Presented byPeter Gehrke
Projected changes to freshwater fish stocks
Key messages
• Freshwater fisheries are important in Fiji!!!
• Increased rainfall will increase freshwater habitats in tropical regions, less in subtropics
• Freshwater fish production increase by 5 – 20%
• Disturbed catchments restrict production
• Five adaptations to maximise positive outcomes and minimise negative effects
Freshwater fisheries in Fiji
• Fijian catch > 4,000 t/y, total 24,000 t/y
• 3% of wild catch value• Dominated by
invertebrates• Subsistence and
commercial value• Part of culture and
language
Climate change effects
Climate feature 2035 2050 2100
Air Temperature (˚C) +0.5 – 1.0 +1.0 – 1.5 +2.5 – 3.0
Rainfall (river flow)
+5% - 20% in equatorial
regions
+10% - 20% in equatorial regions
5% - 20% decrease in subtropics
Extremes (wet years, dry years) become more extreme
Sea level (cm)(salinisation)
+8+20 – 30
+18 – 38 +70 – 110
+23 – 51 +90 – 140
Cyclones Increased intensity
El Niño Continuing feature but frequency & intensity uncertain
Flow – the Maestro
Effects of altered rainfallFreshwater fish catches typically correlated to river flows
Temperature
• Sex ratios • Growth rates • Larvae feed earlier
(starvation?)• Muscle development• Pollutants increase
sensitivity (lower temp tolerance)
Sea level
Barriers (waterfalls, weirs, culverts) may block retreat of freshwater fish and clams
Projected habitat changes
PICT 2035Lower Upper
2050Lower Upper
2100Lower Upper
Melanesia
Fiji -5% 5% -5% 5% 5% 20%
PNG -5% 5-10% -5% 20% -5% 20%
Solomon Islands -5% 5-10% -5% 20% 5% 10%
Vanuatu -5% 5-10% -5% 5% 5% 10%
Polynesia
French Polynesia -5% 10% -5% 10% -10% >20%
Likelihood
Confidence
Effects on fisheries
Projected fisheries changes
PICT Production (tonnes)
Average projected change (%)
2035 2050 2100Melanesia
Fiji 4,146 0 0 12.5(5 – 20)
Papua New Guinea 17,500 2.5 7.5 7.5Solomon Islands 2,000 2.5 7.5 7.5
Vanuatu 80 2.5 0 7.5Polynesia
French Polynesia 100 2.5 2.5 7.5
Adaptation recommendations
1. Improve habitat management to reduce exposure and sensitivity to climate change
Adaptation recommendations
2. Build capacity of local communities to manage habitats and fisheries resources
Adaptation recommendations
3. Adopt more efficient fishing methods and limit fishing effort
Adaptation recommendations
4. Manage threats from invasive species
Adaptation recommendations
5. Monitor catches and measure the success of management interventions
In summary …
The outcomes of climate change for Fiji’s freshwater fisheries will be determined by the effectiveness of strategies to minimise human impacts at the catchment scale.
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