Transcript Economic implications of projected changes to tuna

Projected changes to
freshwater fish stocks
Presented by
Peter Gehrke
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
Air Temperature (˚C)
Rainfall
(river flow)
2035
2050
2100
+0.5 – 1.0
+1.0 – 1.5
+2.5 – 3.0
+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)
Cyclones
El Niño
+8
+20 – 30
+18 – 38
+70 – 110
+23 – 51
+90 – 140
Increased intensity
Continuing feature but frequency & intensity uncertain
Flow – the Maestro
Effects of altered rainfall
Freshwater 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
2035
Lower
2050
Upper
Lower
2100
Upper
Lower
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%
-5%
10%
-5%
10%
-10%
>20%
Polynesia
French Polynesia
Likelihood
Confidence
Effects on fisheries
Projected fisheries changes
PICT
Production
(tonnes)
Average projected change (%)
2035
2050
2100
Melanesia
Fiji
4,146
0
0
Papua New Guinea
Solomon Islands
Vanuatu
Polynesia
French Polynesia
17,500
2,000
80
2.5
2.5
2.5
7.5
7.5
0
12.5
(5 – 20)
7.5
7.5
7.5
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.