Transcript Economic implications of projected changes to tuna

Projected changes
to aquaculture
Based on…….
Outline
• Freshwater aquaculture (tilapia, milkfish,
freshwater prawn)
• Vulnerability of freshwater aquaculture
• Coastal aquaculture/mariculture (giant clams,
corals, trochus, sea cucumbers)
• Vulnerability of coastal aquaculture
Tilapia
Food security
• Lake restocking to
replace Mossambique
Tilapia with Nile Tilapia
• PNG 10-15,000
households with tilapia
farms
Tilapia
Livelihoods
• Cage culture
• Semi-intensive
ponds
• Aquaponics
Tilapia
• Tilapia farming is expanding in the region
• Samoa has 35 farms
• Fiji produces 200-300 tonnes per year
• Solomon Islands has begun an Inland Aquaculture
project to support emerging farmers
• A tilapia hatchery has been established in Vanuatu
Milkfish
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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
• Some areas with
increased rainfall or
cyclones may become
more prone to flooding
DFF (Fiji) Ltd freshwater prawn Farm
Cyclone Mick, December 2009
Tilapia, freshwater prawn
• Stratification from higher temperatures
causes de-oxygenation – aeration needed
Milkfish
• Increased temperatures
will extend the
geographical range and
season of fry collection
• Risk from ocean
acidification?
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
Annual value
• Pearl and
shrimp farming
dominate
• Comprise >90%
of total value
Livelihoods
Shrimp
Pearl
Restocking
Sea cucumber
Giant clam
Trochus
Green snail
Vulnerability of mariculture
Marine fish, shellfish
• Mariculture of fish and
shellfish faces major
uncertainties
• Possible effects of
acidification on larval
fish and shells
Applies to giant clams and
cultured corals
Aquatic animal diseases
• Higher temperature are
likely to increase
prevalence of pathogens
• The nature and extent of
future disease risks are
not clear
White Spot Virus WSV
Adaptations
• Grow ornamentals at greater depth (cooler waters)
• Identify sites where CO2 is reduced
• Selective breeding for resilience to acidification
See Chapter 11 for vulnerability of
pearl oysters, shrimp, seaweed and
other commodities
Conclusion
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Mariculture has development potential in years ahead
But production efficiency is likely to be progressively
affected by climate change