Transcript 08. Aquaculture

Projected changes to
aquaculture
Based on…….
Outline
• Freshwater aquaculture (tilapia, milkfish,
freshwater prawn)
• Vulnerability of freshwater aquaculture
• Coastal aquaculture (marine shrimp, marine
ornamentals)
• Vulnerability of coastal aquaculture
Tilapia
Food security
• Cage culture
• Household subsistence
production
Tilapia
Livelihoods
• Cage culture
• Semi-intensive
ponds
• Aquaponics
Tilapia
• Tilapia farming is expanding in the region
• PNG 10-15,000 households
• Fiji produces 200-300 tonnes per year
• Vanuatu 65-70 tonnes p.a., hatchery established
• Samoa has 25 farms
Freshwater prawn Macrobrachium
• Hatchery-based culture
(M. rosenbergii)
• Capture-based culture
(M. lar)
• Fiji produces about 25 t per year
Vulnerability of freshwater aquaculture
Tilapia, freshwater prawn
• Likely to benefit from
climate change
• Higher rainfall and
warmer temperatures
will allow farming in
more places and at
higher altitudes
Tilapia, freshwater prawn
• Increased risks from flooding
• Stratification from higher temperatures
causes de-oxygenation
How should we respond?
• Build fish ponds to avoid more severe floods
Photo: Avinash Singh
How should we respond?
• Increase aeration to
combat stratification
Conclusion
• Freshwater pond aquaculture is likely to be
favoured by climate change
Source: Pickering et al. (2011)
Coastal aquaculture - livelihoods
Vulnerability of coastal aquaculture
Ocean acidification
Source: IPCC (2007), Ganachaud et al. (2011)
Temperature
2035
2050*
Spatial variation
in temperature
increase
2035
* Based on B1 2100
2100
Source: Lough et al. (2011)
Sea-level rise
Projection
2035
2050
2100
IPCC
8 cm
18-38 cm
23-51 cm
20-30 cm
70-110 cm
90-140 cm
Semi-empirical
Marine shrimp
• Expected to benefit in short term from higher temperatures
• In the long-term, the main threats to shrimp culture are:
– Sea-level rise
– Ocean acidification
– Pathogens
– Scarcity of fishmeal?
Marine shrimp
Now: crop in progress
• Sea-level rise will make
it difficult to:


dry out ponds between
crops
harvest shrimp
Now: pond preparation
Future: poor pond prep.
Future: difficult to harvest
How should we adapt
• Modify shrimp ponds to drain well
Giant clams and marine ornamentals
2035
2050
2100
Effects due to:
•
•
•
•
Increased temperature
Ocean acidification
Greater runoff
More-intense cyclones
How should we adapt?
• Grow-out animals at greater depth (cooler waters)
• Identify sites where CO2 is reduced
Outlook for coastal aquaculture
Conclusion
• Scope for development over next 30-40 years
• Production efficiency is likely to be reduced