Spatial Bioeconomic Model Evaluations of Round 1 Draft MPA Arrays/Proposals

Dr. Christopher Costello, MLPA Master Plan Science Advisory Team andUniversity of California, Santa Barbara

Dr. Will White, University of California, Davis

Presentation to the MLPA Master Plan Science Advisory TeamApril 1, 2009 • Los Angeles, CA

Marine Life Protection Act Initiative

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Model Inputs

• Geographic– Habitat maps– Proposed marine protected area (MPA) boundaries

and regulations• Species-specific

– Life history (growth, natural mortality, fecundity)– Adult movement (home range diameter)– Larval dispersal (pelagic larval duration, spawning

season, some behavior)– Dispersal patterns from UC Los Angeles / UC Santa

Barbara circulation model– Egg-recruit or settler-recruit relationship (critical to

population persistence)

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Model Inputs

• Two models: UC Davis and UC Santa Barbara– Structurally similar, but slightly different

approaches to modeling adult movement, overall level of fishing, other details

– Concordance in results inspire confidence that outcomes not sensitive to details of any one model

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Model Inputs

• Updates– Oceanography

• Dispersal matrix is species specific. Parameterized over range of oceanographic conditions (1996-2002)

– Fishing fleet model• Fleet model – responds to spatial abundance of fish• Data compiled by Ecotrust, parameterization of fleet

model is underway (distance, congestion, weather, etc.)– Validation

• Preliminary model outputs evaluated by fish experts• Now incorporate north-south gradient in species

abundance

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Model Inputs: Species

• Ocean whitefish• Black surfperch• Opaleye• Kelp bass• Kelp rockfish• Sheephead• Red sea urchin• California halibut

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Model Outputs

• Conservation– Spatial distribution of larval settlement and

biomass– Total settlement and biomass (summed over

study region, weighted sum across species)• Economic

– Spatial distribution of yield– Total yield and profit (summed over study

region, weighted sum across species)

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Model Outputs

• Other Data– Spatial distribution of fishing effort– Larval connectivity patterns

• All outputs are based on long-term equilibria• Each output is calculated for a range of

assumptions about future fishery management outside MPAs1

1For complete list of assumptions, see evaluation methods document, Chapter 8, Appendix C.

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Model Results

Spatial Distribution of Larval Settlement

Model: UC Davis

Species: Ocean Whitefish

Assumption: MSY Management

*Also run for “unsuccessful” and “conservative” management

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Model Results

Spatial Distribution of Biomass

Model: UC Davis

Species: Ocean Whitefish

Assumption: MSY Management

*Also run for “unsuccessful” and “conservative” management

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Model Results

Spatial Distribution of Fishing Effort

Model: UC Santa Barbara

Species: Red Sea Urchin

Assumption: MSY Management

*Also run for “unsuccessful” and “conservative” management

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Model Results

Spatial Distribution of Fishery Yield

Model: UC Santa Barbara

Species: Red Sea Urchin

Assumption: MSY Management

*Also run for “unsuccessful” and “conservative” management

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Model Results

Region-by-Region Biomass (MSY management, UC Davis model)

0.480.520.490.450.48External COcean Whitefish

0.390.500.450.420.43External BOcean Whitefish

0.390.500.450.420.42External AOcean Whitefish

0.370.490.430.410.41Existing MPAsOcean Whitefish

South Islands

North Islands

North Mainland

South Mainland

TotalMPA Array orProposal

Species

Regions:• Southern mainland: Mexico to Long Beach • Northern mainland: Long Beach to Point Conception • Northern Channel Islands: San Miguel, Santa Rosa, Santa Cruz

and Anacapa• Southern Channel Islands: San Nicolas, Santa Barbara, Santa

Catalina, San Clemente

Range: 0 (no biomass) to 1 (maximum unfished biomass)

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Model Results

Region-by-Region Yield (MSY management, UC Davis model)

0.771.320.961.170.91External COcean Whitefish

0.961.060.991.030.99External BOcean Whitefish

0.971.050.981.030.98External AOcean Whitefish

1.001.001.001.001.00Existing MPAsOcean Whitefish

South Islands

North Islands

North Mainland

South Mainland

TotalMPA Array orProposal

Species

Note: Some regions see improvement in yield over existing MPAsRegions:• Southern mainland: Mexico to Long Beach • Northern mainland: Long Beach to Conception • Northern Channel Islands: San Miguel, Santa Rosa, Santa Cruz

and Anacapa• Southern Channel Islands: San Nicolas, Santa Barbara, Santa

Catalina, San Clemente

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Model Results

MPA-by-MPA Biomass (MSY management)Biomass (UCSB Model)

00.0050.010.0150.020.0250.03

Sout

h_Sa

n_Di

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Bay_

SMCA

UCSB

_SMR

Malib

u_Ea

st_S

MR

Big_

Syca

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_SMR

Portu

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MCA

Lagu

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_SMR

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ank_

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ock

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MPA Name

Bio

mas

s (%

of u

nfis

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Model Results

MPA-by-MPA Self-Recruitment & Persistence (MSY management)

0.060.00HalibutSanta Catalina Island

0.180.08Red Sea UrchinSanta Catalina Island

0.200.05SheepheadSanta Catalina Island

0.190.06Kelp RockfishSanta Catalina Island

0.230.06Kelp BassSanta Catalina Island

0.320.07OpaleyeSanta Catalina Island

2.601.00Black SurfperchSanta Catalina Island

0.250.11Ocean WhitefishSanta Catalina Island

Self persistence (UCD)Self recruitment (UCD)SpeciesMPA name

Self recruitment: Fraction of settling larvae that were produced locally (Range 0 -1) • Measure of isolation, connectedness (0 = totally isolated)

Self persistence: Measure of whether MPA is self-sufficient • Values less than or equal to 1 are dependent on larvae from elsewhere.• Values greater than 1 are self-sufficient.

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Model Results: Proposal Rank

Ranking for conservationvalue (nearly) preservedacross models and fishingscenarios

Unsuccessful Management

00.050.10.150.20.250.30.35

ExtC

TopA

Opa

lB

LapB

ExtB

TopB

LapA

Opa

lA

ExtA

Exis

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MPA Array

Con

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ExtC

TopA

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ExtB

TopB

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Opa

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ExtA

Exis

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MPA Array

MSY Fishing Scenario

0.50.520.540.560.580.60.620.64

Con

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UCD Model Results: BiomassConservation Value

Total biomass (relative to unfished)

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UCD Model Results: Fishery YieldConservation Value

Total biomass (relative to unfished)

Economic Value

Total yield (relative to MSY)

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UCD Model Results: Biomass x YieldConservation Value

Total biomass (relative to unfished)

Economic Value

Total yield (relative to MSY)

Total biomass(relative to unfished)

Tota

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UCSB Model Results: Biomass x YieldConservation Value

Total biomass (relative to unfished)

Economic Value

Total yield (relative to MSY)

Total biomass(relative to unfished)

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Conclusions

• Models are running smoothly – output available to assist in modifying arrays and proposals

• Ranking of MPA arrays and proposals for conservation value is insensitive to (1) model and (2) assumption about fishery management outside

• Differences in fishery management outside MPAs have strong effect on model results. But given similar placement, larger MPAs lead to higher conservation value.

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