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Projected changes to freshwater fish habitats and stocks

Projected changes to freshwater fish habitats and stocks. Presented by Peter Gehrke. Authors.

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Projected changes to freshwater fish habitats and stocks

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  1. Projected changes to freshwater fish habitats and stocks Presented by Peter Gehrke

  2. Authors This presentation is based on Chapter 7 ‘Vulnerability of freshwater and estuarine fish habitats in the tropical Pacific to climate change’ and Chapter 10 ‘Vulnerability of freshwater and estuarine fisheries in the tropical Pacific to climate change’ in the book Vulnerability of Tropical Pacific Fisheries and Aquaculture to Climate Change, edited by JD Bell, JE Johnson and AJ Hobday and published by SPC in 2011. The authors of Chapter 7 are: Peter C Gehrke, Marcus J Sheaves, James P Terry, David T Boseto, Joanna C Ellison, Boga S Figa and Jacob Wani. The authors of Chapter 10 are: Peter C Gehrke, Marcus J Sheaves, David T Boseto, Boga S Figa and Jacob Wani.

  3. Key messages • Freshwater fisheries are important!!! • Increased rainfall will increase freshwater habitats in tropical regions, less in subtropics • Freshwater fish production may increase by ~12% • Disturbed catchments restrict production • Five adaptations to maximise positive outcomes and minimise negative effects

  4. Importance of freshwater fisheries • Catch 24,000 tonnes per year • 4% of GDP derived from fisheries • Consumption up to 100 kg per year • Part of culture and language Photo Jacob Wani

  5. Diversity of freshwater habitats

  6. Flow – the Maestro

  7. Effects on freshwater are different! • Climate change will affect the quantity of freshwater habitat available to fisheries • Changes in water quality and habitat quality will be secondary to changes in flow

  8. Freshwater habitats Photo Boga Figa

  9. Fish migration and habitat connectivity Source: Gehrke et al 2011

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

  11. Climate change effects

  12. Temperature Photo: David Boseto • Increasing CO2 will promote growth of aquatic and riparian vegetation

  13. Sea level • Barriers (waterfalls, weirs, culverts) may block retreat of freshwater habitats

  14. Rainfall 2050 2050 Source: Lough et al. (2011)

  15. Effects of altered rainfall Source: Gehrke et al 2011

  16. Projected habitat changes

  17. Interactions in disturbed catchments Source: Google Earth

  18. Effects on fisheries Photo: Erin Michelle Smith

  19. Projected fisheries changes

  20. Adaptation recommendations • Maintain vegetation in catchments to avoid sediments and nutrients entering waterways Photo: Joanna Ellison

  21. Adaptation recommendations • Build capacity of local communities to manage habitats and fisheries resources Photo: Joanna Ellison

  22. Adaptation recommendations • Adopt more efficient fishing methods and limit fishing effort Photo: Boga Figa Photo: Boga Figa

  23. Adaptation recommendations • Manage threats from invasive species Photo: Boga Figa

  24. Adaptation recommendations • Monitor catches and measure the success of management interventions Photo: Jacob Wani

  25. 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.’ (Ficke et al. 2007) Photo: Jacob Wani

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