1. Report of the Scientific and Statistical Committee
August 23, 2016

2. Major emphasis on two items
ABC Control Rule
SEDAR 46

3. Setting OFL and ABC SSC ABC Control Rule Council
Overfishing Limit (OFL): Catch expected when fishing at a level that will achieve the maximum sustainable yield (MFMT)
Catch (lbs)
Increasing
SSC ABC
Control Rule
Acceptable Biological Catch (ABC): Catch reduced below OFL to account for scientific uncertainty (catch with less than a 50% probability of exceeding the true OFL)
Annual Catch Limit (ACL): Catch that invokes accountability measures
Council
Annual Catch Target (ACT): Catch reduced below ACL to account for management uncertainty or achieve optimum yield

4. Overfished or Overfishing
Catch in Tons of a Stock
Increasing
Overfished or Overfishing
Overfishing Limit

5. ABC Control Rule: 4-Tiered System
Tier 1 – Data rich full assessment
Tier 2 – Data moderate full assessment
Tier 3 – Data limited assessment
Tier 4 – Catch only information

6. ABC Control Rule: 4-Tiered System
Multiple tiers enable the SSC and Council to establish catch limits across a wide range of data quality situations for all stocks.
This incentivizes efforts to obtain better information for data-limited stocks.
ABC buffer increases in size due to increasing uncertainty in each descending tier. In other words, the control rules is designed to be more conservative when uncertainty is higher.

7. Setting MSY, OFL, ABC
0.5
Assessment gives the distribution of OFL (probability density function = PDF)
0.4
0.3
Probability Density
Distribution of OFL
Defined by:
Mean
Variance (σ) or CV
0.2
0.1 20 40 60 80
100
120
140
160
180
200
OFL (1,000 lbs)

8. Setting MSY, OFL, ABC Where is Scientific Uncertainty? Two approaches:
50% Probability → MSY
0.5
} = Buffer: Risk of Overfishing*
ABC
0.4
*Risk of overfishing = Level of risk that the council is willing to accept that overfishing will not occur. Set by CFMC.
0.3
Where is Scientific Uncertainty?
Probability Density
0.2
Two approaches:
Variance
Buffer
0.1
MSY 20 40 60 80
100
120
140
160
180
200
OFL (1,000 lbs)

9. Setting MSY, OFL, ABC σ is a measure of uncertainty in OLF 1σ 2σ 0.5
0.4
0.3
Probability Density 1σ
0.2
0.1 2σ 20 40 60 80
100
120
140
160
180
200
OFL (1,000 lbs)

10. Setting MSY, OFL, ABC σ > σ > σ
0.5
σ is a measure of uncertainty in OLF
0.4
0.3
Probability Density
σ > σ > σ
0.2
0.1 20 40 60 80
100
120
140
160
180
200
OFL (1,000 lbs)

11. Setting MSY, OFL, ABC } = Buffer: Risk of Overfishing
50% Probability → MSY
0.5
} = Buffer: Risk of Overfishing
0.4
0.3
Probability Density
0.2
0.1
MSY
ABC 20 40 60 80
100
120
140
160
180
200
OFL (1,000 lbs)

12. Setting MSY, OFL, ABC } = Buffer: Risk of Overfishing
50% Probability → MSY
Distribution of OFL
Defined by:
Mean
Variance (σ) or CV
0.5
} = Buffer: Risk of Overfishing
0.4
0.3
Probability Density
0.2
0.1
ABC
MSY 20 40 60 80
100
120
140
160
180
200
OFL (1,000 lbs)

13. Tier 1 “Data Rich”
Condition for Use: Full stage-structured assessment where reliable time series on (1) catch, (2) stage composition and (3) index of abundance are available and the assessment provides estimates of MSST, MFMT, and PDF of OFL
Minimum Stock Size Threshold (MSST) = 0.75*SSBMSY (or proxy)
Maximum Fishing Mortality Threshold (MFMT) = FMSY (or proxy)
MFMT = FMSY ,
MSY = Long-term Yield at MFMT1
OFL = Yield at MFMT
1 Assuming the spawner-recruit relationship is well estimated, otherwise undefined.

14. Tier 1 “Data Rich”
ABC = x= OFL as reduced by scientific uncertainty† and risk of overfishing††. The reduction factor is applied to the PDF of OFL, where the PDF is determined from the assessment (where  > min ††† )
ABC*= d(x) where d =
Where:
Scalar is = 1 if risk of overfishing is specified (<0.5), <1 if not specified (=0.5)
Bcritical is defined as the minimum level of depletion at which fishing would be allowed.
†Scientific uncertainty would take into account, but not be limited to, the species life history and ecological function.
††Risk of overfishing determined by Council
††† min could be equal to coefficient of variation; min is in a log scale
Scalar if B > Bmsy
Scalar * (B-Bcritical )/ (Bmsy- Bcritical) if B < B msy

15. Setting MSY, OFL, ABC } = Buffer: Risk of Overfishing
50% Probability → MSY
0.5
} = Buffer: Risk of Overfishing
0.4
0.3
Probability Density
0.2
0.1
MSY
ABC 20 40 60 80
100
120
140
160
180
200
OFL (1,000 lbs)

16. OFL = Fmsy* B
ABC =Fmsy* B * P
Catch Level Recommendation
P = Probability of overfishing
P < 0.5
Bcritical
BMSY
Depletion level

17. Tier 2 “Data Moderate”
Condition for Use: Data-moderate approaches where two of the three time series (catch, stage composition and index of abundance) are deemed informative by the assessment process, and the assessment can provide MSST, MFMT, and PDF of OFL
Same as Tier 1, but variation of the PDF of OFL () must be greater than 1.5 min (in principle there should be more uncertainty with data-moderate approaches than data-rich approaches).

18. Tier 3 “Data Limited Quantitative Assessments”
Condition for use: Relatively data-limited or out-of-date assessments
MFMT = FMSY (or proxy such as F40%)
MSST = unknown
OFL = catch at MFMT
ABC determined from OFL as reduced by scientific uncertainty† and risk of overfishing††
Where the reduction factor is applied to the PDF of OFL when the PDF is determined from the assessment (with s > 2smin),
Where ABC = reduction factor * OFL, where reduction factor must be < 0.9
†Scientific uncertainty would take into account, but not be limited to, the species life history and ecological function, the perceived level of depletion, and vulnerability of the stock to collapse.
††Risk of overfishing determined by Council OR

19. Tier 4:
Landings & Ancillary Information (e.g. , Productivity-Susceptibility Analyses, Expert opinion) 4a
Condition for use: No accepted assessment, but stock unlikely to be subject to overfishing, and not likely to be overfished. If SSC consensus cannot be reached on the use of Tier 4a, Tier 4b should be used.
MSST, MFMT, MSY = unknown
OFL = Scalar * 75th percentile of reference period landings
Scalar =< 2 depending on perceived degree of exploitation, life history and ecological function
ABC = buffer * OFL, where buffer must be < 0.9 (e,g, 0.9, 0.8, 0.75, 0.70…)
Condition for use: No accepted assessment, but stock likely subject to overfishing and/or overfished or unclear.
MSST, MFMT, MSY = undefined
OFL = Scalar * mean of recent landings (most recent three years of available landings)
Scalar < 1 depending on perceived degree of exploitation, life history and ecological function 4b

20. OFL
Buffer = 0.9
ABC
Scalar = 1.5
75%
Mean
Median

21. Recommendations: ABC CR
The SSC recommends a workshop for on how life history parameters and ecological function would be used as input into the MSE and FMSY proxies, such as %SPR and MSY proxies and or scalar.
The SSC recommends a workshop for Council members on risk policy and proposed control rules (e.g., setting the risk of overfishing).

22. SEDAR 46 Data Limited Methods
Two Parts
Develop a Management Strategy Evaluation (MSE)
Assessing model performance relative to Performance Criteria
Apply models as a test of Data-limited Tool Kit
How do models perform across different data sets

23. Hypothetical Output of Data –limited Models
PDF of Catch for each model
Catch at Median ≈ OFL
Multiple models: Choose 1 or Combine
Model 1
Model 2
Combined Model
Density
Density
Catch Recommendation (lbs)
Catch Recommendation (lbs)

24. Species evaluated 6 species-island units 2 per island unit
Species sorted by average annual commercial landings for each island unit
Species evaluated
6 species-island units
2 per island unit
Species selection decided by SEDAR process
Designed to present a range of data quality & quantity

25. Management Strategy Evaluation
Designed to evaluate model performance
Incorporates best information (previously vetted by the data work groups) on:
Species life-history, CPUE, etc.
Expected range of variability (confidence) in the data.
Data used to simulate known population, which is then used to evaluate model performance.

26. Management Strategy Evaluation
Designed to evaluate model performance against Performance Criteria (Selected by SEDAR 46 DW/AW Panel, SSC)
PNOF: Probability of Not Overfishing (NSG1)
B50: Probability of Not Being Overfished (NSG1)
AAVY: Probability of Low Variability in Yield
LTY: Long-term Yield (Last 5 years)
STY: Short-term Yield (First 5 years)
Simulations run for 40 years
Meeting performance criteria only indicates a model is robust due to uncertainty given the model inputs (e.g., life history characteristics)

27. Management Strategy Evaluation
Example MSE Output: Model Performance relative to Simulated Population using Data based on Spiny Lobster (STT)
Performance Criteria

28. Management Strategy Evaluation
Example MSE Output: Model Performance relative to Simulated Population using Data based on Queen Triggerfish (STT)
Performance Criteria

29. Management Strategy Evaluation
Example MSE Output: Model Performance relative to Simulated Population using Data based on Stoplight Parrotfish (STT)
Performance Criteria

30. SSC Comments on SEDAR 46
The SSC commends the SEFSC on the work conducted for SEDAR 46 with respect to the scope, quantity and quality of the work performed. The SSC is excited about the MSE approach and the potential for the Data-limited Toolkit to provide management advice (i.e., OFL guidance).
The SSC finds the management strategy evaluation (MSE) to represent the best available science.

31. SSC Comments on SEDAR 46
The SSC recognizes the value of this approach for future use and has specific recommendations for improvements.
Given the time available, especially in light of important competing agenda items, the SSC felt limited in its ability to evaluate the results of SEDAR 46
SSC needed more discussion of the models that came out of the MSE
SSC needed more discussion of the rationale for making a choice between those models, where necessary.
Future presentation(s) should be provided in an oversimplified manner for context prior to full review.

32. SSC Comments on SEDAR 46
The SSC does not believe the results of the application (i.e., species assessments) can be used for management, at this time, due to couple of factors. The SSC was concerned about:
what appeared to be a discrepancy between expected performance from the MSE and the resulting catch recommendations from the application,
the differences in the magnitude of the catch recommendations from the two model classes.
An explanation describing the discrepancies was not available, and the SSC did not fully evaluate the methodology of the application.

33. SSC Comments on SEDAR 46 The SSC recommends the following:
Tune the operating model to the observations from the fishery or demonstrate why such treatment is not going to affect the application of the methods for each species (e.g., input an observed effort time-series to condition fishing mortality).
Re-evaluate the range of depletion inputs in the MSE. The SSC was particularly concerned with the range of depletion used for lobster.
To avoid confusion, methods that do not meet the performance metric criteria should not be presented
Further work on performance metrics (presentation of full distribution of all performance metrics)
More robust treatment of the indices as indicated by the CIE reviewers or demonstrate why such treatment is not going to affect the application of the methods.