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North CapeNorth Cape Scallop Restoration ProjectScallop Restoration Project
Lessons learned from the restoration efforts in Lessons learned from the restoration efforts in Rhode Island’s south county salt pondsRhode Island’s south county salt ponds
Boze Hancock1, James Turek2, Najih Lazar3, and John Catena4
1Coordinator, North Cape Shellfish Restoration Program, Narragansett, RI2NOAA Restoration Center, Narragansett, RI
3RIDEM Division of Fish and Wildlife, Jamestown, RI4NOAA Restoration Center, Gloucester, MA
Grounding of the North Cape, January 1996
828,000 Gallons of No. 2 Fuel Oil Released to Block Island Sound
‘‘North Cape’ RestorationNorth Cape’ Restoration
Damages settlement in 2000Damages settlement in 2000
Shellfish Restoration one of several programsShellfish Restoration one of several programsto compensate for 150 million lost bivalvesto compensate for 150 million lost bivalves
Shellfish Restoration program began in 2002Shellfish Restoration program began in 2002Coordinator (Karin Tammi, 2002-2003; Coordinator (Karin Tammi, 2002-2003;
Boze Hancock,2004 – present) Boze Hancock,2004 – present)Assistant & 4 to 6 staff and students annuallyAssistant & 4 to 6 staff and students annually
Project completion expected 2007Project completion expected 2007
North Cape Shellfish Restoration Program
Aim
To restore lost biomass and ecological functions by establishing
and enhancing sustainable shellfish populations.
Target speciesBay scallop Argopecten irradians, restoration
Eastern oyster Crassostrea virginica, restoration
Quahog Mercenaria mercenaria, enhancement
South County salt ponds
Scallop restorationScallop restoration
2 phases; Direct seeding2 phases; Direct seeding Caged spawner sanctuary Caged spawner sanctuary
Phase 1, Direct seeding 2002 & 2003Phase 1, Direct seeding 2002 & 2003 Large scale seeding of 25 – 35 mm hatchery Large scale seeding of 25 – 35 mm hatchery
produced stock, fall of 1produced stock, fall of 1stst growing season growing seasonProvide broodstock for next breeding seasonProvide broodstock for next breeding season
Capture of spat for subsequent re-stocking of other Capture of spat for subsequent re-stocking of other ponds using ‘spat bags’ponds using ‘spat bags’
Dive surveys to monitor survivalDive surveys to monitor survival
North Cape Scallop Restoration ProjectDirect seeding of broodstock
Release sites, based on habitat assessments
Scallop direct seedingScallop direct seeding
20022002Point Judith PondPoint Judith Pond 680,000680,000
20032003Potter PondPotter Pond 286,300286,300Greenhill PondGreenhill Pond 188,980188,980Ninigret PondNinigret Pond 581,090581,090Quonochontaug PondQuonochontaug Pond 1,029,840 1,029,840
TotalTotal 2,766,200 2,766,200
Ninigret Pond; Release areas and indicating strata used for random transect surveys of scallop abundance
Results, AbundanceNinigret Pond ~ 10,000Quonochontaug Pond < 1,000Green Hill Pond ~ 0Potter Pond ~ 0Pt. Judith Pond 0
North Cape Scallop Restoration ProjectDirect seeding of broodstock - release sites
Phase 2 – Spawner sanctuary from 2004Phase 2 – Spawner sanctuary from 2004
3 components3 components
Broodstock cagesBroodstock cages
Maximize reproductive output by protecting broodstock Maximize reproductive output by protecting broodstock
Ninigret Pond 2004 to 2005, Quonochontaug Pond 2006 Ninigret Pond 2004 to 2005, Quonochontaug Pond 2006
Hatchery produced broodstock Hatchery produced broodstock
10,000 to 20,000 10,000 to 20,000 Settlement of larvae monitored using ‘spat bag arrays’Settlement of larvae monitored using ‘spat bag arrays’
4 array locations per pond4 array locations per pondSix bags / line, Retrieved every 4 weeks, 2 week overlapSix bags / line, Retrieved every 4 weeks, 2 week overlap
Annual diver surveys to estimate abundance, Annual diver surveys to estimate abundance, (Survival of spat to maturity), (Survival of spat to maturity),
Spawner sanctuaryMature broodstockMaintained in cages
for protection from predators
Spat Bag array
Schematic
Field example
FreeScallops
Ninigret Pond 2004 to 2006
Spawner cages10,000 broodstock 04 & 05
Spat bag arraysSame structure each year4 sites, 6 bags, 8 collections
Settlement indexΣ mean spat per bag
Dive surveys2004, 88 transects (6 strata)2005, 36 transects (3 strata- west basin)2006, 80 transects (6 strata)
2004, # Broodstock ~ 20,000 10,000 free (SE 5,500)
10,000 caged
Settlement Index32
2005, # Broodstock ~ 142,000 132,000 free (SE 55,000)
10,000 caged
Settlement Index137
2006, # Broodstock ~ 210,000 210,000 free (SE 102,000)
0 caged
Settlement Index35 + ?
Mean spat per bag from Ninigret Pond 2005
0.0
10.0
20.0
30.0
40.0
50.0
60.0
13 Jul2005
26 Jul2005
11 Aug2005
23 Aug2005
9 Sep2005
27 Sep2005
18 Oct2005
15 Nov2005
Collection date
Me
an
sp
at
pe
r b
ag
West End
Hall Point
Breachway
Aqualease
Mean spat per bag from Ninigret Pond 2004
0.0
10.0
20.0
30.0
40.0
50.0
60.0
13 Jul2004
26 Jul2004
11 Aug2004
24 Aug2004
7 Sep2004
22 Sep2004
5 Oct2004
2 Nov2004
Collection date
Me
an
sp
at
pe
r b
ag
West End
Hall Point
Breachway
Aqualease
Mean spat per bag from Ninigret Pond 2006
0.0
10.0
20.0
30.0
40.0
50.0
60.0
26 Jul2006
8 Aug2006
23 Aug2006
8 Sep2006
19 Sep2006
4 Oct2006
26 Oct2006
15 Nov2006
Collection Date
Me
an
sp
at
pe
r b
ag
West End
Hall Point
Breachway
Aqualease
?
Summary – Ninigret PondSummary – Ninigret Pond -04 and -05 results very encouraging-04 and -05 results very encouraging -06 results more difficult to interpret-06 results more difficult to interpret
Broodstock only in western basinBroodstock only in western basinSettlement only in central basinSettlement only in central basin
(larval transport / asymmetric survival)(larval transport / asymmetric survival)
Environmental conditions extreme in 06Environmental conditions extreme in 06Wettest year on recordWettest year on recordLow salinity (16 to 27 ppt), stable stratification,Low salinity (16 to 27 ppt), stable stratification,
evidence of anoxiaevidence of anoxiaMassive kill of scallops in central & northern basins Massive kill of scallops in central & northern basins
Quonochontaug PondQuonochontaug Pond
Similar design to Ninigret PondSimilar design to Ninigret PondSpawner sanctuarySpawner sanctuarySettlement surveysSettlement surveysMonitoring broodstock abundanceMonitoring broodstock abundance
2006, # Broodstock ~ 20,000
~ 400 free20,000 caged
Mean spat per bag from Quonochontaug Pond 2006
0.0
10.0
20.0
30.0
40.0
50.0
60.0
17 Aug2006
30 Aug2006
12 Sep2006
26 Sep2006
12 Oct2006
30 Oct2006
? Nov2006
Collection date
Mea
n sp
at p
er b
ag
West End
Spawner Sanctuary
Bill's Island
East End
?
ConclusionsConclusions Due to high predation rates, direct seeding of Due to high predation rates, direct seeding of
scallops was not a productive restoration methodscallops was not a productive restoration method Caged spawner sanctuary with relatively few Caged spawner sanctuary with relatively few
broodstock has been cost effective.broodstock has been cost effective.Produced appreciable spatfalls and population Produced appreciable spatfalls and population increasesincreases
Water quality. High flushing rates may reduce Water quality. High flushing rates may reduce likelihood of anoxic eventslikelihood of anoxic events
Benefit from a long term project commitmentBenefit from a long term project commitment