Projected changes to coastal fisheries
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Projected changes to coastal fisheries. Based on. What we will discuss. Projected changes to atmospheric and oceanic conditions. Ecosystems supporting fish. Fish stocks/aquaculture species. Implications for economic development, food security and livelihoods.

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Presentation Transcript


What we will discuss

Projected changes to atmospheric and oceanic conditions

Ecosystems supporting fish

Fish stocks/aquaculture species

Implications for economic development, food security and livelihoods

Adaptations and policies to reduce threats and capitalise on opportunities


Importance of coastal fisheries samoa
Importance of coastal fisheriesSamoa

8600

Production (tonnes)

2540

?

10

Aquaculture Freshwater Coastal Offshore


Importance of coastal fisheries is typical of region
Importance of coastal fisheriesis typical of region


What are coastal fisheries
What are coastal fisheries?

  • Demersal fish

  • Nearshorepelagics

  • Invertebrates

Species not considered

  • Deepwater snapper

  • Sharks





Coastal fisheries samoa
Coastal fisheries - Samoa

1665 t/yr

4420 t/yr

2550 t/yr



65% decline in abundance and diversity of fishes


Effects of habitat degradation

0.5

0

-0.5

-1

Macroalgae

Proportional change

Habitat

complexity

Coral cover

0 1 2 3 4 5 6 7 8 9 10

Time after extensive coral loss (years)


Effects of habitat degradation

0.5

0

-0.5

-1

Macroalgae

Proportional change

Habitat

complexity

Coral reef fishes

Coral cover

0 1 2 3 4 5 6 7 8 9 10

Time after extensive coral loss (years)


Catch composition

GeneralistsNot vulnerable

Reef associatedVulnerable

Coral associatedHighly vulnerable


Catch composition - Samoa

Catch

Species composition

Percentage

Source: Pratchett et al. 2011



Effects of temperature

Growth (mg/week)

Acanthochromis polyacanthus

Maximum growth

28-30oC

Projected increase

3oC by 2100

Temperature (oC)

Zarco Perello and Pratchett 2012


Effects of temperature

Declines in:

growth

lifespan

reproduction

Fewer &

smaller

fishes

Growth (mg/week)

Maximum growth

28-30oC

Projected increase

3oC by 2100

Temperature (oC)

Zarco Perello and Pratchett 2012


Effects of temperature

Normal spawning temperature


Effects of ocean acidification

Abalone

Byrne 2012




Priority adaptations
Priority adaptations

  • Protect the structural complexity and biological diversity of coral reefs, mangroves and sea grasses to sustain fisheries and maximize adaptation potential

  • Recognise ecological importance of herbivorous fishes and ensure their stocks of are sufficient to maintain ecosystem functions


Priority adaptations1
Priority adaptations

3. Diversify coastal fisheries to target species and habitats that will be least affected (or favoured) by climate change

4. Maintain adequate spawning stocks to overcome the shocks of greater climate extremes


Conclusions
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 is needed for monitoring effects of climate change on coastal fisheries

    • subsistence fisheries catches

    • separate data for each category of coastal fisheries and species wherever possible


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