Projected changes to freshwater aquaculture Presented by Timothy Pickering
Dec 30, 2015
• This presentation is based on Chapter 11 ‘Vulnerability of aquaculture in the tropical Pacific to climate change’ in the book Vulnerability of Tropical Pacific Fisheries and Aquaculture to Climate Change, edited by JD Bell, JE Johnson and AJ Hobday and published by SPC in 2011.
• The authors of Chapter 11 are: Timothy D Pickering, Ben Ponia, Cathy A Hair, Paul C Southgate, Elvira S Poloczanska, Luc Della Patrona, Antoine Teitelbaum, Chadag V Mohan, Michael J Phillips, Johann D Bell and Sena De Silva
Authors
• Plans to greatly increase future production and livelihoods from freshwater aquaculture will stay on track, despite climate change.
• Freshwater aquaculture for food security and livelihoods will itself be an adaptation to the effects of climate change on coastal fisheries
• Freshwater aquaculture in the SW Pacific will generally benefit from climate change
Food security• Culture of lower-value
fish for food security is gaining higher priority
• Drivers are increasing populations, and a general decline in the coastal fisheries with which small Pacific islands were once blessed.
• Small-pond aquaculture is one of three major strategies now being proposed, along with:
- low-cost inshore FADs -increased local landings of
the region’s tuna catch. • Small-pond aquaculture will be
least in quantity• But greatest in quality
(freshness, nutrition) and availability (right on the doorstep of inland households)
10-15,000 fish farmsTrout/tilapiaHighlands
Cage-cultureHighlands
Livelihoods
Lake restocking to replace mossambicus with niloticus
Carp/tilapiaPNG
Tilapia/carp for Food security,
Recirculating
Red Tilapia – Cage Culture
Aquaponics
IntensiveIntensive flow-through
Semi-intensive culture in earthen
ponds
Tilapia for livelihoods
Lined ponds
Brackish ponds
Livelihoods
Milkfish for food securityFreshwater ponds
Cage culture for food, tuna-bait
Integrated taro/prawn pond culture Monoculture
Macrobrachium rosenbergii
Hatchery-Hatchery-based based cultureculture
Capture-based cultureCapture-based culture
Macrobrachium lar
Freshwater prawn Macrobrachium
SME approaches to food security
• Small household level aquaculture for subsistence consumption is only viable with on-going government support and subsidy of farm inputs, but is viewed as important by PICTs
• Inland aquaculture for livelihoods also contributes to food security
• The next challenge is to add a layer of viable SME-scale commercial-market aquaculture for peri-urban markets
Tilapia• It is very difficult to
estimate tilapia production in PICTs
• There are many small-scale farmers in very remote places
• There are repeated small harvests from each pond, without weighing
Tilapia• Fiji harvests fluctuate around 100 - 300T• PNG reports 100T per year to FAO, but this is a big
under-estimate• Tilapia aquaculture continues to expand in the region• Samoa now has 25 farms• Solomon Islands has begun an Inland Aquaculture
project to support emerging farmers• A tilapia hatchery has been established on Santo in
Vanuatu
Milkfish• 30 – 80 T per year
produced in intensive systems in Guam
• 5 – 15 T per year is produced in Kiribati
• Four farms now operate in Palau
• Capture-based culture trials are underway in Fiji, Solomon Islands and Tonga
Freshwater prawn• FW prawn farming in Fiji
produces about 25 T per year
• Vanuatu has now established a FW prawn hatchery
• Other PICTs are interested (PNG, Cook Islands).
• PICTs could produce several hundred T per year in total
Temperature
Spatial variation in temperature increase
2035
2035 2100
2050*
* Based on B1 2100 Source: Lough et al. (2011)
Greater climatic variation
• Extremes will become more extreme • Expect the unexpected! (Droughts, too)
Source: Gehrke et al. (2011)
Flows in Tontouta River, New Caledonia, after cyclones
Tilapia, freshwater prawn• Tilapia aquaculture in
the Pacific will not be particularly vulnerable, and may benefit from future climate change
• Temperatures suitable for tilapia and prawn farming will be extended to higher latitudes and higher altitudes.
• Higher rainfall means the amount of habitat and water available for inland aquaculture will increase
• Some areas with increased rainfall or cyclones may become more prone to flooding
DFF (Fiji) Ltd Prawn Farm
Cyclone Mick, December 2009
Tilapia, freshwater prawn
• Water column stratification from higher temperatures creates a de-oxygenated bottom layer in ponds. Fish are crowded and prawns die, unless energy is expended on pond aeration.
• Higher temperatures by 2100 may cause heat stress on prawns, and increase prevalence of pathogens causing disease
Tilapia, freshwater prawn
Milkfish• Increased temperatures
will extend the geographical range of milkfish breeding, and extend the season of fry collection for pond stocking
• Milkfish breed in seawater, so supply of fry is at risk from ocean acidification
How should we respond?• Prepare to increase flushing and aeration to
combat stratification and lower oxygen due to warmer temperatures and higher rainfall
Photo: Jacques Patrois
• Develop inland aquaculture industries based upon freshwater species, for food security and livelihoods, and for adaptation to the effects of climate change
How should we respond?
[But avoid spread of alien fish species to areas of high conservation value]
Outlook
• Aspirations for significant future production (1000 - 2000 T per high-island PICT) and livelihoods (between 10,000 to 20,000 persons part-time) from inland aquaculture are still likely to be realised.
Conclusion• Freshwater pond aquaculture is likely to be
favoured by climate change
Source: Pickering et al. (2011)