1. Projected changes to coastal fisheries

2. Based on......

3. 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

4. Coastal fisheries catch – Cook Islands
Commercial
Subsistence
Source: Gillett (2006)

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

6. Demersal fish
Solomons – spearing, netting, line fishing targeting snapper, groupers, coral trout

7. Nearshore pelagic fish
Solomons – YF and skipjack tuna, Spanish mackerel (king fish), rainbow runner, mahi mahi and bait fish for pole and line tuna fishery (small pelagics – booma and roma)

8. Invertebrates
Solomons – beche de mer, trochus, spiney lobster, mud carb, giant clams (food), whelks, oysters

9. Coastal fisheries catches – Cook Islands
14 t/yr
146 t/yr
240 t/yr
Pratchett et al. 2011

10. Demersal fish catch composition
Availability
Catch
Percentage
Pratchett et al. 2011

11. Indirect effects of climate change
% Coral cover
Area (km2)

13. 65% decline in abundance and diversity of fishes

14. Effects of habitat degradation
0.5
-0.5 -1
Macroalgae
Proportional change
Habitat
complexity
Coral cover
Time after extensive coral loss (years)

15. Effects of habitat degradation50
-50
-100
Macroalgae
Percentage change
Habitat
complexity
Coral reef fishes
Coral cover
Time after extensive coral loss (years)

16. Catch composition Generalists Not vulnerable
Reef associated Vulnerable
Coral associated Highly vulnerable

17. Importance of herbivorous fish

18. Herbivorous fish in Cook Islands
Availability
Catch
Percentage

19. Direct effects of climate change
Temperature pH

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

21. Effects of temperature
Fewer &
smaller
fishes
Declines in:
growth
lifespan
reproduction
Growth (mg/week)
Maximum growth
28-30oC
Projected increase
3oC by 2100
Temperature (oC)
Zarco Perello and Pratchett 2012

22. Effects of temperature
Normal spawning temperature

23. Effects of ocean acidification
Abalone
Byrne 2012

24. Effects of ocean acidification
Munday et al. 2012

25. Projected coastal fisheries production Cook Islands
% catch
2035
2050
2100
Main effects
Demersal fish 36
-2 to
-5%
-20%
-20 to
-50%
Degradation of coral reefs
Nearshore pelagic fish* 60
+15 to +20%
+20%
+10%
Changes in distribution of tuna
Invertebrates 4
0 to
-5 to -10%
-10 to
Ocean acidification
*Based on initial preliminary modelling for skipjack tuna

26. Ciguatera fish poisoning

27. Factors affecting ciguatera
Dead coral & seaweed surfaces
Nutrients
Water temperature
From land-based activities and sewage

28. Priority management measures
Protect structural complexity and biological diversity of coral reefs to sustain fisheries
Maintain adequate spawning stocks to help overcome shocks of greater climate extremes
Recognise ecological importance of herbivorous fish and ensure stocks are sufficient to maintain ecosystem functions

29. Conclusions
Coastal fisheries are important for 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