Projected changes to coastal fisheries

Based on......

Outline Main components of coastal fisheries Indirect effects of climate change Direct effects of climate change Projected changes to coastal fisheries production Priority management measures

Coastal fisheries – Vanuatu 540 tonnes/yr Subsistence Commercial

What are coastal fisheries? Demersal fish Nearshore pelagics Invertebrates Species not considered Deepwater snapper Sharks

Demersal fish

Nearshore pelagic fish

Invertebrates

Coastal fisheries – Vanuatu 1,730 t/yr 755 t/yr 885 t/yr

Indirect effects of climate change Percentage

65% decline in abundance and diversity of fishes

Proportional change Time after extensive coral loss (years) Macroalgae Coral cover Habitat complexity Effects of habitat degradation

Proportional change Time after extensive coral loss (years) Coral reef fishes Macroalgae Coral cover Habitat complexity Effects of habitat degradation

Coral associated Highly vulnerable Reef associated Vulnerable Generalists Not vulnerable Catch composition

Fish composition – Vanuatu Percent Catch Species composition

Importance of herbivorous fish

Direct effects of climate change Temperature pH

Temperature ( o C) Maximum growth o C Acanthochromis polyacanthus Growth ( mg/week) Projected increase 3 o C by 2100 Effects of temperature Zarco Perello and Pratchett 2012

Maximum growth o C Growth ( mg/week) Effects of temperature Fewer & smaller fishes Declines in: growth lifespan reproduction Projected increase 3 o C by 2100 Temperature ( o C) Zarco Perello and Pratchett 2012

Effects of temperature Normal spawning temperature

Effects of ocean acidification Abalone Byrne 2012

Effects of ocean acidification Munday et al 2012

Projected coastal fisheries production Vanuatu Fisheries % catch Main effects Demersal fish50 -2 to -5% -20% -20 to -50% Habitat loss and degradation Nearshore pelagic fish 310%-10% -15 to -20% Changes in distribution of tuna Invertebrates19 0 to -5% -5 to -10% -10 to -20% Ocean acidification

Priority management measures 1.Protect structural complexity and biological diversity of coral reefs, mangroves and seagrass to sustain fisheries and maximise adaptation potential 2.Recognise ecological importance of herbivorous fish and ensure stocks are sufficient to maintain ecosystem functions 3.Maintain adequate spawning stocks of all species to help overcome the shocks of greater climate extremes

Conclusions Coastal fisheries are critically important for both food security and livelihoods Effects of climate change will add to existing pressures (e.g. overfishing) Improved catch data are needed for monitoring effects of climate change on coastal fisheries:  separate data for each main category of coastal fisheries  subsistence fisheries catches