Overview of Risk Policy and Managing for Uncertainty Across the Regional Fishery Management Councils

Transcription

1 Overview of Risk Policy and Managing for Uncertainty Across the Regional Fishery Management Councils

2 Overview of Risk Policies Councils, in general, have adopted a risk policies based mainly on the level of scientific uncertainty and the risk of overfishing, and not based on a combination of uncertainty and economic and social impacts. For majority of Councils, risk policy comprises of the factors taken into account for scientific uncertainty and encompasses the approach for ABC CRs, which implicitly reflects the level of risk tolerance for overfishing a stock. These policies range from a p* approach to determining OFL to setting a fixed buffer below OFL or include ad hoc, qualitative approaches to managing risk. P* method requires that an estimates of MSY and some measure of statistical uncertainty about the OFL be available, so it only works for assessed stocks.

3 MAFMC Risk Policy Specifies an explicit risk policy defined in terms of an acceptable probability (p*) that a catch equal to the ABC would result in overfishing for data rich stocks. Plots the current biomass to biomass associated with MSY (B/B MSY ) ratio on the x-axis and the p* options on the y-axis Based on a linear reduction in probability of overfishing, which translates into a reduction in fishing mortality (F). Employs a default maximum p* value of 0.40 for typical stocks with a B/B MSY ratio of 1.0 or greater. A maximum p* value of 0.35 is used for atypical stocks more vulnerable to overfishing (SSC decides). For stocks without an F MSY estimate or proxy, catch levels cannot be increased without SSC recommendation. However, most of the MAFMC stocks do not have the required data for a p* approach to be implemented at this time.

4 SAFMC Risk Policy Utilizes a tiered-approach that employs p* and a decision tree that allow the SSC and Council to decide on scalar reductions to set buffers from OFLs to ABCs. SSC estimates a critical probability value, based on data and assessment information availability, characterization of uncertainty, stock status, and Productivity Susceptibility Analysis (PSA) for each stock. Estimates the downward reduction in the maximum p* value from 0.50 using the last step. The council then selects its preferred p*, which can be set equal to or below the revised maximum p* value. In 2013, the SSC applied the approved ABC control rule to black sea bass, revised P* to be 40% (Regulatory amendment 19).

5 Decision Tree: An example from SAFMC Level 1: Assessed Stocks (Each criteria can be scored a maximum 10% and then total score is deducted from a P* of Assessment Information: Five criteria ranging from quantitative assessment of exploitation and biomass to reliable catch history. 2. Uncertainty Characterization: Ranges from high to none. 3. Stock Status: Ranges from neither overfished nor overfishing to overfishes or status unknown. 4. Productivity and Susceptibility: Ranges from low to High Risk. Level 2 - Unassessed Stocks. Reliable landings and life history information available OFL derived from "Depletion-Based Stock Reduction Analysis" (DBSRA). ABC derived from applying the assessed stocks rule to determine adjustment factor if possible, or from expert judgment if not possible. Level 3 - Unassessed Stocks. Inadequate data to support DBSRA ABC derived directly, from "Depletion-Corrected Average Catch" (DCAC). Done when only a limited number of years of catch data for a fishery are available. Requires a higher level of informed expert judgment than Level 2. Level 4 - Unassessed Stocks. Inadequate data to support DCAC or DBSRA OFL and ABC derived on a case-by-case basis. ORCS ad hoc group is currently working on what to do when not enough data exist to perform DCAC.

6 GMFMC and WPFMC Risk Policies GMFMC: Similar to the approach by SAFMC, GMFMC with advice from the SSC sets an acceptable level of risk (P*) using a risk determination table and a tiered approach that calculates a P* based on the level of information and uncertainty in the stock assessment. For data rich stocks, the P* values range from 30% to 50% to accommodate different stocks. Council is recently considering to expand P* values in top tier from 30%-50% to 1%-50%. WPFMC: Similar to SAFMC, developed scoring system and established categories within each dimension. The P* Working Group uses scores for each dimension that reflects risk (max.10). The summed score is subtracted from the P*MAX of 50% OFL, or a maximum of 50% risk of overfishing, to determine the P*.

7 Risk Policy of Other Councils The NPFMC incorporates either a probabilistic (p*) approach or a fixed buffer below the OFL for both groundfish plans and the crab plan, and a fixed buffer approach for scallops. The SSC can further adjust buffers to account for additional unquantifiable uncertainty and create Council options for additional buffers from OFLs to ABCs. The Pacific Council specifies a P* based on SSC input for data rich stocks with a maximum value 0.45 and chooses a straight reduction from OFL data poor stocks. The CFMC sets ACLSs using a multi-step process. The OFL can be set to the average or median of annual catch for a specified period in the absence of a stock assessment and will equal an MSY proxy. Defining the ABC could entail using a buffer from the OFL that represents an acceptable level of risk due to scientific uncertainty or setting the ABC equal to OFL. The buffer is predetermined for each stock or stock complex by the Council with advice from the SSC.

8 Socio-economic and Ecological Considerations NPFMC: Consider tradeoffs of foregone yield in terms of discounted revenues and net present values in setting annual ABCs for crab. Uses annual Ecosystem Considerations Report for a more holistic approach. PFMC: Explicitly consider social and economic input during ACL specification for the Deep Seven complex. Established a Social, Economic, Ecological, and Management (SEEM) Working Group to evaluate region-specific considerations of specifying ACTs lower than ACLs. GMFMC: Socioeconomic Committee provides analysis on economic and social impacts of potential ACT decisions. WPFMC: Conducts SEEM analysis which includes social, economic, ecological factors and the management uncertainty in determining ACLs. Like the P* qualitative construct, the scores for each dimension will be added together so that the total score is subtracted from a default value of 100% ABC.

9 Scientific Uncertainty and ABC Control Rules Scientific uncertainty is taken into account in the specification of ABCs and application of ABC Control Rules Control rules are also a function of Council s risk tolerance The ABC control rules vary across council regions and across stocks/tiers.

10 Sources of Scientific Uncertainty Data limitations, observation error, uncertainty associated with the landings data due to underreporting or non-reporting. Variability in biomass estimates across assessments, retrospective patterns in the assessments Within-model uncertainty, measures of parameter estimation uncertainty, estimation errors for catchability quotient (q) Explicit recruitment uncertainty, changes in productivity

11 Sources of Scientific Uncertainty by Council Council Sources of Scientific Uncertainty North Pacific Management Council (NPFMC) Pacific Fishery Management Council (PFMC) Western Pacific Fishery Management Council (WPFMC) Gulf of Mexico Fishery Management Council (GMFMC) Caribbean Fishery Management Council (CFMC) South Atlantic Fishery Management Council (SAFMC) Mid Atlantic Fishery Management Council (MAFMC) Observation error, other 'within' assessment uncertainty sources, errors in proxy definition, estimation errors for catchability quotient (q), choices of methodology for assessments. Variability in biomass estimates across assessments, data limitation, model uncertainty, parameterization error, assessor bias. The level of information (assessment, landings and other data) available for ABC determinations. High scientific uncertainty due to large number of data poor and unassessed stocks. Type of assessment (biomass, proxies), within-model uncertainty, past performance of models, and bias of previous assessors. Uncertainty associated with the landings data due to underreporting or nonreporting. High scientific uncertainty due to lack of scientific information, catch accounting and diffuse effort across the islands. Measures of parameter estimation uncertainty, process uncertainty and explicit recruitment uncertainty. Also considers other sources of uncertainty such as different assumptions about current states of nature, different runs of the same model, etc. Scientific uncertainty from data collection, modeling and observation error, and variance of FMSY and BMSY estimates or proxies.

12 Approach to set ABCs Most councils use a tiered ABC control rule with specific procedures based on data availability and stock status. Council North Pacific Management Council (NPFMC) Pacific Fishery Management Council (PFMC) Western Pacific Fishery Management Council Gulf of Mexico Fishery Management Council Caribbean Fishery Management Council (CFMC) South Atlantic Fishery Management Council Mid Atlantic Fishery Management Council (MAFMC) Tiered system Six Tiers Three tiers Five Tiers (South Atlantic Model) Three tiers (South Atlantic Model) Eight scenarios Four Tiers Four level strategy

13 ABC Control Rules Control rules vary by tiers For data rich tiers -- P* approach For data poor stocks --Fixed buffer below OFL, catch only methods, a qualitative risk based approach Some Councils have adopted a single framework for all Fishery Management Plans under which the size of the buffer between the OFL and the ABC is predetermined based on the type of assessment and quality of data used to develop biological reference points Smaller buffers are set for assessed stocks including statistical estimates of uncertainty and larger buffers are set for data poor stocks. Other Councils have set ABCs using an ad-hoc approach for each fishery or stock, although the same sources of uncertainty are considered in setting ABC buffers. The ad-hoc approach allows more flexibility while a single framework saves the SSC time that would need to be spent to evaluate each fishery or stock in much greater detail.

14 ABC Control Rules by Council Control rules vary by tiers and availability of data Council Control rules North Pacific Management Council (NPFMC) Either a p* approach or a fixed buffer below the OFL. Pacific Fishery Management Council (PFMC) Western Pacific Fishery Management Council (WPFMC) Gulf of Mexico Fishery Management Council (GMFMC) Caribbean Fishery Management Council (CFMC) South Atlantic Fishery Management Council (SAFMC) Mid Atlantic Fishery Management Council (MAFMC) Either a p* approach or a straight reduction from OFL A qualitative scoring approach to determine P* or reductions from OFL A qualitative, risk-based scoring approach to determine P*or reductions from OFL A qualitative approach to managing risk A qualitative, risk-based scoring approach to determine P*or reductions from OFL Either a P* approach (OFL distribution with CV) or expert judgment approach

15 ABC Control Rules for Data Rich Stocks (Top Tiers) NPFMC: The SSC establishes B MSY or a proxy for current biomass and calculates a Fishing Mortality rate (F) associated with the ABC, and sets a buffer to capture scientific uncertainty MAFMC: ABC is based on the distribution of the OFL and P* is based on the Council risk policy with a maximum P* of 0.40 PFMC: Council specifies a P* based on SSC input, maximum p* is 0.45 GMFMC: The Council has delegated the setting of the p* value to the SSC within a range of 0.30 to SAFMC: P* used to account for scientific uncertainty where possible WPFMC: ABC = P* percentile of the probability distribution of OFL x OFL CAFMC: Mostly data poor stocks, no top tiers

16 ABC Control Rules for Data Poor Stocks NPFMC: Varies - F ABC <=F40%, F ABC = 0.75 x M, ABC = 0.75 x OFL MAFMC: 75% of FMSY to set ABC for level 4. Ad hoc approaches for level 5 stocks (e.g., adjustment to long-term catch history or survey index values) PFMC: Straight reduction from OFL GMFMC: Mean landings to 1.5 std. deviations above SAFMC: Depletion-Corrected Average Catch (DCAC) methods WPFMC: ABCs are determined based upon catch only methods CAFMC: Three buffers, OFL/ABC reduced 10% to 25% depending on overfishing ad ecological importance.

17 Continuing Challenges Data limitations and the absence of robust methods for estimating and capturing uncertainty, Prioritizing and conducting stock assessments Setting catch limits for data-poor stocks Estimating short and long-term trade-offs associated with adopting specific p* values Balancing social and economic factors with the directive to rebuild as quickly as possible. Evaluating the impact of bycatch species and ecological factors.

18 Lessons Learned MAFMC: Formalization of process for specifying ABCs created clarity in the roles of the Council and SSC. Consistent application of control rule simplifies the process However, some flexibility is needed for the Council and SSC to respond to unanticipated circumstances. GMFMC: Employing a working group was instrumental in developing the control rule and risk policy. Clearly delineating roles and responsibilities between the Council and SSC improves the development of control rule and risk policies. The ongoing discussions between the Council, SSC, and ABC Control Rule Working Group are valuable to helping the Gulf region address the challenges and refine their risk policy. NPFMC: Benefits of managing for long-term stability are not fully offset by the short-term costs of any forgone yield, so evaluation of short-term versus long-term trade-offs are necessary to make informed decisions.