7 th SPC HOF meeting

1. 7th SPC HOF meeting Vulnerability of Freshwater Fisheries Peter Gehrke, Marcus Sheaves, James Terry, Joanna Ellison, David Boseto, Boga Figa and Jacob Wani

2. Main freshwater fisheries species

3. Direct climate factors considered

4. Effects of increasing temperature Increasing CO2 will promote growth of aquatic and riparian vegetation

5. Effects of rising sea level Barriers (waterfalls, cascades, weirs, culverts) may block retreat of freshwater habitats

6. Projected changes in rainfall

7. Effects of altered rainfall

8. Effects on fisheries habitats

9. Flow – maestro of freshwater habitats • Flow (rainfall, runoff, groundwater) determines the quantity of habitat available (depth, width, area, timing, connectivity, duration, rate of change, predictability) • Flow increase by 5% to > 20% in equatorial regions, 30% increase in Sepik-Ramu • Temperature, sea level, flow and cyclones determine the quality of available habitats

10. Flow responses to rainfall Daily flow, Nabukavesi Creek, Fiji Episodic flow, Tontouta River, New Caledonia Seasonal flow, Ba River, Fiji

11. SE Queensland floods, January 2011 Murphy’s Creek after flood Murphy’s Creek before flood

12. Projected habitat changes

13. Interactions in disturbed catchments • Removal of riparian vegetation causes increased warming (0.7 – 8.0˚C) • Reduced catchment vegetation allows increased runoff and erosion • Chronic exposure to contaminants reduces temperature tolerance (<5˚C) • Erosion leads to increased turbidity and sedimentation of pool habitats

14. Effects on diversity and abundance

15. Effects on diversity and abundance

16. Projected fisheries production

17. Putting climate change in perspective ‘In tropical systems it is possible that the effects of global climate change will be overshadowed by other, larger disturbances such as deforestation and land-use changes.’ ‘Currently, the magnitude of global climate change is such that most of its effects on freshwater fisheries could be easily masked by or attributed to other anthropogenic influences, such as deforestation, overexploitation and land use change’ (Fickeet al. 2007) Ficke AD, Myrick CA and Hansen LJ (2007) Potential impacts of global climate change on freshwater fisheries. Reviews in Fish Biology and Fisheries 17, 581-613.

18. Adaptation recommendations Improving habitat management to reduce exposure and sensitivity to climate change • Better knowledge of habitat use and fish responses to changes in habitat. • Plan future development to maintain habitat quantity and quality. • Modify barriers to allow fish and invertebrates to retreat upstream. • Revegetate cleared catchments to reduce exposure to warming. • Revegetate cleared land to reduce effects on temperature tolerances. • Engage with industry sectors to rehabilitate disturbed areas.

19. Supporting actions for fisheries management Build capacity of local communities to manage habitats and fisheries resources • Promote cross-sectoral approaches for villagers to manage fisheries and protect habitats. Adopt more efficient fishing methods and limit fishing effort • Regulate fishing gear to avoid negative interactions between increasing fishing pressure and climate change, and to reduce risk of over-exploitation. • Adapt fishing practices to harvest species tolerant to climate change. • Diversify fisheries for wider range of species and habitats e.g. river herring, eels.

20. Supporting actions for fisheries management Manage threats from invasive species • Investigate ways to manage low-value invasive alien species that may be favoured by climate change, to reduce impacts on food species. Improving post-harvest methods • Promote simple post-harvest methods, such as smoke curing, to reduce spoilage under higher temperatures. Monitor catches and measuring the success of management interventions • Implement simple systems for collecting basic information on catch and effort to assess effectiveness of adaptation.

21. Thank you