Projected changes to coastal fisheries Based on What

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 Adaptations and policies to reduce threats and capitalise on opportunities

Importance of coastal fisheries Samoa 10000 8600 Production (tonnes) 9000 8000 7000 6000 5000 4000 2540 3000 2000 1000 0 ? 10 1 Freshwater Aquaculture 2 3 Coastal 4 Offshore

Importance of coastal fisheries is typical of region Estimated value ($US millions) 300 250 200 150 100 50 0 Commercial and susbsistence coastal fisheries Locally-based industrial tuna fishing

What are coastal fisheries? • Demersal fish • Nearshore pelagics • Invertebrates Species not considered • Deepwater snapper • Sharks

Demersal fish

Nearshore pelagic fish

Invertebrates

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

Indirect effects of climate change 60 Coral cover (%) 50 40 30 20 Coral cover 10 0 now 2035 2050 2100

65 % an de d cli di ne ve i rs n a ity b of und fis an he c s e

Effects of habitat degradation Macroalgae Proportional change 0. 5 0 Habitat complexity -0. 5 Coral cover -1 0 1 2 3 4 5 6 7 8 Time after extensive coral loss (years) 9 10

Effects of habitat degradation Macroalgae Proportional change 0. 5 0 Habitat complexity -0. 5 Coral reef fishes Coral cover -1 0 1 2 3 4 5 6 7 8 Time after extensive coral loss (years) 9 10

Others Caesionidae Balistidae Chanidae Labridae Kyphosidae Siganidae Mullidae Holocentridae Scaridae Mugilidae Lutjanidae Carangidae Acanthuridae Serranidae Lethrinidae Average annual catch (kg/ year) 60000 Catch composition 50000 40000 Generalists Not vulnerable 30000 20000 10000 Reef associated Vulnerable 0 Coral associated Highly vulnerable

Catch composition - Samoa 60. 0 50. 0 Percentage 40. 0 Catch Species composition 30. 0 20. 0 10. 0 Surgeonfish Parrotfish Snappers Emperors Triggerfish Groupers Red mullets. Squirrelfish Rabbitfish Drummers Wrasses (H) (H) Source: Pratchett et al. 2011

4 3. 5 3 2. 5 2 1. 5 1 0. 5 0 8. 15 8. 1 p. H 8. 05 8 7. 95 7. 9 Temperature now 2035 2050 7. 85 7. 8 2100 Ocean p. H Temperature change Direct effects of climate change

Effects of temperature 100 90 80 Growth (mg/week) 70 60 Acanthochromis polyacanthus Maximum growth 28 -30 o. C 50 40 30 Projected increase 3 o. C by 2100 20 10 0 22 24 26 28 30 32 34 36 38 Temperature (o. C) Zarco Perello and Pratchett 2012

Effects of temperature 100 Declines in: growth lifespan reproduction 90 80 Growth (mg/week) 70 60 Maximum growth 28 -30 o. C 50 Fewer & smaller fishes 40 30 Projected increase 3 o. C by 2100 20 10 0 22 24 26 28 30 32 34 36 38 Temperature (o. C) Zarco Perello and Pratchett 2012

100 Normal spawning temperature Mortality of fertilised embryos (%) Effects of temperature 90 80 70 60 50 40 30 20 10 0 27. 9 29. 5 32. 0 32. 8 33. 9 Temperature (o. C) 34. 7

% larval survival/development Effects of ocean acidification Abalone 80 20 deg C 22 deg C 24 deg C 70 60 50 40 30 20 10 0 p. H 8. 2 p. H 7. 8 p. H 7. 6 Byrne 2012

Effects of ocean acidification Munday et al 2012

Projected coastal fisheries production Samoa Fisheries Demersal fish Nearshore pelagic fish Invertebrates % 51 2035 -2 to 5% 2050 -20% 30 +15 to +20% 19 0 to 5% -5 to 10% 2100 Main effects -20 to 50% Habitat loss and degradation +10% -10 to 20% Changes in distribution of tuna Declining aragonite saturation

Priority adaptations 1. Protect the structural complexity and biological diversity of coral reefs, mangroves and sea grasses to sustain fisheries and maximize adaptation potential 2. Recognise ecological importance of herbivorous fishes and ensure their stocks of are sufficient to maintain ecosystem functions

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 • 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