Transcript 08. Aquaculture

Projected changes to
aquaculture
Solomon Islands Government
Based on…….
Outline
• Freshwater aquaculture (tilapia, milkfish,
freshwater prawn)
• Vulnerability of freshwater aquaculture
• Coastal aquaculture (pearls, seaweed, marine
ornamentals)
• Vulnerability of coastal aquaculture
Tilapia
Food security
• Lake restocking to
replace Mossambique
Tilapia with Nile Tilapia
• Household subsistence
production
Tilapia
Livelihoods
• Cage culture
• Semi-intensive
ponds
• Aquaponics
Tilapia
• Tilapia farming is expanding in the region
• PNG 10-15,000
• Fiji produces 200-300 tonnes per year
• Samoa has 25 farms
• Hatchery established in Vanuatu
Milkfish
•
•
•
•
30 – 80 t per year in Guam
5 – 15 t per year in Kiribati
Four farms in Palau
Capture-based culture trials in Fiji,
Solomon Islands and Tonga
Brackish ponds
Freshwater ponds
Cage culture for food, tuna-bait
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
Milkfish
• Increased temperatures
will extend the
geographical range and
season of fry collection
• Risk from ocean
acidification?
Conclusion
• Freshwater pond aquaculture is likely to be
favoured by climate change
Source: Pickering et al. (2011)
Coastal aquaculture - livelihoods
Vulnerability of mariculture
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)
Acidification and temperature
• Acidification expected to affect pearl oyster
larvae, juveniles and adults
• Acidification and increased temperature likely
to reduce pearl quality
High-quality Fiji Pearls
Poor lustre, defects
Temperature and increased rainfall
Ice-ice
Kappaphycus seaweed is
vulnerable to:
• temperature >30oC
• lower salinity
These conditions cause
“ice-ice” and Epiphytic
Filamentous Algae (EFA)
outbreaks
EFA
Summary
• Pearls
2035
2050
2100
Effects due to:
• Seaweed
•Marine
ornamentals
•
•
•
•
•
Increased temperature
Ocean acidification
Greater runoff
Sea-level rise
More-intense cyclones
Key responses and adaptations
How should we respond?
• Expect production losses from extreme events
and ‘unexpected’ causes
• Ensure that financial planning for enterprises
can absorb such shocks
Photos: Cathy Hair
How should we adapt?
• Grow pearls at greater
depth for final nacre
How should we adapt?
• Long term data collection to identify sites where
conditions for nacre growth may be better
• Progressively switch to hatchery production and
selective breeding
How should we adapt?
• Select sites for seaweed farms near upwelling areas
and at low risk from increased freshwater runoff
• Use temperature- and salinity-tolerant strains to
avoid “ice-ice” and EFA
Photo: Gideon Tiroba
How should we adapt?
• Grow ornamentals at greater depth (cooler waters)
• Identify sites where CO2 is reduced
Outlook for mariculture
Pearl farming
• Difficult to predict
effects of future
production until more is
known about
consequences of ocean
acidification
Kappaphycus seaweed
• Medium-term production
targets of around 1000
tonnes per year should still
be achievable
• But not in the same places,
by the same methods, or
with the same varieties
Conclusion
• Scope for development over next 30-40 years
• Production efficiency is likely to be reduced