7th SPC HOF meeting Noumea, 28 Feb -4 Mar Vulnerability of oceanic fisheries in the tropical Pacific to climate change Patrick Lehodey1, John Hampton2, Rich W Brill3, Simon Nicol2, Inna Senina1, Beatriz Calmettes1, Hans O Pörtner4, Laurent Bopp5, Tatiana Ilyina6, Johann D Bell2 and John Sibert7 1 Space Oceanography Division, CLS, France; 2Oceanic Fisheries Programme, SPC, New Caledonia; 3University of Miami, USA; 4Alfred Wegener Institute, Bremerhaven, Germany; 5CEA / IPSL, Paris, France; 6 Max Planck Institute for Meteorology, Germany; 7 Pelagic Fisheries Research Program, USA

Tuna and fisheries in the tropical Pacific O. Skipjack Katsuwonus pelamis Thunnus albacares Yellowfin Tropical sp. Bigeye Thunnus obesus Temperate sp. The main species targeted by the fishery are skipjack, yellowfin, albacore and bigeye tuna (Bluefin) Albacore Thunnus alalunga

Distribution of tuna catch ICCAT WCPFC IATTC IOTC bluefin yellowfin skipjack bigeye albacore WCPFC Catch in WCPO Tuna catch in the WCPC

Projection under IPCC scenarios IPSL Earth Climate Model Atmospheric CO2 concentration 1860-2000 : Measured 2000-2100 : IPCC A2 scenario Land surface Model (ORCHIDEE) Atmospheric model (LMDZ) Coupler (OASIS) Ocean General circulation Model (OPA) Sea-ice model (LIM) A2 scenario : PCO2 reaches 850 ppm in 2100 Ocean Biogeochemical (NPZD) Model Temperature Currents Productivity Dissolved Oxygen pH

Projected differences (°C) Temperature Projected differences (°C) 2035-2000 (A2 scenario) 2100-2000 (A2 scenario) + 0.5 / 1.5°C + 1.5 / 3.0°C Species Abundant occurrences (°C) Skipjack 20-29 Yellowfin 20-30 Bigeye 13-27 Albacore 15-21 Southern bluefin 17-20 Range of sea surface temperature where substantial commercial catches are made (source: Sund et al., 1981). IPCC (2007). Time series of global annual ocean heat content for the 0 to 700 m layer (observations). Development of tuna fisheries took place in a warming ocean the IPSL model you have used differ from the multi-model mean that Alex Ganachaud will be presenting – e.g. the multi-model mean projects  that SST will be 2.5-3.0 degrees warmer in 2100, whereas IPSL projects that this will not happen until 2100-2200.

Projected differences (micromole/L) 2100-2000 (A2 scenario) Oxygen Projected differences (micromole/L) 2100-2000 (A2 scenario) 5m 100m simulations from IPSL-CM4 global climate model. Species Fork length (cm) Lower lethal O2 levels (ml l-1) Skipjack 50 1.87 75 2.16 Yellowfin 1.14 1.77 Bigeye 0.40 0.50 Albacore 1.23 1.03 Less tolerant to low values decrease in surface increase in subsurface?? Most tolerant to low values … Standard hypothesis that phytoplankton growth uses constant C/N ratio But… increasing pCO2 could lead to changes of C/N ratio (Oschlies et al. 2008)… In that case the result is quite different! Projected changes to habitats that underpin the fishery used to show how indirect effects of climate change on stocks were assessed  

NPP Projected change (%) Ocean Productivity NPP Projected change (%) 2035-2000 (A2 scenario) 2100-2000 (A2 scenario) Tuna larvae Behrendfeld et al 2006. SeaWifs satellite based net primary production zooplankton Credit:Rudy Kloser and Jock Young CSIRO, Australia micronekton Projected changes to habitats that underpin the fishery used to show how indirect effects of climate change on stocks were assessed   decrease

Summary of expected impacts Observed effects of climate variability on tuna with ENSO Large-scale east-west displacements of skipjack in the Pacific are correlated with ENSO events. These displacements lead to large fluctuations in catches from the EEZs of PICTs. There is evidence that recruitment of tuna is influenced strongly by variability in ENSO. Vulnerability of oceanic fisheries to the effects of climate change Ocean temperature Projected changes should affect distribution of tuna by changing spawning location / success and accessibility to forage Good fishing grounds could be displaced further eastward or shift to higher latitudes. Dissolved oxygen Projected changes in O2 should have limited impact on tuna in WCPO (large uncertainty in the east) Ocean currents Impact on the dispersal (and mortality) of larvae and juveniles, Effect on the distribution of prey for adults. Ocean acidification Unknown. lower rates of growth and egg production? Noisier environment. Productivity and food web Projected decrease in productivity of the food web, thus less prey for larvae and adults Adults are highly mobile and can move to more favorable (new) foraging grounds. Examples of how projected changes to climate, ocean and habitats are expected to affect diversity and abundance of the key fish species

Integrated approach Modeling the interaction of oceanic variables with tuna biology and population dynamics SEAPODYM: Spatial Ecosystem And Populations Dynamics Model Age-structured Population Growth mortality by cohort Feeding Habitat = Food abundance x accessibility (T,DO) IF MATURE Seasonal switch Movement toward feeding grounds spawning grounds Mortality Spawning success Recruitment Spawning Habitat = Food & T for larvae Absence of adults’preys

1- Predict observed variability Integrated approach 1- Predict observed variability Currents Primary Production Dissolved O2 Food (mnecton) pH Temperature Age-structured Population Growth mortality by cohort Feeding Habitat = Food abundance x accessibility (T,DO) Spawning Habitat = Food & T for larvae Absence of adults’preys IF MATURE Seasonal switch Movement toward feeding grounds spawning grounds Mortality Spawning success Recrutement Brief description of the surface climate and/or ocean variables used in your assessment to estimate the direct effects of climate change 2 – Project Climate Change impact

Integrated approach Larvae density Adults biomass Skipjack Bigeye 2000 2050 2050 2000 2000 Adults biomass 2050 2050 Projected changes in the biomass (tonnes) and abundance of adult skipjack and bigeye tuna under the A2 emissions scenario . Simulations are based on average fishing effort for the period 1980-2000.

Projected change in tuna production SEAPODYM projected percentage changes in catches of skipjack and bigeye tuna, relative to recent catches (20-year average 1980-2000) Projected fishing effort = average 1980-2000 Skipjack tuna Estimated catch increases across the region until 2035 Greater increases for PICTs in the eastern than in the western Pacific. After 2050, the biomass of adults decreases significantly in the WCPO (-32% in 2100 under the A2 scenario) due to projected major changes in temperature, and productivity at lower and mid trophic levels. This result is of lower confidence due to the uncertainty of projected changes from climate and biogeochemical models. Bigeye tuna No obvious difference in the projected distribution and biomass of adult bigeye until 2035. In the 2nd half of Century, the western equatorial Pacific is predicted to become less favorable for spawning. But increase in survival of larvae in subtropical regions. An increasing mortality and eastward movement of older stages is predicted due to poorer habitat. This projection has a lower confidence due to uncertainty on projection of dissolved oxygen Projected changes i production of fish/invertebrates in 2035 and 2100 under B1 and A2 in summary table (with confidence and likelihood ratings).

Management recommendations for adaptation The overall management framework (WCPFC, FFA, the PNA and Te Vaka Moana groups) and all PICTs fishing authorities should explicitly consider the implications of climate change when developing management objectives and strategies over the coming years. According to projections for the 21st century, the boundary between the WCPFC convention area and the Inter-American Tropical Tuna Commission (IATTC) at 150⁰W would no longer be meaningful. Close cooperation (merging?) between the two commissions is highly necessary. It is a very high priority to maintain the bigeye tuna stock in the WCPO in a healthy state to avoid unfavorable combination of high fishing pressure and adverse environmental conditions in the coming decades. Effective conservation measures need to be implemented quickly because simulations show that it takes at least two decades for the WCPO bigeye stock to fully benefit from a reduction in fishing effort.  In addition to the key adaptation measures needed to reduce threats to catches, and harness the opportunities, provided by climate change, please also include the main management measures needed for the habitats that support your fishery

Management recommendations for adaptation PICTs and particularly the PNA need to further develop their management systems to ensure flexibility to cope with a potentially changing spatial distribution of the fishing effort. The transferability aspect of the PNA vessel days scheme (VDS) that allocates fishing effort among the EEZs according to agreed criteria will need to be implemented and adjusted in the future according to changing distributions Future socio-economic scenarios likely to drive future fishing effort in the region need to be developed.  In addition to the key adaptation measures needed to reduce threats to catches, and harness the opportunities, provided by climate change, please also include the main management measures needed for the habitats that support your fishery

? Management recommendations for adaptation Spatially-explicit management in archipelagic areas, currently beyond the mandate of WCPFC, are needed to monitor and assess potential sub-regional effects, e.g., increase of productivity due to projected increases in rainfall and run-off of the Sepik-Ramu and other large river systems. IPCC forcing (2°x month) 1 yr average Skipjack reanalysis at 2°x month 1 yr average ? New IPCC AR5 simulations Downscaling techniques Skipjack reanalysis at ¼° x week