selecting model domains and boundaries in ecosystem
TRANSCRIPT
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Selecting model domains and boundaries in ecosystem modeling of the U.S. West Coast: process determines scale
Chris J. Harvey, Isaac C. Kaplan, and Phillip S. Levin
Northwest Fisheries Science CenterNOAA Fisheries, Seattle, WA USA
contact: [email protected]
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Overview
• Marine ecosystems on the U.S. West Coast
• Objectives of our research group
• How we delineated ecosystem “boundaries”
• Conclusions and future directions
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Dominant marine ecosystem:The California Current
Other major open coastal ecosystem: Southern California Bight
California Current
So. Cal. Bight
Major coastal/estuarine ecosystems: Puget Sound, Columbia River estuary, and San Francisco Bay
Puget Sound
Columbia River
San Francisco
Bay
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California Current
Our program’s research focus: The California Current
• This is where most of the federally managed fisheries occur (EEZ)
• Comparable to the spatial distribution of the targeted species
• Also where associated and potentially fragile communities are found
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California Current Ecosystem
• Main feature: California Current• South-flowing current• Shelf break to ~1000 km offshore• Surface to ~500 m deep• Numerous jets, eddies
• Coastal upwelling drives much of the area’s primary production
• Geological features• Narrow shelf• Capes, points• Submarine canyons and banks
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California Current Ecosystem
• Wide range of functional groups • Some highly sedentary• Some mobile within system• Some make long seasonal migrations, leave area entirely
• Human activities:• Fishing, mariculture• Shipping, transportation• Species introductions• Industrial activities• Dumping, dredging• Military use• Land use, eutrophication• Conservation actions
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Subject to large-scale seasonal fishing closures
Example: GroundfishConservation Areas, enacted since 2002; no bottom trawling
Darkblotched rockfish, Sebastes crameri
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Overview
• Marine ecosystems on the U.S. West Coast
• Objectives of our research group
• How we delineated ecosystem “boundaries”
• Conclusions and future directions
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California Current
Our goal: a spatially explicit ecosystem model to examine management alternatives
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Our goal: a spatially explicit ecosystem model to examine management alternatives
???
We wish to understand the role of (among other things):
• key “functional groups”• spatial and temporal closures• harvest strategies (e.g., ITQs)• environmental variability
…and to identify trade-offs, data gaps, and key hypotheses
Strategic and qualitative! (Not tactical and quantitative!)
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Proposed management
strategy
Ecosystem model
Initial system state
Subsequent system state
Management model
Monitoring
Apply decision rules
Implement decisions
Performancemeasures
New management
strategy
Iterative loop of management strategy evaluation
• We will interpret model outputs in a qualitative way• That, in turn, allows us more flexibility in, e.g., defining boundaries
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Overview
• Marine ecosystems on the U.S. West Coast
• Objectives of our research group
• How we delineated ecosystem “boundaries”
• Conclusions and future directions
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Latitudinal “boundaries”
Big Sur Coast
Cape Flattery
Columbia R., Astoria Canyon
Cape Blanco
Cape Mendocino
Monterey Bay, Monterey Canyon
Point Conception
Model domain
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Latitudinal “boundaries”
Heceta Bank?
Point Arena?
Model domain
Southern California/Mexico?
B.C.?
Did we leave out anything important?
Columbia Plume?
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ab
cd
efg
Depth“boundaries”
abcdefg0 m50
100150
550
1200
2400
200
7 layers; allows for some spatial detailbut limited by how narrow the shelf/slope is.
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abcdefg0 m50
100150
550
1200
2400
200
1200 m = seaward extent of bottom trawl survey200 m = approximate seaward extent of Groundfish Conservation Areas (GCAs)
150 m = approximate landward extent of GCAs
50 m = landward extent of bottom trawl survey
50 m = surface layer + nearshore communities
550 m = biodiversity break, slope groundfish
200 m = shelf break
Depth“boundaries”
Beyond 1280 m = no bottom contact gear
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abcdefg0 m50
100150
550
1200
2400
200
Depth“boundaries”
Did we leave out anything important?
• Some unique bathymetric features
• Islands• Seamounts• Canyons• High relief areas
• 20-m depth contour• Chlorophyll max• Upwelling• Kelp forests
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Data scaling: some key inputs are ~10 km x 10 km
Oceanographic fluxes(water, salinity,
temperature)Fishing effort
(bottom trawling)Benthic habitat types
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Biomass of Small Slope Rockfish in mg N/m3
(includes splitnose rockfish, aurora rockfish, longspinethornyhead)
Some sample output
Cape Mendocino
Cape Blanco
Columbia River
MontereyBay
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Overview
• Marine ecosystems on the U.S. West Coast
• Objectives of our research group
• How we delineated ecosystem “boundaries”
• Conclusions and future directions
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Our goal: a spatially explicit ecosystem model to examine management alternatives• Our questions are large scale, general, mainly concern fishing (e.g., “What is the effect of the GroundfishConservation Area?”)
• Underlying processes are also general
• Scale is quite coarse
• “Boundaries” are not very precise, but were based on:
• Oceanography, geomorphology
• Ecology
• Data availability
• For our purposes, imprecise boundaries are probably okay
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Our questions vs. all questionsData availability vs. accuracy
Complexity vs. practicalityModel domain
Ecology vs. managementData availability vs. accuracy
Depth of bathymetric contours
Detail vs. run timeQuestions vs. assumptionsCoastal scale vs. local scale
Number of polygons
Tradeoffs that we had to consider
Model variable Tradeoff(s)
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Topics we probably cannot study at this scale:
• Small MPAs
• Intertidal/estuarine questions (e.g., shellfish aquaculture)
• Local impacts (e.g., oil spills)
• The dynamics of the Columbia River plume
• Recovery strategies for most individual species