Projected changes to aquaculture Based on Outline Freshwater

Projected changes to aquaculture

Based on…….

Outline • Freshwater aquaculture (tilapia, milkfish, freshwater prawn) • Vulnerability of freshwater aquaculture • Coastal aquaculture (marine shrimp, marine ornamentals) • Vulnerability of coastal aquaculture

Tilapia Food security • Cage culture • Household subsistence production

Livelihoods Tilapia • Cage culture • Semi-intensive ponds • Aquaponics

Tilapia • Tilapia farming is expanding in the region • PNG 10 -15, 000 households • Fiji produces 200 -300 tonnes per year • Vanuatu 65 -70 tonnes p. a. , hatchery established • Samoa has 25 farms

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

Conclusion • Freshwater pond aquaculture is likely to be favoured by climate change Source: Pickering et al. (2011)

Coastal aquaculture - livelihoods

Vulnerability of coastal aquaculture

Ocean acidification Source: IPCC (2007), Ganachaud et al. (2011)

Temperature 2035 2050* Spatial variation in temperature increase 2035 * Based on B 1 2100 Source: Lough et al. (2011)

Sea-level rise Projection 2035 2050 2100 IPCC 8 cm 18 -38 cm 23 -51 cm 20 -30 cm 70 -110 cm 90 -140 cm Semi-empirical

Marine shrimp • Expected to benefit in short term from higher temperatures • In the long-term, the main threats to shrimp culture are: – Sea-level rise – Ocean acidification – Pathogens – Scarcity of fishmeal?

Marine shrimp Now: crop in progress • Sea-level rise will make it difficult to: § § dry out ponds between crops harvest shrimp Now: pond preparation Future: poor pond prep. Future: difficult to harvest

How should we adapt • Modify shrimp ponds to drain well

Giant clams and marine ornamentals 2035 2050 2100 Effects due to: • • Increased temperature Ocean acidification Greater runoff More-intense cyclones

How should we adapt? • Grow-out animals at greater depth (cooler waters) • Identify sites where CO 2 is reduced

Outlook for coastal aquaculture

Conclusion • Scope for development over next 30 -40 years • Production efficiency is likely to be reduced