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

2. Goal Capacity Building via Staff Exchange But
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
Goal

3. 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

4. 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
At minimum, a quantitative stock assessment requires monitoring of catch, abundance, and biological characteristics of the stock. These three primary sources of data feed into mathematical models that represent the demographics of the harvested fish stock and produce estimates of relevant fishery management factors. Information on ecosystem and environmental effects is incorporated into the models, when possible, to improve the interpretation of historical information and the precision of forecasts.
Stock Status

5. 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, 6:1-20)

6. 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 > Equilibrium Reduces Biomass
Maximum
Sustainable Yield
(MSY)
CATCH
Equilibrium
Yield
Curve
Catch < Equilibrium
Allows Growth K
STOCK BIOMASS

7. 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)

8. Effects of an Environmental Shift
Favorable
Environment
MSY
Unfavorable
Environment
Conceptual model for artificial reef enhancement: Substitute habitat for environment

9. Incorporating Environmental Signals into Forecasts of Future Recruitment and Catch

10. 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

11. Thank You