“BOOM OR BUST”: RESTORING BAY SCALLOP POPULATIONS THROUGH

THE RELEASE OF COMPETENT LARVAE. ARE CONTAINMENT

BOOMS NECESSARY?

Jay R. Leverone Stephen P. Geiger, William S. Arnold, and Jaime

Greenawalt

Bay Scallop Larval Release Bay Scallop Larval Release Restoration Projects in FloridaRestoration Projects in Floridasince 2003 ( Larval Release Locations)since 2003 ( Larval Release Locations)

North Pine Island Sound

South Pine Island Sound

History of Bay Scallopsin Pine Island Sound

• Bay scallops were commercially harvested in Lee County until 1963

• Two major construction projects occurred during the 1960’s

• Recreational fishery persisted until 1990• FWRI continues to monitor bay scallop

populations in northern Pine Island Sound• First restoration occurred in 2003• Second restoration in 2005-06

Pine Island Sound Project Rationale

• North Pine Island Sound is less impacted than South Pine Island Sound

• Bay scallops are still found in North PIS, although in very low numbers

• Suitable habitat is available in both locations

• Larval release strategy offers a more cost-effective and less labor intense approach than previously attempted restoration efforts

Methods

• Spawn scallops in hatchery and raise larvae under optimal conditions

• Release pediveligers into containment booms” or free-release

• Monitor settlement, juvenile and adult population densities at release site

= North Pine Island Sound stations (1995 – present)

= South Pine Island Sound stations (2004 – present)

ANNUAL BAY SCALLOP ABUNDANCE, PINE ISLAND SOUND, FL. TOTAL NUMBER OF SCALLOPS. (FWRI).

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006North PIS 49 15 46 47 52 56 110 13 28 ? ? ?

South PIS --- --- --- --- --- --- --- --- --- ? ? ?

Demere Key

Powerlines

FWS Refuge

Pineland

Pine Island Sound Larval Release Sites (2003 – 2005)

Replicate 1 2 3 Control Outside1 6 1 0 0 02 2 2 0 0 03 3 2 3 0 04 1 3 1 0 05 0 1 (lost) 0 0

Total 12 9 4 0 0

NUMBER OF SCALLOP POSTLARVAE ON SPAT COLLECTORS (2003)

Treatment

2003 Scallop DistributionTotal = 28; Density = 1.4

2004 Scallop DistributionTotal = 21; Density = 1.05

Restoration SiteTotal = 63; Density = 160

2005 Scallop DistributionTotal = 1,868; Density = 93.4

2006 Scallop DistributionTotal = 163; Density = 8.15

2005 Scallop DistributionTotal = 48; Density = 2.4

Demere Key

Powerlines

FWS Refuge

Pineland

Pine Island Sound Larval Release Sites (2005)

NUMBER OF POSTLARVAE (=SPAT) PER COLLECTOR (FALL, 2005)

  Demere Key Power Lines Pineland FWS Refuge

Replicate Outside

Inside

Outside

Inside

Outside

Inside

Outside

Inside

1 1 36 1 6 0 10 2 3

2 0 22 1 18 0 31 2 3

3 1 8 0 41 0 3 3 4

4 1 36 0 22 1 6 4 3

5 --- 45 2 49 0 27 2 1

6 --- 53 --- --- --- --- --- ---

Mean 0.8 33.3 0.8 27.2 0.2 15.4 2.6 2.8

2006 Free-Release Sites

Site 1

Site 2

Site 3

Site 4

Settlement of Postlarvae on Collectors: Free-Release (2006)

Site 1 Site 2 Site 3 Site 4East 0 1 0 3

South 0 1 0 0West 0 --- 0 0North 0 --- 0 3

TOTAL 0 2 0 6

Deployed: 6/1/06 Retrieved: 7/13/06

ANNUAL BAY SCALLOP ABUNDANCE, PINE ISLAND SOUND, FL. TOTAL

NUMBER OF SCALLOPS. (FWRI, 2005).

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006North PIS 49 15 46 47 52 56 110 13 28 21 1,868 163South PIS --- --- --- --- --- --- --- --- --- 1 48 26

Conclusions

• Bay scallop abundance and dispersion in PIS has increased since restoration began in 2003

• Releasing pediveliger larvae is a viable strategy for restoring bay scallop populations

• “Booms” are helpful for assessing recruitment

• Knowledge of local circulation should obviate the need for booms

CHALLENGES AHEAD

• Development of an appropriate marker (e.g., genetic tag) to provide a definitive link (“smoking gun”) between broodstock, released larvae, recruits and adult scallop populations

• Understanding and (hopefully) mitigating red tide effects on all bay scallop life stages; refine restoration techniques accordingly

FUNDING

•Charlotte Harbor National Estuary Program•Ocean Trust Foundation•South Florida Water Management District•Mote Scientific Foundation