Projected changes to freshwater aquaculture

Presented by Timothy Pickering

• 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

1. Current and projected freshwater aquaculture production

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

Livelihoods

Tilapia

Tilapia

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

2. Vulnerability of freshwater aquaculture

Projected changes

Source: Lough et al. (2011), Ganachaud et al. (2011)

Temperature

Spatial variation in temperature increase

2035

2035 2100

2050*

* Based on B1 2100 Source: Lough et al. (2011)

Rainfall

Spatial variation in rainfall (winter)

2035 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

3. Key responses and adaptations

How should we respond?

• Build fish ponds to avoid more severe floods

Photo: Avinash Singh

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]

4. Outlook for freshwater aquaculture

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)

Thank youThank you