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THE KAHEKILI HERBIVORE FISHERIES MANAGEMENT AREA:
ENHANCING RESILIENCE OF A REEF SHOWING SIGNS OF STRESS IN WEST MAUI, HAWAIIDarla White1, Ivor Williams2, Russell Sparks1
1Hawaii Department of Land and Natural Resources, Division of Aquatic Resources, Maui, 130 Mahalani St., Wailuku HI 967932NOAA National Marine Fisheries Service, Coral Reef Ecosystem Division, 1125B Ala Moana Blvd., Honolulu HI 96814
• Data from the Coral Reef
Assessment and Monitoring
Program showed significant
declines in coral cover (~40% loss
from 1993 – 2005) at the Kahekili
Beach Park Site.
• Regular summer macroalgal
blooms at Kahekili (figures below)
contributed to coral decline.
• Reef stressed and declining, but not
yet fully degraded.
The Kahekili Herbivore Fisheries Management Area
Prohibited
Activities Include:
•Removing or
killing any surgeon
fish, parrotfish, or
chub
•Removing or
killing any sea
urchins
•Fish feeding
Allowed Activities
Include:
•Fishing for or
Removing all other
legally harvested
marine life.
•Using bait and/or
other fish
attractants while
legally fishing.
Abstract
The state of Hawaii recently implemented a fishery management effort to increase the resilience of a coral reef at Kahekili West Maui showing clear evidence of decline and vulnerability. Between 1994
and 2005, ~40% of live coral cover was lost there, coincident with repeated summer blooms of invasive macroalgae. In response, the Kahekili Herbivore Fisheries Management Area (KHFMA) was
established in July 2009. Monitoring begun 18 months before establishment of the KHFMA provides clear evidence of incipient recovery: increased biomass of herbivorous fishes, and cover of benign
algae such as crustose corallines. Outreach partnership efforts with the Coral Reef Alliance and the Ka‘anapali Makai Watch program, have increased general public and fisher awareness and support for
herbivore management efforts. Monitoring data coupled with the innovative strategy have resulted in national recognition and the designation of West Maui's watershed as a priority Pacific watershed by
the US Coral Reef Task Force. Watershed projects designed to reduce land-based stressors should result in further increases in ecosystem resiliency.
Algal blooms at Kahekili in
(left) 2005 of the invasive
Acanthophora spicifera, and
(right) 2001of the native
species Cladophora sericea.Photos R. Sparks, J. Smith.
Figure at right shows trends
in coral and macroalgal
cover prior to creation of
the KHFMA
Bullethead Parrotfish
(Chlorurus spilurus) initial
phase (upper photo) and
terminal phase (lower
photo). Photos J.E. Randall.
Figure to the right shows
steady increase in
contibution of large
individuals to total species
biomass.
Honokowai Park
Lahaina
Wastewater
Reclamation
Facility
Kahekili Beach Park
Keka`a Point (Black Rock)
Background
The causes and consequences of those algal blooms are complex, it is reasonable
to expect that protection of reef herbivores can reduce the severity and frequency
of algal blooms and, therefore, can help to check and potentially reverse the
downward trend in condition of Kahekili reefs.
o Initially depleted herbivorous fish stocks compared to Marine Life
Conservation Areas
o Acanthophora spicifera is a preferred edible of herbivores
o Reef still had the structural complexity to support fish life
Factors Favorable to Herbivore Management Strategy
-
0.25
0.50
0.75
1.00
1.25
1.50
6-10 11-15 16-20 21-25 26-30 31-35 36-40
2008/9
-
0.25
0.50
0.75
1.00
1.25
1.50
6-10 11-15 16-20 21-25 26-30 31-35 36-40
2010
-
0.25
0.50
0.75
1.00
1.25
1.50
6-10 11-15 16-20 21-25 26-30 31-35 36-40
2011
-
0.25
0.50
0.75
1.00
1.25
1.50
6-10 11-15 16-20 21-25 26-30 31-35 36-40
2012
-
0.25
0.50
0.75
1.00
1.25
1.50
6-10 11-15 16-20 21-25 26-30 31-35 36-40
2013
0%
2%
4%
6%
8%
10%
12%
- 2 4 6 8 10
CC
A C
ove
r (%
)
Parrotfish Biomass (gm-2)
Relationships Between Parrotfish Biomass & CCA Cover
-
5
10
15
20
25
2008 2009 2010 2011 2012 2013
Bio
mas
s (g
m-2
)
Surgeonfish Biomass at KHFMA
-
2
4
6
8
2008 2009 2010 2011 2012 2013
Bio
mas
s (g
m-2
)
Parrotfish Biomass at KHFMA
Interim Results
Clear increase in parrotfish biomass and
slightly less in surgeonfish.
Increase in biomass of larger size classes of
parrotfish – is evidence that more fishes are reaching older and larger life stages = increased grazing and reproductive capacity
-
0.100
0.200
0.300
0.400
0.500
0.600
2007 2008 2009 2010 2011 2012 2013 2014
Co
ver
(%)
Benthic Cover at KHFMA (all habitats combined)
HardCoralCCA
Turf
Reef Benthos
• Initial decline in coral cover, which has subsequently
flattened out.
• Macroalgal cover has declined to near zero (but was
neveauir >~5% across whole KHFMA)
• No macroalgal blooms since 2006
• CA has increased to around 8% from ~ 2% pre closure
Looking ahead. The mechanisms by which protection of herbivores could
increase reef resilience and coral recovery involve (i)
promotion of benign algal forms (e.g., crustose coralline algae
[CCA], which are important for coral settlement), and (ii)
reduction of algae that can overgrow, smother, or otherwise
negatively affect corals. The full effects of the KHFMA on
fishes and corals will only become evident over a much longer
period of time. However, results show a strong positive
relationship between total parrotfish biomass and total CCA
cover (see fig ->), suggesting that further increases in
parrotfish biomass will have additional positive effects.
The Hawai’i Division of Aquatic Resources (DAR) in partnership with the University
of Hawai’i began a comprehensive monitoring program at Kahekili in January 2008.
That program has been maintained using consistent methods and survey design, but
implemented by DAR and NOAA CRED personnel since 2010. Monitoring involves
1–2 “rounds” per year, generally spring and late summer, with each round comprising
co-located surveys of fishes, urchins, and benthos (e.g., corals and algae) at~80–100
haphazardly located sites. The figure below shows data from April 2012: each bubble
orresponds to either fish biomass or algal cover (%).
Coral Reef Monitoring
West Maui Priority Watershed
The West Maui region, including Kahekili, became a ‘priority site’ for the state
coral management program in 2010. In 2011 the US coral reef task force picked
West Maui as one of 2 Pacific priority watersheds. Those designations and other
factors contributed to a 2012 MOA between DLNR and the Army Corps to work
collaboratively on a planning initiative for watersheds from Waihikuli to Honolua,
known at the West Maui Ridge to Reef Initiative.
A working group created to help advise the process is composed of land
owners/managers, resource users, farmers, and various agency representatives. Its
focus remains on watershed management activities with direct links to adjacent
coral reefs. Active outreach partnership efforts with the Coral Reef Alliance and the
Ka‘anapali Makai Watch program, have increased general public and fisher
awareness and support for herbivore management efforts. Thus, the KHFMA has
contributed to and spurred on more proactive management of the wider area.