– There needs to be a clear statement of what question is the model being used to ask
– Not all ecosystem questions require an EM• What comes first – goal or stakeholders?
– The stakeholders you have in the room will affect the stated goal or vision
– Engage stakeholders early and often• Strategic advice may not be of the form of control rules, e.g.,
ecosystem services– How then do EM feed into the management process,
particularly ?