Monitoring Impacts of Climate Change on Oceanic Fisheries (Filling Important Information Gaps) John Hampton Oceanic Fisheries Programme, SPC

1
Monitoring Impacts of Climate Change on Oceanic
Fisheries(Filling Important Information
Gaps)John HamptonOceanic Fisheries Programme,
SPC
2
Monitoring Climate Change in Oceanic Fisheries

• Impacts on target species (tunas)
• E.g., recruitment, natural mortality, growth,
  movement, reproduction
• Impacts on the underlying ecosystem
• Pelagic food web, trophic structure, biodiversity
• Impacts on the fisheries
• Distribution and performance (CPUE), size
  composition, species composition
• Subject of ongoing programmes of data collection
  and stock assessment

3
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

4
Early Results of Simulations
Skipjack
Bigeye
5
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

6
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

7
Tuna Tagging

• Tuna tagging can provide direct data on tuna
  biological process for use in CC monitoring and
  prediction

Bigeye Tuna
Skipjack Tuna
8
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

9
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

10
Tuna Stomach Contents Sampling as an
Observational Window
11
Sampling of Top Predator Stomachs
12
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