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Projected changes to coastal fisheries

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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Projected changes to coastal fisheries

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  1. Projected changes to coastal fisheries

  2. Based on......

  3. 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

  4. Importance of coastal fisheriesSamoa 8600 Production (tonnes) 2540 ? 10 Aquaculture Freshwater Coastal Offshore

  5. Importance of coastal fisheriesis typical of region

  6. What are coastal fisheries? • Demersal fish • Nearshorepelagics • Invertebrates Species not considered • Deepwater snapper • Sharks

  7. Demersal fish

  8. Nearshore pelagic fish

  9. Invertebrates

  10. Coastal fisheries - Samoa 1665 t/yr 4420 t/yr 2550 t/yr

  11. Indirect effects of climate change Coral cover

  12. 65% decline in abundance and diversity of fishes

  13. 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)

  14. 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)

  15. Catch composition GeneralistsNot vulnerable Reef associatedVulnerable Coral associatedHighly vulnerable

  16. Catch composition - Samoa Catch Species composition Percentage Source: Pratchett et al. 2011

  17. Direct effects of climate change pH Temperature

  18. Effects of temperature Growth (mg/week) Acanthochromis polyacanthus Maximum growth 28-30oC Projected increase 3oC by 2100 Temperature (oC) Zarco Perello and Pratchett 2012

  19. 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

  20. Effects of temperature Normal spawning temperature

  21. Effects of ocean acidification Abalone Byrne 2012

  22. Effects of ocean acidification Munday et al 2012

  23. Projected coastal fisheries productionSamoa

  24. 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

  25. 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

  26. 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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