overfishing on caribbean and pacific coral reefs and ... · overfishing on caribbean and pacific...
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Overfishing on Caribbean and Pacific Overfishing on Caribbean and Pacific Coral Reefs and Potential SolutionsCoral Reefs and Potential Solutions
Alan FriedlanderAlan FriedlanderNOAA/NOS/NCCOS/CCMA NOAA/NOS/NCCOS/CCMA –– Biogeography BranchBiogeography Branch
Oceanic Institute, Waimanalo, HawaiiOceanic Institute, Waimanalo, Hawaii
• Declines in: – abundance – size – reproductive output
• Changes in:– sex ratio– behavior & distribution
• Changes in:– Trophic structure– Predator-prey dynamics– Habitat – Algal & inverts– Phase-shift
Direct Effects Ecosystem Effects
Increases in Fishing Capacity in the US Virgin Islands
1930s1958
1980s Today
1960 – Greater Lameshur Bay 1989-2000 – Monitoring Data
Snappers7%Herbivores
40%
Groupers3%
Secondary Consumers31%
Historical biological data in Virgin Islands provide Historical biological data in Virgin Islands provide earlier baseline for comparison w/ recent monitoringearlier baseline for comparison w/ recent monitoring
Beets and Friedlander in review
Groupers15%
Snappers9%
Secondary Consumers36%
Herbivores35%
OtherPredators
5%
OtherPredators15%
Changes in Grouper Species - U.S. Virgin Islands
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7
Coney
Rock Hind
Tiger
Yellow Fin
Red Hind
Nassau
Proportion of species observed
1958-601989-2000
290
300
310
320
330
340
350
360
370
380
390
1983 1985 1987 1989 1991 1993 1995 1997 1999 2001 2003
Year
Ave
rage
Tot
al L
engt
h (m
m)
OPEN CLOSED
Spawning aggregation closure for red hind in the US Virgin Islands resulted in increased fish size and more
males over time
Beets & Friedlander 1999, Sladek Nowlis & Friedlander 2005
Changes in Max. Size of Important Species in Virgin Islands National Park from 1989 to 2006
Friedlander and Beets 2008 % change in max. size (1989 to 2006)-30 -25 -20 -15 -10 -5 0
Spanish Hogfish
Mahogany Snapper
Grey Snapper
Graysby
Red Hind
1900 1920 1940 1960 1980 20000
5x103
10x103
15x103
20x103
100x103
200x103
300x103
400x103
500x103
600x103 Ulua - Jacks(Carangidae)
1900 1920 1940 1960 1980 20000
5000
10000
15000
20000
25000
30000
35000
Moi(Polydactylus sexfilis)
1900 1920 1940 1960 1980 20000
50x103
100x103
150x103
250x103
300x103
350x103
'o'io - Bonefish(Albula spp.)
1900 1920 1940 1960 1980 20000
10x103
20x103
30x103
40x103
50x103
60x103
kumu - Whitesaddle Goatfish(Parupeneus porphyreus)
Commercial Landings (lbs) for Select Targeted Fisheries Species in Hawai‘i
Friedlander et al. 2005
0.00
0.05
0.10
0.15
0.20
0.25
0.30
15 19 23 27 31 35 39 43 47 51 55
FemalesHermaphroditesMalesJuveniles
1962-68
0.00
0.05
0.10
0.15
0.20
0.25
15 19 23 27 31 35 39 43 47 51 55Length (cm)
FemalesHermaphroditesMalesJuveniles
1999
Friedlander & Ziemann 2003
Pro
porti
on o
f tot
alChange in Size and Sex Ratio of Harvested Change in Size and Sex Ratio of Harvested MoiMoi((PolydactylusPolydactylus sexfilissexfilis) on Oahu since the 1960) on Oahu since the 1960’’ss
Sex 1960s 1999 SizeJuv 6.4% 39.70% ***M 52.3% 33.80% ***H 17.8% 10.30% ***F 23.5% 16.20% ***
Loss of Herbivores lead to Algal-dominated Reef
Friedlander et al. 2008
Herbivore (>15 cm) biomass (t/ha)0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 0.40
Mac
roal
gae
cove
r (%
)
0
5
10
15
20
25
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
Apex predators Primary consumers Other secondary consumersConsumer category
Mea
n bi
omas
s (m
T/he
ctar
e
Northwestern Hawaiian Islands
Main Hawaiian Islands
Comparison of feedings groups in the MHI & NWHI
Friedlander& DeMartini 2002
P<0.05 P<0.05 P<0.05
7012%
83%55%
Status of 55 MHI Reef Fish Stocks relative to Unfished, Virgin Stocks in the NWHI
+
Friedlander et al. 2008
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
5 10 15 20 25 30 35 40 45 50 55 65 70 75 80 85 90 95 100+
Biomass status (% of NWHI)
Freq
uenc
y
Critical (42%)
Belowdesiredlevels(11%) Not
overfished(13%)
Hyper-abundant
(2%)
Depleted (33%)
KINGMAN REEF PALMYRA ATOLL
TABUAERANKIRITIMATI
0 people 10 people
6-8,000 people2,500 people
Hawaii
Declines in Fish Biomass across a Gradient of Human Impact in the Line Islands
0
1
2
3
4
5
6
Kingman Palmyra Tabuaeran Kiritimati
Bio
mas
s (t
ha-1
)
Apex predatorsSecondaryHerbivore
Population: 0 ~10 2,500 ~7,000
Sandin et al. 2008, DeMartini et al. 2008
Advances in fishing Advances in fishing technologytechnology
have reduced natural have reduced natural refugesrefuges
Percent Difference in Fish Assemblage Characteristics between MPAs and Open Areas in Hawaii
0%
100%
200%
300%
400%
Biomass No. > 20 cm Number ofindiv.
Species Diversity
Perc
ent d
iff. b
etw
een
MPA
s an
d op
en a
reas
Friedlander et al. 2006; 2007a 2007b
Recognize natural rhythms Recognize natural rhythms
Do not disturb basic renewal processesDo not disturb basic renewal processes
Monitor cues (moon, season, habitat)Monitor cues (moon, season, habitat)
Resource knowledgeResource knowledge
–– IntimacyIntimacy
–– AncestorsAncestors
Traditional Hawaiian Marine Traditional Hawaiian Marine Resource UseResource Use
Mo’omomi Fish Spawning Calendar (2000) Red = Peak Spawning Months, Orange = Other Spawning Months
Friedlander et al 2002, Poepoe et al 2003
Comparison of Fish Biomass in Areas under Various Management Regimes in Hawaii
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
No-take Customarystewardship
Partial protection Open access
mT/
hect
are
A A B B
F = 7.947P < 0.001
Adapted from Friedlander et al. 2003
Community based
• Overfishing has led to:– Reduced abundance, size & sex ratios of key sp.– Loss of ecosystem function
• Loss of top-down control by predators• Loss of herbivores lead to algal overgrowth
• MPAs highly effective in conserving populations• Traditional community-based management
effective in appropriate locations