1. Promotion of the FMSP Fishery Management and Stock Assessment Guides Part 2. The ‘Stock Assessment Guide’ Presented at: CRFM 2 nd Annual Science Conference Trinidad and Tobago, March 2006 By Dan Hoggarth, Scales Consulting Ltd

2. Reminder…. Two part set from project R8468: I. How to manage a fishery – A simple guide to writing a fishery management plan (the ‘Managers’ Guide’) II. A guide to fisheries stock assessment using the FMSP tools More detailed technical guide from project R8360: FAO Fisheries Technical Paper 487.FAO Fisheries Technical Paper 487. Stock assessment for Fishery Management. A framework guide to the use of the FMSP stock assessment tools. More details on stock assessments and models also available in software help files

3. The ‘SA’ Guide - Table of Contents Preface 1What is the role of stock assessment in fishery management? 2What is a stock assessment? 3What tools can I use to make a stock assessment? 4How do I select the best tool for the job? 5How should I provide stock assessment advice to managers? 6References Annexes Annex 1. A checklist for fisheries scientists Annex 2. Glossary of terms Annex 3. The analytical approach to stock assessment using LFDA and Yield Annex 2. The biomass dynamic approach to stock assessment using CEDA Annex 3. Using the ParFish tool in data-limited situations and co-management

4. 1. What is the role of Stock Assessment in fishery management? 1.1 Providing advice in the preparatory phase Identifying unit stock etcIdentifying unit stock etc 1.2 Helping develop (and review) the management plan Suggesting indicators and reference pointsSuggesting indicators and reference points Strategic advice on alternative management optionsStrategic advice on alternative management options Estimating uncertainty and advising on control rule optionsEstimating uncertainty and advising on control rule options 1.3 Fine tuning in the implementation phase Tactical advice (e.g. annually) on year-to-year adjustments in the management measuresTactical advice (e.g. annually) on year-to-year adjustments in the management measures

5. Stock assessment inputs over time Tactical Tactical assessments (short term advice) to monitor the fishery indicators and adjust management controls as needed, say every 1-2 years 200620092012 ‘07‘08‘10‘11‘13‘14 Years: Preparing for management planning (situation analysis, identify unit stock etc) strategic Full strategic assessments to develop the plan and then for reviews say every 3-5 years in future (long term advice) Sections 1.1-1.3

6. 2. What is a stock assessment? A full strategic ‘SA’ should answer three key questions: "Where would we like to be?" - the values of specific reference points selected by managers, as estimated for that fishery, updated for any new data (e.g. the actual value of F that would give MSY)."Where would we like to be?" - the values of specific reference points selected by managers, as estimated for that fishery, updated for any new data (e.g. the actual value of F that would give MSY). "Where are we now, relative to where we would like to be?" - an assessment of the current status of the fishery as given by the indicators (e.g. the estimate of F now )."Where are we now, relative to where we would like to be?" - an assessment of the current status of the fishery as given by the indicators (e.g. the estimate of F now ). "What are the implications of alternative management scenarios, including doing nothing?" - estimates of the effect on each indicator of those management measures or controls identified as feasible for the fishery."What are the implications of alternative management scenarios, including doing nothing?" - estimates of the effect on each indicator of those management measures or controls identified as feasible for the fishery.

7. What is involved in a stock assessment? NB: Full stock assessments require both indicators & reference points Intermediate parameters are only steps towards the real needs

8. Example Stock Assessment Elements Data / Inputs   Catch, effort and abundance data   Size compositions (catch at age and length frequency data)   Biological data (sex, size at maturity, etc)   Other data: Social, economic, indigenous knowledge, etc Assessment tools FMSP software   LFDA   Yield   CEDA   ParFish Other FMSPtools/guidelines   Age basedmethods   B&H invariantmethods   Multi-speciesguidelines   Bayesianapproaches   Empiricalapproaches Other tools   FiSAT   VPA   BEAM4, etc Intermediate parameters Used in models to estimate indicators and reference points, e.g.:   Individual fish growth rates (K, L ∞ )   Population growth rate (r) and carrying capacity (K)   Natural mortality (M), maturity and reproduction (L m 50 )   Gear selectivity (e.g. L c 50 ), Catchability (q)   Stock recruitment relationship Fishery Indicators   Catch, effort (C now, f now )   CPUE, Stock size (B now )   Fishing mortality rate (F now )   Others (social, economic, ecological, governance etc) Reference Points   MSY-based (F MSY, B MSY )   Proxies for MSY (e.g. F 0.1 )   For maintaining reproductive capacity (e.g. F %SSB, F %SPR )   Risk-defined (e.g. F transient )   Multispecies and eco- system based   Economic and social Management advice   Comparison of fishery indicators and reference points to provide management advice allowing for uncertainty and risk   Feedback for control rule management   Management projections (short-term and long-term advice)   Recognising multiple objectives and management options Section 2.1 (and see FAO FTP 487)

9. 2.2Are there alternative approaches to stock assessment? Yes…. Analytical / dynamic pool approach (see e.g. Annex 3 - using LFDA and Yield software) Biomass dynamic approach (see e.g. Annex 4 - using CEDA software) ParFish approach (see Annex 5) And many other alternative approaches, software, models...

10. Biomass dynamic or analytical? Biomass dynamic models like Schaefer surplus production model used in CEDA and ParFish relate fishery outputs (catch) directly to inputs (effort)relate fishery outputs (catch) directly to inputs (effort) useful where fish are hard to age – used to set quotas and effortuseful where fish are hard to age – used to set quotas and effort Analytical models used in ‘Yield’ and other ‘per recruit’ and dynamic pool approaches include intermediary processes, both biological and fishery (e.g. from LFDA)include intermediary processes, both biological and fishery (e.g. from LFDA) may be length-based or age-basedmay be length-based or age-based needed for management advice on size limits, seasons etcneeded for management advice on size limits, seasons etc Neither approach is more right or wrong than the other – they are just based on different models and assumptions Boxes 4 & 5, Table 7

11. 2.3 What data would I need? For the biomass dynamic approachFor the analytical approach Multi-year time series of catch and effort data, or catch and some other index of abundance (e.g. from annual surveys) (see Box 6) Short time series of catch composition data (e.g. from length frequencies or ageing studies) Biological data (e.g. size at maturity) (see Box 7)

12. 3. What tools can I use to make a stock assessment? FMSP software tools: Length Frequency Distribution Analysis (LFDA) see Box 8Length Frequency Distribution Analysis (LFDA) see Box 8 Yield see Box 9Yield see Box 9 Catch Effort Data Analysis (CEDA) see Box 10Catch Effort Data Analysis (CEDA) see Box 10 Participatory Fisheries Stock Assessment (ParFish) see Box 11Participatory Fisheries Stock Assessment (ParFish) see Box 11 and many others See FAO Fish. Tech. Paper 487 for details

13. 3.1 What do the different FMSP stock assessment tools estimate? (Table 5)

14. 3.2 So what type of stock assessments can I use the different tools for? Options for strategic stock assessments of the long-term effects of alternative management measures (Table 6)

15. 3.2 And for short term tactical assessments… At this stage, you just need to re-estimate your selected indicators to see if you are meeting your targets or avoiding your limits (e.g. every 1- 2 years) As shown in Table 5…... If you are using Biomass-based reference points, use CEDA or ParFishIf you are using Biomass-based reference points, use CEDA or ParFish If you are using F-based reference points, use LFDA or other (VPA)If you are using F-based reference points, use LFDA or other (VPA)

16. 4. How do I select the best tool for the job? Step 1. What tools could provide advice about the management controls and standards (indicators and reference points) selected for the fishery? See Tables 5 and 6 as above Note that several tools might be suitable, so... Step 2. Of the tools and approaches available, what is the most appropriate to the local situation? See Tables 7 and 8 to help decide See also Box 13 and Table 9 for process….

17. 5. How should I provide stock assessment advice to managers? 5.1Providing strategic advice on alternative management options 5.2Providing tactical advice to guide management by the control rules 5.3Making projections: how long will it take to achieve the results? 5.4How should I present the uncertainty in my analysis? 5.5Giving advice in terms of risk

18. 5.1 Providing strategic advice on alternative management options Remember, full strategic SA report should cover: "Where would we like to be?" - the values of specific reference points selected by managers, as estimated for that fishery, updated for any new data (e.g. the actual value of F that would give MSY, e.g. F MSY = 0.4)."Where would we like to be?" - the values of specific reference points selected by managers, as estimated for that fishery, updated for any new data (e.g. the actual value of F that would give MSY, e.g. F MSY = 0.4). "Where are we now, relative to where we would like to be?" - an assessment of the current status of the fishery as given by the indicators (e.g. the estimate of F now )."Where are we now, relative to where we would like to be?" - an assessment of the current status of the fishery as given by the indicators (e.g. the estimate of F now ). "What are the implications of alternative management scenarios, including doing nothing?" - estimates of the effect on each indicator of those management measures or controls identified as feasible for the fishery."What are the implications of alternative management scenarios, including doing nothing?" - estimates of the effect on each indicator of those management measures or controls identified as feasible for the fishery.

19. Providing strategic advice…. Use graphs or decision tables to show the trade-offs between the different objectives Graphs nice when only two objectives, e.g. here Add lines or symbols to show current position on curves SSBPR reference points, e.g. F 20%SPR, where SSBPR is 20% of its unfished level YPR reference points, e.g. F 0.1, where slope of YPR curve is 10% of that at the origin

20. Or use decision tables when more objectives to consider... E.g. here from box 14 (could add more rows or columns…)

21. 5.2 Providing tactical advice to guide management by the control rules B lim B pa Stock size this year F lim F pa Fishing mortality rate to be allowed next year e.g. mark position of F now and B now and show action required

22. 5.3 Making projections 1. Show how long it will take to achieve results 2. Allow for the fact that current biomass might be below optimum or target levels (gives the basis of rebuilding plans for overexploited fisheries). Can use Yield or CEDA software.

23. 5.4 How should I present the uncertainty in my analysis? See boxes etc to illustrate use of confidence intervals, histograms of parameter estimates, and sensitivity tests Uncertainty can be used to adjust management advice to give ‘precautionary’ reference points, but…. … remember that the manager needs to decide what level of precaution is appropriate (not the SA advisor), e.g. following discussions with stakeholders

24. Outputs from ‘Yield’ showing uncertainty in results given as histograms

25. Uncertainties in the control rule plot

26. 5.5 Giving advice in terms of risk Risk is formally defined as the probability of something bad or undesirable happening Risk assessment is one of the foundations of the precautionary approach, and required by the FAO Code of Conduct for Responsible Fisheries You can provide advice in simple ways e.g. by clarifying the risks of alternative reference pointse.g. by clarifying the risks of alternative reference points or by showing confidence intervals or distributionsor by showing confidence intervals or distributions or more explicitly e.g. using Yield’s F transient reference point (see Boxes 19 and 25)e.g. using Yield’s F transient reference point (see Boxes 19 and 25)

27. Annex 1. A checklist for fisheries scientists p 60

28. Annex 2. Glossary of terms Analytical models Bayesian approach Beverton and Holt ‘invariant’ method Biomass dynamic models Carrying Capacity CEDA Decision control rules Decision tables Depletion models Empirical models FiSAT Fishing mortality rate, F FMSP Growth overfishing Indicator Intermediate parameters LFDA Limit reference point Management measures Management strategy Management standards Mortality rates (see also fishing mortality rate) ObjectivesParFish ‘Per recruit’ indicators and ref. points Precautionary approach Precautionary reference point Production Model Projection Recruitment overfishing Reference point RiskScenario Sensitivity analysis SPR / SSBPR Stock assessment (SA) Stock assessment (SA) tools Strategic stock assessments Tactical stock assessments Target reference point Technical reference points Uncertainty Unit stock Virtual Population Analysis (VPA) von Bertalanffy growth function (VBGF) ‘Yield’

29. Annexes 3-5. Example Stock Assessment Approaches Annex 1. The analytical approach to stock assessment using LFDA and Yield Annex 2. The biomass dynamic approach to stock assessment using CEDA Annex 3. Using the ParFish tool in data-limited situations and co- management These are not complete demonstrations of the software capabilities, nor show all the options But given as examples of how a SA could be carried out, and what advice could be provided by each tool

30. The analytical stock assessment approach using LFDA and Yield LFDA Intermediate parameters L ∞, K, t 0 (growth) Z ( - M ) F now(Eq) Biological data, management controls (size limits, closed seasons etc) Compare to make management advice on F e.g. if F now > F MSY, reduce F by management controls if F now < F MSY, OK Yield Per recruit F max F 0.1 F %SPR With SRR F MSY F transient Data / inputs Assessment tools Indicators Reference points Management advice Length frequency data Annex 3

31. ‘per recruit’ or with recruitment? Including recruitment in analytical models completely changes results But stock-recruit relationship expensive to get So, if using per-recruit models, give first priority to LRPs for biomass per recruit Box 24

32. Age-based or length-based? ELEFAN, FiSAT II etc largely promoted length-based methods for tropical fisheries. FMSP LFDA software also length-based Four FMSP projects, however, have confirmed the benefits of age- based approaches, wherever fish can be aged (e.g. using otolith readings) – more accurate etc Age-based methods now used for deep slope snapper fisheries in FMSP study sites in Seychelles Length-based methods better where fish really can not be aged (e.g. crustacea), or where ageing is v. expensive Table 7

33. The CEDA stock assessment approach (biomass dynamic model) Annex 4 CEDA Intermediate parameters r, K, q B now Current catch / effort data Compare to make management advice on effort or catches Data / inputs Assessment tools Indicators Reference points Management advice Catch / effort time series B MSY f MSY MSY f now C now

34. The ParFish stock assessment approach Annex 5 ParFish Intermediate parameters r, K, q Current catch / effort data Data / inputs Assessment tools Indicators Reference points Catch / effort time series f now C now Stock assess’t interview data or other priors Preference interview data ParFish f lim C lim Management advice on effort or catch controls, in terms of limit and target levels. Targets (f opt,C opt ) incorporate the preferences of resource users. Limits are based on the risk that B will be reduced below a specified % of K. f opt C opt Management advice B now