priority living resource areas

Priority Living Resource Areas

Using GIS and Expert Judgment to Identify Target Species “Hot

Spots”

John Wolf and Mike FritzChesapeake Bay Program Office

May 22, 2007

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Habitat Requirements for Chesapeake Bay Living Resources

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Species Selection

• From HR2Fish Shellfish

• Added species for which “new” potential habitat information existed

• SAV handled separately

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Species Considered

• Menhaden• Striped Bass• Anchovy• Alewife• Hickory Shad• American Shad• Yellow Perch• White Perch• Blueback Herring• Largemouth Bass*• Chain Pickerel*

• Blue Crab• Oyster• Soft Shell Clam• Hard Shell Clam• Spot• Speckled Sea Trout• Postlarvel Blue Crab*• Catfish*• Summer Flounder*• Atlantic Sturgeon*• Croaker*

* species or layers not included in HR2

Water Column Bottom

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Assumptions

• For species with potential habitat distribution maps for multiple life stages, composite maps were produced by combing individual GIS layers

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Assumptions (cont.)

• Water Column and Bottom Species initially kept separate

• Each species treated equally (no weighting)

• SAV treated separately

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SPECIES LIFESTAGE MONTHS SALINITYLargemouth Bass

Adult Spring <3pptAdult Summer <3ppt

Chain PickerelAdult Spring <3pptAdult Summer <3ppt

Catfish2 (channel, white, brown bullhead, yellow bullhead)

Adult Spring 15ppt (max. of the 4 spp)Adult Summer 15ppt (max. of the 4 spp)

Atlantic Sturgeon3

Larvae Spring 0-2.2pptJuvenile Spring & Summer 3-16ppt

Summer Flounder4

Juvenile (YOY) Spring & Summer 0-37Adult Summer 0-37

Atlantic CroakerJuvenile Spring 50-15ppt suitable; <24ppt

unsuitableJuvenile Summer 56-26ppt suitable; <1ppt

unsuitable

2Catfish Populations in the Chesapeake Bay. January 1998. CBP.3Fishery Management Plan for Atlantic Sturgeon. Nov. 1990. ASMFC.4Chesapeake Bay Summer Flounder FMP. 1991. CBP.5Habitat Suitibility Index Models: Juvenile Atlantic Croaker. June 1985. USFWS.

Non-HR2 Species Decision Rules

Based on interpolated spring and summer salinity 1985-1997

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Non-HR2 Species Decision Rules

Based on affinity for eelgrass beds – SAV Tier II within historic extent of eelgrass (VIMS)• Postlarval blue crab• Juvenile speckled sea trout

Potential Oyster Habitat• Yates for MD (CBL)

• Baylor for VA (VMRC)• Private Oyster Leases for VA (VMRC)

• Oyster Sanctuaries (MD)

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GIS Process

1. Digital boundaries of habitats2. Combine multiple life stage maps into

single species map3. For (a) water column and (b) bottom

species, overlay each of the 11 species maps

4. Identify number of target species occupying the same habitat areas

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Co-occurrence of Bottom Species

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Co-occurrence of Water Column Species

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GIS Process

1. Digital boundaries of habitats

2. Combine multiple life stage maps into single species map

3. For (a) water column and (b) bottom species, overlay each of the 11 species maps

4. Identify number of target species occupying the same habitat areas

5. Team members look for clusters that reflected natural “break points”

6. Establish “high priority” and “medium priority” ranges based on number of species

7. Combine water column and bottom species to produce draft PLRA’s

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Draft Priority Living Resource Areas

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* These layers were NOT combined with the fish and shellfish layers because they were based on different data and used at different spatial scales.They were compared visually with PLRA’s. All SAV areas overlapped

except for four small tributaries

SAV Process

1. Developed by SAV Workgroup2. Examined …

- changes in SAV cover from 1992-1997 using VIMS aerial survey data, and

- SAV status as percentage of Tier II are in 1997 by CBP segments

3. Priority SAV* areas were …- segments that lost over 60 hectares of SAV from 1992

to 1997- segments that had no mapped SAV in 1997

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Priority SAV Areas were those that lost over 60 HA of SAV from 1992 to 1997

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Segments with No SAV Mapped in 1997

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Final Priority Living Resource Areas

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Monitoring Segments with PLRA’s