Monitoring Impacts of Climate
Change on Oceanic Fisheries
(Filling Important Information Gaps)
John Hampton
Oceanic Fisheries Programme, SPC
Monitoring Climate Change in Oceanic
Fisheries
1. Impacts on target species (tunas)
– E.g., recruitment, natural mortality, growth,
movement, reproduction
2. Impacts on the underlying ecosystem
– Pelagic food web, trophic structure, biodiversity
3. Impacts on the fisheries
– Distribution and performance (CPUE), size
composition, species composition
– Subject of ongoing programmes of data collection and
stock assessment
1. Impacts on Tuna
• SEAPODYM model is a model of high spatial resolution,
that may be suitable as a monitoring and forecasting tool
– Can assimilate environmental, biological and fisheries data in
near-real time
High-resolution modelling of
skipjack population, with catches
(circles) overlain
– With a good understanding of the way that ocean environment
interacts with tuna biology, we can predict responses of tuna
stocks and fisheries through simulations forced by climate
change model scenarios
Early Results of Simulations
Skipjack
Bigeye
SEAPODYM-Based CC Modelling
• Phase 1 (1 year, in progress, funded by Aus DCCEE)
– Revise skipjack and bigeye simulations using new forcing
data
– Extend to yellowfin and South Pacific albacore
– Run simulations for A2 and B1 scenarios
• Phase 2 (3 years, funding being sought)
– Further develop simulations, e.g. to include effects of
ocean acidity
– Apply a ‘plausible ensemble’ of IPCC-class simulations to
bound uncertainty in tuna responses
– Sub-regional/national applications using down-sized data
Future Climate Change Impacts
• Use the SEAPODYM framework to monitor in
near-real-time, and to predict into the future
• The reliability of model estimates dependent on:
–
–
–
Accurate high-resolution output of models of
physical/biological oceanography conditioned on/validated by
extensive observations
Accurate high-resolution fisheries data (collected as part of the
regular OFP fishery monitoring work programme)
Fishery-independent data that are directly informative on the
processes liable to be subject to change – movements, natural
mortality, growth
Tuna Tagging
• Tuna tagging can provide direct data on tuna
biological process for use in CC monitoring and
prediction
Bigeye Tuna
Skipjack Tuna
CC Monitoring Proposal 1
• Regular (annual) structured tagging surveys to monitor
dynamic processes (movement, growth, etc) likely to be
impacted by CC
• Surveys would provide empirical indicators of change
• Data assimilated into SEAPODYM models would enhance
predictive capabilities
• Currently have funding (USD 3 million) for 3 x 3 month
annual tag release cruises in PNG
• Additional funding to extend that work into other areas of
the Western and Central Pacific
2. Changes in the Underlying Ecosystem
• Climate change impacts on target tuna species are
fairly readily observable
• However, changes at lower trophic levels may also
occur, and if observable, could provide an “early
warning system” for pending large-scale changes
in the tropical pelagic ecosystem
• Observing lower trophic levels (baitfish, squid,
small crustaceans, etc) directly is logistically
difficult and costly
Tuna Stomach Contents Sampling as
an Observational Window
Sampling of Top Predator Stomachs
CC Monitoring Proposal 2
• Establish baseline data set from existing data
• Design structured sampling programme utilizing
national & regional longline observer programmes
• Conduct ongoing sampling and analysis of tuna and
other top predator stomachs as a means of observing
changes in mid-trophic levels
• Incorporate these data along with catch estimates for
target species and bycatch into ecosystem models
• Potential to also consider new acoustic monitoring
data from buoys and ships of opportunity