7 th SPC HOF meeting Effects of climate change on coastal fisheries

Climate change and coastal fisheriesMorgan.Pratchett@jcu.edu.au

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*

7th SPC HOF meeting Effects of climate change on coastal fisheries

Climate change and coastal fisheriesMorgan.Pratchett@jcu.edu.au

Four categories of coastal fisheries

1. Demersal finfishes 2. Nearshore pelagics

3. Targeted invertebrates 4. Shallow sub tidal and intertidal invertebrates

Climate change and coastal fisheriesMorgan.Pratchett@jcu.edu.au

Pro

port

iona

l use

spe

cies

Main types of species considered Demersal finfishes

Climate change and coastal fisheriesMorgan.Pratchett@jcu.edu.au

Tem

pera

ture

incr

ease

(o C

)T

empe

ratu

re in

crea

se (

o C)

Major changes in environmental conditions1. Sea surface temperature (SST)

High emissions

Low emissions

B1

A2

Climate change and coastal fisheriesMorgan.Pratchett@jcu.edu.au

Redistribution of species with increased temperature

Increasing latitude

Decreasing temperature

Climate change and coastal fisheriesMorgan.Pratchett@jcu.edu.au

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 fisheriesMorgan.Pratchett@jcu.edu.au

Climate change and coastal fisheriesMorgan.Pratchett@jcu.edu.au

Climate change and coastal fisheriesMorgan.Pratchett@jcu.edu.au

Tem

pera

ture

incr

ease

(o C

)T

empe

ratu

re in

crea

se (

o C)

B1

A2

Typical bleaching threshold

High emissions

Low emissions

Major changes in environmental conditions1. Sea surface temperature (SST)

Climate change and coastal fisheriesMorgan.Pratchett@jcu.edu.au

Sev

erity

of

decl

ines

Sev

erity

of

decl

ines

High emissions

B1

A2

Low emissions

Major changes in environmental conditions2. Coral cover

Climate change and coastal fisheriesMorgan.Pratchett@jcu.edu.au

A2

Sev

erity

of

decl

ines

Sev

erity

of

decl

ines

Major changes in environmental conditions2. Coral cover

B1

Effective local managementby teams of experts

Climate change and coastal fisheriesMorgan.Pratchett@jcu.edu.au

Declines in other habitats are also expected to affect coastal fisheries

Habitat2035 2100B1/A2 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 fisheriesMorgan.Pratchett@jcu.edu.au

Climate change and coastal fisheriesMorgan.Pratchett@jcu.edu.au

Fish declines exacerbated by structural collapse of coral habitats

65% decline in abundance and diversity of fishes

Climate change and coastal fisheriesMorgan.Pratchett@jcu.edu.au

Sev

erity

of

decl

ines

Sev

erity

of

decl

ines

Major changes in environmental conditions3. Aragonite saturation (ocean acidification)

Climate change and coastal fisheriesMorgan.Pratchett@jcu.edu.au

Major changes in environmental conditions3. Aragonite saturation (ocean acidification)

Loss of skeleton for corals growing under acidified conditions (Fine and Tchernov 2007)

Climate change and coastal fisheriesMorgan.Pratchett@jcu.edu.au

Major changes in environmental conditions3. Aragonite saturation (ocean acidification)

Climate change and coastal fisheriesMorgan.Pratchett@jcu.edu.au

Demersal finfish

Nearshore pelagic fish

Targeted invertebrates

Shallow Sub-tidal &

intertidal invertebrates

WARM & ARCH

PEQD, NPTG & SPSG

2035 B1/A2 -5% 0% +40% -5% 0%

2100 B1 -20% -10% +35% -10% -5%

2100 A2 -50% -15% +30% -20% -10%

Low Medium High Very High

Confidence        

7th SPC HOF meeting Effects of climate change on coastal fisheries

Climate change and coastal fisheriesMorgan.Pratchett@jcu.edu.au

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 fisheriesMorgan.Pratchett@jcu.edu.au

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