International Conference on Shellfish Restoration 2006 - Charleston, SC

Oyster Reef Restoration Using “Spat Seeding”: Early Reef Development and Performance at Sites

in New Hampshire, USA

http://oyster.unh.edu

Ray Grizzle, Jennifer Greene, and Mark Capone

Current Status of the Eastern Oyster, Crassostrea virginica

(P. Trowbridge)

• Extreme population declines in many areas from disease (MSX, Dermo), predators, over-harvesting, pollution, habitat degradation

• New Hampshire Estuaries Project goals: 20 restored acres, and 50,000 bushels standing stock by 2010

Nova Scotia

Maine

Cape Cod

Great Bay

A ‘pristine’ NH oyster reef

• few dead shells

• many live oysters (500/m2 in some areas)• extensive vertical structure in some areas

Badly Degraded Reef Reef With Some ‘Structure’

• mostly dead shells• sparse live oysters (~20/m2)• minimal vertical structure

• few dead shells• many live oysters (~100/m2)• some vertical structure• excessive sedimentation

How do we restore oyster reefs?

1. Identify potential causes for population declines on site-by-site basis

2. Design site-specific construction/restoration protocol

3. Assess initial construction/restoration

4. Maintain “restored” area

5. Assess long-term development and performance

Life Cycle of the Eastern Oyster, Crassostrea virginica

Trochophore LarvaVeliger Larva

Straight-hinge stage

Juvenile/SpatAdult

Egg

Oyster Life Cycle

Sessile, Benthic

Oyster Restoration = Facilitating the Life Cycle

Remote Setting, Early Grow-out (Nursery), & Reef Construction

Shellfish Restoration Sites, Dates of Construction:

• Salmon Falls River, 2000

• South Mill Pond, 2001

• Adams Point, 2003

• Nannie Island, 2004

• Bellamy River, 2005, 2006

Salmon FallsRiver

BellamyRiver

AdamsPoint

NannieIsland

South MillPond

Adams Point – An Experimental Scale Adams Point – An Experimental Scale Restoration ProjectRestoration Project

•Experimental design (2 x 2 factorial) to test: 1) two cultch types, and 2) two spat seeding densities

•Each treatment replicated 3 times 12 mini-reefs (2m x 3m) constructed

•Mini-reef bases built up to ~30 cm height with crushed granite

•Spat-on-cultch (shell or rock) spread over surface of granite bases

Adams Point-Experimental DesignAdams Point-Experimental Design

How many spat should be expected from the remote setting process?

• Spat setting success has ranged from <5% to >50% in our trials

• Important factors:

cultch

food

water quality

condition of the larvae

We can’t believe they all died!We can’t believe they all died!

Nursery Raft Survival and Growth

• ~75% survival is typical for 6 – 8 weeks on nursery raft

• Growth typically averages 2 - 3 mm/week

• Some animals ~1 mm/day

Development of Constructed Mini-Reefs

Adams Point, 2003-2006

• Consistent density decline

• Similar (but elevated compared to natural reef) densities after ~3 years post-construction

• Some originally seeded oysters in 2nd year of maturity

• Substantial development of vertical structure…

Performance of Constructed Mini-Reefs

Adams Point, Summer 2006

• Maximum ~6% water filtration (seston removal) after 3.2 years

Two New Programs: Oyster Conservationists and Shell RecyclingDo you want to participate in oyster restoration in New Hampshire?

http://oyster.unh.edu

Acres

Site/Construction Year(s) Larvae Source/Experimental Test Restored Current Status

Salmon Falls River/2000 XBreed larvae vs. native transplant 0.1 ~100% mortality

South Mill Pond/2001 ME larvae; oysters with blue mussels <0.1 ~100% mortality

Adams Point/2003 ME larvae; low vs. high density 0.05 >50% mortality

Nannie Island/2004 ME larvae; large vs. small reefs 1.25 >50% mortality

Bellamy River/2005 NH larvae; multiple mini-reefs 1.5 >50% mortality

2006 NH larvae; multiple mini-reefs 1.5 ?

TOTAL: 4.4 acres

Summary of New Hampshire Shellfish Restoration Projects

ACKNOWLEDGMENTS• UNH: Ryan McDonnell, Kaitlin Graiff, Dave Shay, Deb UNH: Ryan McDonnell, Kaitlin Graiff, Dave Shay, Deb

Lamson, Ben Winslow, Sarah Mikulak, Michelle GraffamLamson, Ben Winslow, Sarah Mikulak, Michelle Graffam

• Interns: William Walker, Winnie Wong, Sarah Morrison, Interns: William Walker, Winnie Wong, Sarah Morrison, Alicia June, Blake BowickAlicia June, Blake Bowick

• Oyster Conservationist Volunteers, Active Shell RecyclersOyster Conservationist Volunteers, Active Shell Recyclers

• Toni Simmons/Muscongus Bay AquacultureToni Simmons/Muscongus Bay Aquaculture

• Davis FoundationDavis Foundation