Transcript Day 3 06 Coastal Fisheries M. Pratchett

7th SPC HOF meeting
Effects of climate change on coastal fisheries
Morgan Pratchett, Philip Munday, Nicholas Graham, Mecki Kronen*, Silvia
Pinca*, Kim Friedman*, Tom Brewer, Johann Bell*, Shaun Wilson, Joshua
Cinner, Jeff Kinch, Rebecca Lawton, Ashley Williams*, Lindsay Chapman*,
and Franck Magron*
Climate change and coastal fisheries
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Four categories of coastal fisheries
1. Demersal finfishes
2. Nearshore pelagics
3. Targeted invertebrates
Shallow sub tidal and
Climate change and coastal4.
fisheries
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intertidal invertebrates
Climate change and coastal fisheries
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Others
Balistidae
Labridae
Mullidae
Kyphosidae
Holocentridae
Siganidae
Mugilidae
Carangidae
Lutjanidae
Serranidae
Scaridae
Acanthuridae
Lethrinidae
Proportional use species
Main types of species considered
Demersal finfishes
0.15
0.1
0.05
0
Major changes in environmental conditions
1. Sea surface temperature (SST)
Temperature increase (oC)
4
High emissions
A2
3
2
B1
Low emissions
1
0
1980
2000Climate 2020
2040 fisheries
2060
change and coastal
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2080
2100
Redistribution of species with increased temperature
Increasing latitude
Decreasing temperature
Climate change and coastal fisheries
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Redistribution of potential fisheries catch
By 2050, potential fisheries catches will decline by ~40% in the
tropical Pacific if species are free to move poleward with
increasing temperatures (Cheung et al. 2010)
Climate change and coastal fisheries
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Climate change and coastal fisheries
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Climate change and coastal fisheries
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Major changes in environmental conditions
1. Sea surface temperature (SST)
High emissions
Temperature increase (oC)
4
A2
3
2
B1
1
0
1980
Typical bleaching
threshold
2000
2020
2040
2060
2080
Climate change and coastal fisheries
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Low emissions
2100
Major changes in environmental conditions
2. Coral cover
0
-10
Severity of declines
-20
-30
-40
-50
Low emissions
-60
B1
-70
-80
-90
High emissions
-100
1980
2000
2020
2040
2060
Climate change and coastal fisheries
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2080
A2
2100
Major changes in environmental conditions
2. Coral cover
0
-10
Severity of declines
-20
-30
Effective local
management
-40
by teams of experts
-50
-60
B1
-70
-80
-90
-100
1980
A2
2000
2020
2040
2060
Climate change and coastal fisheries
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2080
2100
Declines in other habitats are also
expected to affect coastal fisheries
Habitat
2035
B1/A2
2100
B1
A2
Mangroves
-10 to > -10% -50 to -70% -60 to -80%
Seagrass
< -5 to -20%
-5 to -35%
-10 to -50%
Linkages between coral reefs, mangroves and seagrasses in
the life cycles of coastal fish and invertebrates
Climate change and coastal fisheries
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Climate change and coastal fisheries
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Fish declines exacerbated by
structural collapse of coral habitats
65% decline in abundance
and diversity of fishes
Climate change and coastal fisheries
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Major changes in environmental conditions
3. Aragonite saturation (ocean acidification)
5
Severity of declines
4.5
4
3.5
3
2.5
2
1980
2000
2020
2040
2060
Climate change and coastal fisheries
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2080
2100
Major changes in environmental conditions
3. Aragonite saturation (ocean acidification)
Loss of skeleton for corals growing under acidified conditions (Fine and Tchernov 2007)
Climate change and coastal fisheries
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Major changes in environmental conditions
3. Aragonite saturation (ocean acidification)
Climate change and coastal fisheries
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7th SPC HOF meeting
Effects of climate change on coastal fisheries
Demersal
finfish
Nearshore pelagic fish
Targeted
invertebrates
Shallow
Sub-tidal &
intertidal
invertebrates
WARM &
ARCH
PEQD, NPTG
& SPSG
-5%
0%
+40%
-5%
0%
2100 B1
-20%
-10%
+35%
-10%
-5%
2100 A2
-50%
-15%
+30%
-20%
-10%
2035 B1/A2
Low
Confidence
Medium
High
Climate change and coastal fisheries
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Very High
7th SPC HOF meeting
Effects of climate change on coastal fisheries

Coastal fisheries are sensitive to changes in
- habitat quality and quantity
- sea surface temperature
- seawater chemistry (pH)
- ocean currents and nutrient availability
 Up until 2035 effects of climate change may be
difficult to distinguish from sustained exploitation and
habitat degradation
 Effective local management will greatly reduce
longer-term impacts of climate change on coastal
fisheries
Climate change and coastal fisheries
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7th SPC HOF meeting
Adaptation and management recommendations
 Reverse or reduce local anthropogenic impacts
that reduce the structural complexity and
biological diversity of critical coastal habitats.
 Keep production of demersal finfish and
invertebrates within sustainable limits; rebuilding
populations of over-exploited species
 Diversify fishing activities (and livelihoods) to
reduce reliance on fisheries species that are
highly vulnerable to climate change
Climate change and coastal fisheries
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