Vulnerability of coastal fisheries Presented by Morgan Pratchett

Authors This presentation is based on Chapter 9 ‘Vulnerability of coastal fisheries 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 9 are: Morgan Pratchett, Philip Munday, Nicholas Graham, Mecki Kronen, Silvia Pinca, Kim Friedman, Tom Brewer, Johann Bell, Shaun Wilson, Joshua Cinner, Jeff Kinch, Rebecca Lawton, Ashley Williams, Lindsay Chapman, Franck Magron and Arthur Webb

200000 180000 160000 140000 120000 100000 80000 60000 40000 20000 0 Subsistence Commercial 300 Total Estimated value ($US millions) Annual Production (tonnes) Coastal Fisheries Production Gillett 2009 250 200 150 100 50 0 Commercial and susbsistence coastal fisheries Locally-based industrial tuna fishing

Le th ri Se nid a r Ac ran e an ida th e u r C ar ida an e g Lu ida tja e n M ida ug e ilid Sc ae H ol ari oc da en e tri d M ae ul Si lida ga e Ky nid ph ae os id La ae br C ida ha e ni Ba da e C listi ae d si ae on id a O e th er s Annual catch (kg) Diversity of coastal fisheries 60000 50000 40000 30000 20000 10000 0

Distinct fisheries sectors Demersal fish Nearshore pelagic fish Invertebrates

Demersal fish

Nearshore pelagic fish

Invertebrates

4 3, 5 3 2, 5 2 1, 5 1 0, 5 0 8, 15 8, 1 p. H 8, 05 8 7, 95 7, 9 Temperature now 2035 2050 7, 85 7, 8 2100 Ocean p. H Temperature change Direct effects of climate change

Indirect effects of climate change 60 1600 Coral cover (%) Seagrass area 40 1200 1000 30 800 20 600 Coral cover 400 10 200 0 now 2035 2050 0 2100 Areal extent (km 2) 1400 50

Effects of temperature 100 90 80 Growth (mg/week) 70 60 Acanthochromis polyacanthus Maximum growth 28 -30 o. C 50 40 30 Projected increase 3 o. C by 2100 20 10 0 22 24 26 28 30 32 Temperature (o. C) 34 36 38

Effects of temperature 100 Declines in: Fewer & • growth smaller • lifespan • reproduction fish 90 80 Growth (mg/week) 70 60 Maximum growth 28 -30 o. C 50 40 30 Projected increase 3 o. C by 2100 20 10 0 22 24 26 28 30 32 Temperature (o. C) 34 36 38

100 Normal spawning temperature Mortality of fertilised embryos (%) Effects of temperature 90 80 70 60 50 40 30 20 10 0 27, 9 29, 5 32, 0 32, 8 33, 9 Temperature (o. C) 34, 7

Effects of ocean acidification Other organisms affected: • Trochus • Oysters • Sea cucumbers • Crustaceans • Fish Source: Fine and Tchernov (2007)

Effects of habitat degradation Macroalgae Proportional change 0. 5 0 Habitat complexity -0. 5 Coral cover -1 0 1 2 3 4 5 6 7 8 Time after extensive coral loss (years) 9 10

Effects of habitat degradation Macroalgae Proportional change 0. 5 0 Habitat complexity -0. 5 Coral reef fishes Coral cover -1 0 1 2 3 4 5 6 7 8 Time after extensive coral loss (years) 9 10

65 % an dec d lin di e ve in rs ab ity u of nda fis nc h e

Projected coastal fisheries production

Priority adaptations • Protect structural complexity and biological diversity of coral reefs, mangroves and sea grasses to sustain fisheries and maximize adaptation potential • Recognise ecological importance of specific fish (e. g. herbivorous fish on coral reefs), and ensure stocks of these species are sufficient to maintain key ecosystem functions

Priority adaptations • Diversify coastal fisheries activities to target species and habitats that will be least affected, or favoured, by climate change • Build effects of climate change into fisheries management, particularly the need to maintain spawning stocks to overcome shocks of greater climate extremes

Conclusions • Coastal fisheries are critically important for both food security and livelihoods across the Pacific • Up until 2035, effects of climate change will probably be indiscernible against the backdrop of existing anthropogenic disturbances, but immediate action is required to minimize future effects of climate change on coastal fisheries

Conclusions • Improved data on catches are needed to predict and monitor the effects of climate change on coastal fisheries Data needed: § subsistence fisheries catches § separate data for the 3 distinct fisheries (or even species)