Projected changes to coastal fisheries

Based on......

Outline

• Main components of coastal fisheries• Indirect effects of climate change• Direct effects of climate change• Projected changes to coastal fisheries

production• Priority management measures

Coastal fisheries – Vanuatu

540 tonnes/yr

Subsistence

Commercial

What are coastal fisheries?• Demersal fish• Nearshore pelagics • Invertebrates

Species not considered • Deepwater snapper• Sharks

Demersal fish

Nearshore pelagic fish

Invertebrates

Coastal fisheries – Vanuatu

1,730 t/yr

755 t/yr

885 t/yr

Indirect effects of climate change

65% decline in abundance

and diversity of fishes

Pro

porti

onal

cha

nge

Time after extensive coral loss (years)

0 1 2 3 4 5 6 7 8 9 10

0.5

0

-0.5

-1

Macroalgae

Coral cover

Habitatcomplexity

Effects of habitat degradation

Pro

porti

onal

cha

nge

Time after extensive coral loss (years)

0 1 2 3 4 5 6 7 8 9 10

0.5

0

-0.5

-1

Coral reef fishes

Macroalgae

Coral cover

Habitatcomplexity

Effects of habitat degradation

Coral associatedHighly vulnerable

Reef associatedVulnerable

GeneralistsNot vulnerable

Catch composition

Fish composition – VanuatuPe

rcen

t

Catch

Species composition

Importance of herbivorous fish

Direct effects of climate change

Temperature

pH

Temperature (oC)

Maximum growth28-30oC

Acanthochromis polyacanthus

Projected Projected increaseincrease

33ooC by 2100C by 2100

Effects of temperature

Zarco Perello and Pratchett 2012

Maximum growth28-30oC

Effects of temperature

Fewer &smaller fishes

Declines in: growth lifespan reproduction

Projected Projected increaseincrease

33ooC by 2100C by 2100

Temperature (oC)

Zarco Perello and Pratchett 2012

Effects of temperature

Nor

mal

spa

wni

ng te

mpe

ratu

re

Effects of ocean acidificationAbalone

Byrne 2012

Effects of ocean acidification

Munday et al 2012

Projected coastal fisheries productionVanuatu

Fisheries % catch 2035 2050 2100 Main effects

Demersal fish 50 -2 to -5% -20% -20 to

-50%

Habitat loss and

degradation

Nearshore pelagic fish 31 0% -10% -15 to

-20%

Changes in distribution of

tuna

Invertebrates 19 0 to -5%

-5 to -10%

-10 to -20%

Ocean acidification

Priority management measures1. Protect structural complexity and biological

diversity of coral reefs, mangroves and seagrass to sustain fisheries and maximise adaptation potential

2. Recognise ecological importance of herbivorous fish and ensure stocks are sufficient to maintain ecosystem functions

3. Maintain adequate spawning stocks of all species to help overcome the shocks of greater climate extremes

Conclusions• Coastal fisheries are critically important for both

food security and livelihoods• Effects of climate change will add to existing

pressures (e.g. overfishing)• Improved catch data are needed for monitoring

effects of climate change on coastal fisheries: separate data for each main category of

coastal fisheries subsistence fisheries catches