Reference points for fisheries management

Table of contents

J.F. Caddy
FAO Fisheries Department and
R. Mahon
Fisheries and Environmental Consulting
Saint James, Barbados

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Food and Agriculture Organization of the United Nations Rome 1995


This document is based on a background paper on fishery management reference points prepared following a request from the Secretary of the United Nations Conference on Straddling Fish Stocks and Highly Migratory Fish Stocks after its first session in New York in June 1993, and on FAO Fisheries Circular No. 864. This document attempts to place the various reference points used, or potentially useful, for management purposes, in a broader less technical content, suitable for both assessment workers and fisheries managers.

The authors gratefully acknowledge the inputs of colleagues, notably S. Garcia, R. Grainger, J. Majkowski and U. Wijkstrom, D. Doulman, R. McGarvey and A. Rosenberg. Several of the figures were prepared by P. Lastrico and A. Bakun.


FAO Fisheries Department
FAO Regional Fishery Officers
Marine Science (General)
Directors of Fisheries

Caddy, J.F., Mahon, R.
Reference points for fisheries management.
FAO Fisheries Technical Paper. No. 347. Rome, FAO. 1995. 83p.
This paper reviews the conceptual background and application of technical reference points in fishery management. Despite considerable investment in stock assessment methodology and expertise, fisheries worldwide are overexploited. This appears to be due to a mismatch between the precision of assessment and the precision of management. Two types of reference points are recognized: target reference points (TRPs) and limit reference points (LRPs). The use of MSY as a target reference point is considered in the light of past performance of fishery management, and it is suggested that MSY and other reference points formerly used as targets, may be more appropriately applied as LRPs. The recent trend towards the quantification of uncertainty and estimation of risk in the provision of advice is considered to be good, but the cost and availability of information and expertise required may preclude the use of these techniques for many small or low value stocks and for most stocks in developing countries. The recent trend towards inclusion of ‘ecosystem concepts’ in setting fishery management objectives is also seen as good, and overdue. Although still in their formative stages, ecosystem concepts can still provide LRPs. Effective management will require a ‘set of rules’ comprising both TRPs and LRPs. In most national and international fishery management situations, the current institutional structure will probably require some modification in order to successfully apply these sets of rules. Fisheries management organizations will continue to assess and manage fisheries routinely, but management may need to develop an independent review which comes into play when resource production limits are approached. The action to be taken at such limits should be discussed and agreed in advance.

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2.1Management objectives and the concept of a Reference Point
2.2 The underlying population models
2.3 Reference points as targets or limits
2.4 Target Reference Points (TRPs)
2.4.1 Maximum Sustainable Yield Criteria : Fmay and 2/3 Fmay
2.4.2 Yield-Per-Recruit criteria, Fmax, F0.1
2.4.3 TRPs based on the size of fish caught
2.4.4 Reference points based on the Natural Mortality Rate, M.
2.4.5 Reference points based on the total mortality rate, Zmbp, Z*
2.4.6TRPs derived from recruitment considerations
2.4.7 TRPs derived from economic considerations - the optimal fishing effort, Fmey
2.5 Limit or threshold reference points (LRPs)
2.5.1 Fmay as an LRP
2.5.2 LRPs derived from stock recruitment considerations
2.5.3 Other biological LRPs
2.5.4 LRPs derived from economic considerations
2.6 Reference points for new or developing fisheries
2.7 Reference points for stock rebuilding
2.8 ‘Precautionary’ reference points
2.9 Reference points for highly migratory resources
2.10 Multispecies and ecosystemystem considerations in setting reference points
2.10.1 Technical interactions
2.10.2 Species interactions
2.10.3Ecosystem interactions
2.11 An overview of Reference Points
3.1 Types of uncertainty
3.1.1 Uncertainty due to measurement error and bias
3.1.2 Process uncertainty
3.1.3 Model uncertainty
3.1.4 Estimation uncertainty
3.1.5 Implementation uncertainty
3.2Estimating uncertainty and risk
3.3Advising managers on uncertainty and risk
4.1 Incorporating reference points in management
4.1.1 TRPs and LRPs as ‘Sets of Rules’
4.1.2 Updating Reference Points and establishing the current status of the fishery relative to the reference point chosen
4.1.3 Components of a Reference Point-based management system
4.1.4 The role of scientific advice in Reference Point-based management
4.1.5 The use of Reference Points with different management strategies
4.2Institutional requirements
4.2.1Checks and balances from outside the fishery sector
ANNEX I:  The fishery models
ANNEX II:  Using an LRP to set a risk-averse target for exploitation - the Fmsy example
ANNEX III:   Some examples of fishery management frameworks


  1. Despite an increasingly quantitative trend in the use of reference points for fisheries management, in practice, in most jurisdictions there has been failure to conserve stocks for sustainable use. There have been several reasons for this, including:
    - poorly defined management objectives,
    - poorly defined conceptual bases for the Reference Points,
    - problems of estimating Reference Points and stock status (variability),
    - failure to link the assessment of resources to the management objectives,
    - difficulty of scientists in communicating these problems to managers and stakeholders,
    - the failure of management to constrain fisheries to agreed levels.
  2. There has been a trend in the reference points used from those which maximise yield (Fmax, Fmsy, FMsr) to lower rates of target exploitation which recognise the need to be conservative (F0.1, 2/3Fmsy) to those which set limits or thresholds to protect the stock against collapse (Fmed).
  3. The earlier reference points proposed by fishery scientists have been used primarily as Target Reference Points (TRPs), but owing to problems caused by overshooting TRPs, there has been a perceived need for reference points that help to avoid situations which are dangerous to the resource. These have been referred to as Limit Reference Points (LRPs), or threshold reference points.
  4. The shift away from Reference Points based on mathematical optima, to conservative, or protective ones that mark the boundary between rational and non-sustainable exploitation, requires decisions about what is an appropriate level of risk in the face of uncertainty due to measurement error, model error, and process error. These decisions on the acceptable risk and on the LRPs are inevitably arbitrary, but it is essential for managers to make them.
  5. The need for arbitrary, albeit technically informed, decisions has affected fishery management in two ways. The first affects the technical aspects of stock assessment, which has recently begun to focus on quantifying the effects of uncertainty on management. The second aspect affected is the decision-making process, which must develop means of evaluating and deciding upon an appropriate, or acceptable level of risk, then agreeing upon informed, even if occasionally arbitrary, target and limit reference points.
  6. The mathematical complexity of models incorporating risk, and the research costs associated with quantifying uncertainty will probably preclude this approach for most of the world's smaller fish stocks in the near future. For the managers of those stocks, the focus must be on developing the second of the options in paragraph 5, as well as focusing on procedures for agreeing upon precautionary reference points, adopting them as a convention, and taking management action in a timely and adequate fashion.
  7. There is a growing trend towards inclusion of ecosystem concepts as a basis for establishing limits to exploitation. While still immature relative to concepts based on single species considerations, these can already provide guidance as to safe limits for fishing.
  8. For limit or threshold points, the emphasis must be upon establishing agreement among participants as to the limiting conditions corresponding to the reference point(s) used and the actions to take when these are believed to have been reached. The management action should be automatic; ideally agreed to in advance by the resource users and their representatives.
  9. Most national fisheries ministries and international fishery management organizations appear to be structured and to function in a way which would permit them to adopt the approach discussed above. Hitherto, these organizations may have overemphasised the role of technical inputs in making management decisions. In some cases, action has been deferred due to a lack of an adequate scientific consensus for decision.
  10. The major change which will be required by most organizations will be to incorporate a body or committee with a broader responsibility for fishery sustainability, which will be responsible for defining objectives and Reference Points, and to which management responsibility will pass when limits are approached.
  11. Given the current state of the world's fish stocks, the recent history of collapse of major fish stocks, and the continuing declining trend of many resources, there is a need to refocus effort on the agreement/decision making process, and to respect the provisions of the United Nations 1982 Convention on the Law of the Sea in taking management action based on the best available information.