Transcript 08. Projected changes to aquaculture

Projected changes to
aquaculture
Based on…….
Outline
• Summary of changes to surface climate and
the ocean expected to affect aquaculture
• Projected effects on pearl farming
• Projected effects on tilapia and milkfish
Projected changes
Source: Lough et al. (2011), Ganachaud et al. (2011)
Temperature
2035
2050*
Spatial variation
in temperature
increase
2035
* Based on B1 2100
2100
Source: Lough et al. (2011)
Ocean acidification
Ganachaud et al. (2011)
Potential impacts on pearl farming
• Poorer survival of spat due to
ocean acidification
• Reduced pearl quality because
nacre is composed of aragonite
• Effects of warmer water on nacre
quality
• Problems due to more intense
cyclones and increased
stratification (e.g. deoxygenation)
• BUT rise in sea level may improve
flushing of lagoons
Photo: Leanne Hunter
Thermocline
Source: Georgia Langdon
Options for responding to present-day
and future risks for pearl farming
Maintaining resilience of oysters
• Mapping to identify high
disease risk areas
• Regulate stock within farm
boundaries and carrying
capacity of lagoon
• Avoid overlapping farms
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Environmental monitoring
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Pearls
Seeded
a % of
g
hangin
pearl
total.
sa%
s and a
ea
vious y
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of the p
rs
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Anticipate and plan for losses
• Expect production losses from extreme events
and ‘unexpected’ causes
• Ensure that financial planning for enterprises
can absorb such shocks
Reduce the effects of OA and SST
• Identify sites where
conditions for nacre growth
may be better
• Progressively switch to
hatchery production and
selective breeding
• Grow pearls at greater
depth for final nacre
Photo: Leanne Hunter
Effects on giant clams
• Similar to pearl oysters
• Grow at greater depth (cooler waters)
• Identify sites where CO2 is reduced
Effects on tilapia
• Likely to benefit from
climate change
• Higher rainfall and
warmer temperatures
will allow farming in
more places and allow
faster production
Effects on tilapia
• Increased risks from flooding
• Stratification from higher temperatures
causes de-oxygenation
Effects on milkfish
• Increased temperatures
will extend the
geographical range and
season of fry collection
• Risk from ocean
acidification?
Conclusions for pearl farming
• Scope for development over next 30-40 years
• Production efficiency is likely to be reduced
Conclusions for freshwater fish
• Aquaponics and pond aquaculture are likely to
be favoured by climate change
Source: Pickering et al. (2011)