Stock Assessment Methodologies for Reef Systems: A Joint Analyses

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Stock Assessment Methodologies for Reef Systems
A Joint Analyses Gerard DiNardo NOAA
Fisheries, Pacific Islands Fisheries Science
Center, USAQin Chuanxin CAFS, South China Sea
Fishery Research Institute, China Hui-Hua
Lee Joint Institute for Marine and Atmospheric
Research, University of Hawaii, USA
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Goal

• Capacity Building via Staff Exchange
• Dr. Qin to PIFSC for 30 days to learn about reef
  stock assessments
• Time permitting, conduct preliminary stock
  assessments of key species in the Guangdong
  Province based on available data
• But
• Data sets are large and not easily accessible
  (still raw)
• Habitat and stock enhancement occurring
• Have to understand the extent and associated
  benefits of enhancement programs before
  conducting any assessment

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Work Plan

• Day 1-15
• Data screening, rectification and mining
• Spatiotemporal views of the data
• Exploratory analyses and literature search
• Day 16-30
• Identify analytical strategy (right tool for the
  job)
• Conduct preliminary analyses
• Initiate development of an Assessment strategy
  allowing for ecossystem enhancements

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Stock Assessment Process
Catch Logbooks, Observers, Age/Size Data
Abundance Resource Survey, Fishery CPUE, Age/Size
Data
Biology Age, Growth, Maturity
Advanced Model Habitat, Climate, Ecosystem
Population Model
Stock Status
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Conceptual population assessment model for the
annual change in biomass (B) of a harvested LMR

• Biomass additions in year T due to
• Somatic growth (G)
• Recruitment (R)
• Biomass losses in year T due to
• Fishery yield (Y)
• Natural deaths (D)

Adapted from Russell (1931. Some theoretical
considerations on the Overfishing problem.
Journal du Conseil, 61-20)
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Equilibrium, Sustainability, and Maximization

• An equilibrium stock size has an associated
  sustainable equilibrium yield
• Maximum sustainable yield (MSY) generally occurs
  at an intermediate stock size and depends on the
  harvest pattern
• MSY is the largest average yield that can
  continuously be taken from a stock under existing
  environmental conditions Ricker

Catch gt Equilibrium Reduces Biomass
Maximum Sustainable Yield (MSY)
CATCH
Equilibrium Yield Curve
Catch lt Equilibrium Allows Growth
K
STOCK BIOMASS
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Biological Reference Points

• Reference points measure the status of a fish
  stock to provide rational guidance for management
• Limit reference points express the maximum degree
  of safe exploitation
• Target reference points express the degree of
  exploitation desire by management
• MSY is the limit for USA marine fisheries and
  optimum yield is the target
• The target optimum yield is MSY as reduced by
  any relevant economic, social, or ecological
  factor
• Sustainable Fisheries Act
  (2008)

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Effects of an Environmental Shift
Favorable Environment
MSY
Unfavorable Environment
Conceptual model for artificial reef enhancement
Substitute habitat for environment
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Incorporating Environmental Signals into
Forecasts of Future Recruitment and Catch
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Requirements for Advancing Assessment(Data
Needs)

• Catch Monitoring
• CPUE Time Series
• Size Structure
• Movement (connectivity)
• Stocking numbers
• Explore utility of size-based assessment approach
  (life history information and length data)
  PIFSC-SEFSC-UM Joint Collaboration

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Thank You