7th SPC HOF meeting Noumea, 28 Feb -4 Mar

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7th SPC HOF meetingNoumea, 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
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Tuna and fisheries in the tropical Pacific O.
Katsuwonus pelamis
Thunnus albacares
Tropical sp.
Temperate sp.
(Bluefin)
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Distribution of tuna catch
ICCAT
WCPFC
IATTC
IOTC
bluefin
yellowfin
skipjack
bigeye
albacore
WCPFC
Tuna catch in the WCPC
Catch in WCPO
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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)
Ocean General circulation Model (OPA)
Sea-ice model (LIM)
A2 scenario PCO2 reaches 850 ppm in 2100
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Temperature
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).
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Oxygen
Species Fork length (cm) Lower lethal O2 levels (ml l-1)
Skipjack 50 1.87
75 2.16
Yellowfin 50 1.14
75 1.77
Bigeye 50 0.40
75 0.50
Albacore 50 1.23
75 1.03
Less tolerant to low values
Most tolerant to low values
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Ocean Productivity
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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.

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Integrated approach
Modeling the interaction of oceanic variables
with tuna biology and population
dynamics SEAPODYM Spatial Ecosystem And
Populations Dynamics Model
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Integrated approach
1- Predict observed variability
2 Project Climate Change impact
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Integrated approach
Bigeye
Skipjack
2000
2000
Larvae density
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.
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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
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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 150W 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.
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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.
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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.
Skipjack reanalysis at 2x month
1 yr average

• New IPCC AR5 simulations
• Downscaling techniques