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ICES Journal of Marine Science: Journal du Conseil 2005 62(8):1603-1608; doi:10.1016/j.icesjms.2005.07.003
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© 2005 International Council for the Exploration of the Sea

Evolution of the state of fish stocks in the Northeast Atlantic within a precautionary framework, 1970–2003: a synoptic evaluation

S.M. Garcia* and J.I. De Leiva Moreno1

FAO Fisheries Department Viale delle Terme di Caracalla, 00100 Rome, Italy

*Correspondence to S. M. Garcia: tel: +39 065 705 6467; fax: +39 065 705 3020. e-mail: serge.garcia{at}fao.org.

The state and trajectory of some of the stocks assessed by ICES in the North Atlantic in the period 1970–2003 are synoptically represented on a single system of representation of fishing mortality and biomass with precautionary reference points used as limits and thresholds. The results indicate that for nearly 30 years, the status of the stocks in relation to the precautionary reference points has been degrading in terms of spawning biomass and excess fishing mortality, driving most resources down close to and often beyond those reference points. The situation seems to have improved during the past decade, with some exceptions, as shown by progressive shift of the mean position of the stocks away from excessive mortality (since the early 1990s) and, after a time-lag, away from low biomass (since the early 2000s). The proposed representation system sticks to the reference points and value judgements used in the ICES context, but could be used with any equivalent precautionary system of representation.

Keywords: communication, fishery management, ICES, indicators, precaution

Received 11 November 2004; accepted 18 May 2005.


   Introduction
Top
 Introduction
Data and methodology
 Results
 Discussion and conclusion
 Appendix
 References
 
A first version of the present document, using data released in 1999 by the ICES Advisory Committee on Fishery Management (ACFM; ICES, 1999), was presented at the CWP Intersessional Working Group on Precautionary Approach Terminology (Garcia and De Leiva Moreno, 2000). The purpose was to offer a simple approach to represent synoptically, in time and space, the state of some ICES stocks, across many years, on a single reference system. Selected results of a more complete analysis were also presented at the 2001 Iceland—FAO Conference on Responsible Fisheries in the Marine Ecosystem (Garcia and De Leiva Moreno, 2003). The present version updates the former representation using the data released by ACFM in October 2004 (ICES, 2004), and covers the period 1970–2003.

The Precautionary Approach to Fisheries (PAF) promoted by FAO (FAO, 1995; Garcia, 1996) is still in its first phase of implementation in most advanced regional fishery management organizations (Garcia, 2000). ICES undertakes recurrent assessments of the state of the stocks under their jurisdiction and provides scientific advice for their management, following the PAF. The ACFM report now provides routinely a "precautionary plot" describing the chronological trajectory of separate stocks/fisheries within a bivariate system of reference with one or two indicators (fishing mortality and/or spawning-stock biomass), with their limit and threshold reference values or reference points (e.g. ICES, 1997, p. 15). As the trajectories can be complicated, simplified interpretation of an ICES precautionary plot is given in Figure 1. Flim and Blim mean, respectively, the maximum fishing mortality and minimum biomass limits acceptable. Fpa and Bpa (where "pa" stands for precautionary approach) are threshold reference points. These reference points, defined in various ways for different stocks during the assessment process, establish a "safe zone2" to which fisheries management aims in the long term, a precautionary "buffer zone" which should be avoided as far as possible, and a high-risk zone in which there is either overfishing (i.e. fishing mortality is above the established limit reference point Flim), or the stock has been overfished (i.e. the biomass is below the established limit reference point Blim) and is at risk of serious or irreversible harm.


Figure 1
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  		Figure 1 Schematic representation of an ICES/ACFM precautionary plot.

 
This representation, which is indeed a simple bivariate sustainability indicator framework, is quite similar to the sustainability barometer proposed by Prescot-Allen (1997), with fishing mortality as indicator of pressure and biomass as indicator of state. In general, reference points should reflect objectives and constraints and have implications in terms of action to be taken. Considering simultaneously the two criteria (F and B), the ICES limit and threshold reference points, and following the representation principles established for the sustainability barometer (Prescot-Allen, 1997), Figure 1 can be interpreted as below.
  1. When both F and B appear to be better than the precautionary levels (Fpa and Bpa), the situation is fully satisfactory in terms of sustainability, and the fishery is in the long-term safe zone. Fishing levels should be stabilized and eventually adjusted to short-term (decadal) stock oscillations. Biomass could be further rebuilt to some higher target level corresponding to a higher likelihood of providing new desired social and economic benefits. Obviously, the farther the stock is from the threshold reference point, the smaller the risk is for the resource.
  2. When both F and B levels are between the threshold and limit reference points (in the buffer zone), the risk of recruitment failure is already fairly high, particularly under unfavourable climatic conditions, and this risk increases rapidly as stock status moves closer to the limits. The situation is not precautionary, and corrective measures are needed for reducing harvest rates (when fishing mortality is above Fpa), for long-term stock rebuilding (when biomass is below Bpa) as appropriate, and to adjust the course of action to the socio-economic capacity of the sector to absorb their cost.
  3. When either F or B is beyond the acceptable limit (Flim and Blim), the situation is considered highly unsatisfactory (unsafe zone). Either excessive fishing mortality is being applied (overfishing is ongoing), although B might not yet be below its limit, or the biomass is much too low (the stock has been overfished and possibly depleted), although F might have been reduced subsequently. More urgent corrective actions than above are needed to reduce capacity and to rebuild stocks as a priority.
  4. When both F and B are beyond the limit, the stock is being continuously depleted despite its biomass being critically low (also part of the unsafe zone). The stocks are considered as running an unacceptably high risk of recruitment failure even under average environmental conditions. In the presence of large climate-driven oscillations, a short series of poor climatic conditions could drive the stock and the fishery to collapse. The situation would call for immediate corrective action aimed at conservation, and such action may include a temporary moratorium.

The above system is used in ICES (and NAFO) to describe the historical evolution of single stocks/fisheries. However, the fishery sector as a whole tends to operate as a system at a macro-level, with transfers of capacity between fisheries, depending on profitability and operational opportunities. In addition, the ecosystem approach to fisheries (EAF; Garcia et al., 2003) imposes, inter alia, a wish to assess and manage fishery resources in a global and multispecies perspective. It would, therefore, be useful to have a single system of representation: (1) the diagnostic regarding all the exploited stocks in an area, or large ecosystem, for a given year; (2) the historical trajectory of that stock/fishery assemblage across time. The problem is that the absolute values of F and B, and the degree of precaution required (i.e. the width of the buffer zone), differ substantially between stocks, requiring some form of normalization of the data for their synoptic representation. A possible normalization approach is described below.


   Data and methodology
Top
 Introduction
 Data and methodology
Results
 Discussion and conclusion
 Appendix
 References
 
Garcia (1996) and Garcia and Staples (2000) suggested that when data on F and B are available for many stocks, their synoptic representation on a single biplot was possible by using as indicators the ratio between the variable and the reference value (e.g. F/Flim or B/Blim). However, the normalization problem becomes more complex when two sets of reference points are used simultaneously for each indicator: a set of limits (Flim, Blim) and a set of thresholds (Fpa or Bpa). We propose overcoming the difficulty by normalizing the indicators (Fnorm or Bnorm) as follows: (i) rescale every pair of values (F, B) for a given stock in a given year by reference to their respective limits (F–Flim) and (B–Blim); (ii) recast the rescaled values in standard buffer units, dividing them by the buffer width (i.e. the absolute value of (Fpa – Flim) and (Bpa – Blim), respectively).

It should be stressed that the resulting normalized fishing mortality and stock biomass indices are no longer proportional to B and F, and indicate instead the distance to the lower allowable limits (Flim and Blim) relative to the buffer range, i.e. the relative importance of the safety cushion. As such, they reflect the relative safety of the situation in which the respective stocks and fisheries lie with respect to the precautionary reference values adopted for them. Identical values of Fnorm or Bnorm for different fisheries may reflect the same degree of relative safety only if the original sets of reference values also did. The rescaling allows all the stocks for which information is available to be represented on a single precautionary graph for a given year, as in Figure 2, giving an annual synoptic snapshot of the situation. In addition, the proportion of the total number of stocks falling in the safe, buffer, and unsafe zones could be calculated, giving a convenient annual synoptic summary (see Results).


Figure 2
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  		Figure 2 Synoptic normalized representation of the state of selected ICES stocks in 1970. Triangles indicate data points out of range (see text).

 
It is also convenient to represent annually the overall historical trajectory of all ICES stocks in a single graph, as a representation of the overall management performance. Superimposing the annual scatterplots elaborated above for a series of years would indeed illustrate the dynamics of the situation across time, but the figure would be extremely difficult to read. Two ways of improving the representation are therefore proposed: (i) for each year, the proportion of stocks falling in the safe, buffer, and unsafe zones shown in Figure 1 are calculated and plotted against time; (ii) all stocks and all years are plotted on one precautionary graph, reducing each scatterplot to its centre of gravity, simply calculated as the arithmetic mean of the normalized Fnorm and Bnorm values, after having checked that the means and medians were roughly similar.

The data used are those in the latest ACFM report available to us (ICES, 2004); they cover the period 1970–2003. The number of stocks for which the required information (Fpa, Flim, Bpa, and Blim) is available has varied between 10 and 14, depending on year (see Appendix).


   Results
Top
 Introduction
 Data and methodology
 Results
Discussion and conclusion
 Appendix
 References
 
The results obtained for 1970 (on 10 stocks) are shown in Figure 2. Some data points are represented by isosceles triangles to indicate that they are out of scale, the base of the triangle giving the position of the stock in relation to the reference indicator (i.e. B on Figure 2), and its apex indicating the direction in which the stock stands out of scale. As early as in 1970, few stocks (3 of 10) were at the edge of the safe zone, few in the overfishing area (2 of 10), and most in the buffer zone (5 of 10). Bnorm was, however, above the threshold level for all stocks but two.

The results obtained for 1970, 1980, 1990, 2000, and 2003 are shown in Figure 3. There is a trend for the scatterplot to extend towards and beyond Flim and Blim, i.e. towards the high-risk areas, at least until 1990–2000, with a hint of reversal between 2000 and 2003.


Figure 3
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  		Figure 3 Synoptic normalized representation of the state of ICES stocks for different years.

 
When the entire sequence of annual scatterplots from 1970 to 2003 (not shown here for lack of space) is considered, the overall picture is somewhat blurred because of interannual variability, but this general trend is confirmed and detailed. The shift towards higher Fnorm levels, close to or beyond Flim, appears to take place until the late 1980s. Then, in the early 1990s, a reverse shift towards lower Fnorm levels (i.e. towards the buffer zone) starts, although Bnorm continues to decrease, with a larger proportion of stocks with a Bnorm below the precautionary levels being observed at the end of the 1990s. After 2000, there appears to be an improvement in the number of stocks over Bpa (only one stock in 2000, seven stocks in 2003). This might indicate that, as might be expected, a time-lag between the trend in reduction of Fnorm and the positive response of Bnorm. The experts behind the individual assessments might find other possible explanations, but for the stocks considered here and with the information to hand, a real improvement seems likely.

The trend is more clearly seen in Figure 4, which shows the proportion of stocks in the safe, unsafe, and buffer zones. Despite some noise in the Figure, the number of stocks in an unsafe state clearly increased from 1970 to 1990, and there was a corresponding decrease in the number of stocks in a safe state, though the situation improved after 1990.


Figure 4
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  		Figure 4 Evolution of the proportion of ICES stocks falling in the safe, buffer, and unsafe zones, 1970–2003.

 
The evolution between 1970 and 2003 can also be represented in a precautionary plot by summarizing each annual scatterplot by its centre of gravity, calculated as the simple arithmetic mean of Fnorm and Bnorm (Figure 5). For nearly 30 years, though with oscillations, the stocks' Bnorm (i.e. their biomass safety cushion) has been progressively depressed close to the precautionary level, and even below that. It also shows a simultaneous increase of Fnorm towards the limit level, and even beyond it. After 2000, Fnorm appears to decrease, and Bnorm correspondingly to improve. Examination of the separate trends in Fnorm and Bnorm (Figure 6) confirms this evolution.


Figure 6
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  		Figure 6 Trends in Bnorm (dotted line) and Fnorm (continuous line) from 1970 to 2003, with polynomial fits.

 


Figure 5
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  		Figure 5 Trajectory of the centre of gravity of ICES stocks, 1970–2003. The main trend (thick line) is drawn by hand.

 

   Discussion and conclusion
Top
 Introduction
 Data and methodology
 Results
 Discussion and conclusion
Appendix
 References
 
Using a graphical approach, a synoptic representation of sustainability indicators has here been developed to summarize simplistically the state of stocks in the ICES area between 1970 and 2003. In that respect, a number of issues need to be stressed.
  1. Representing many stocks across many years synoptically allows development of an overview of the medium- to long-term evolution of a mix of resources and fisheries in an entire area, reflecting the performance of governance of the sector as a whole. Such assessment can be a useful complement to the assessment of management performance in a particular fishery. Re-labelling the axes in a more reader-friendly way, such representations would also facilitate transmission of large amounts of complex information to a non-technical audience.
  2. The conclusions of this paper serve to illustrate just one of the types of representation one might select and the conclusion that might be reached. Other representations might be possible, but it is hard to imagine that they could lead to different conclusions.
  3. The values adopted by ICES as limits and thresholds have been considered as the best scientific information available, and no inference is made as to the real level of precaution (or protection) against potential negative events they may offer.
  4. We have used the "pa" and "lim" values as provided in the ACFM reports. Not having detailed understanding of the way in which these reference values are established for each stock, we do not know if they have exactly the same significance for all stocks and, for instance, whether the buffer range represents the same degree of precaution in each case. In this paper, therefore, we do not pretend to show how precautionary the management system is, but rather how it apparently performs in relation to the precautionary system of reference that applies, whatever the properties of that system might be.
  5. The number of points grouped on a single figure is very much dependent on the data available for each stock. Only 10–14 stocks, of about 135 stocks of fish and shellfish evaluated by ACFM every year, had information on both threshold and limit levels. If we had limited the analysis to just one of these levels, a much larger number of data points could have been represented. As a consequence, the extent to which the conclusions reached for this subset of stocks can be generalized to the whole region and resources depends on the degree to which the limited set of stocks selected is representative of the whole set evaluated by ACFM.
  6. In calculating the centre of gravity of each annual scatterplot, the data points have not been weighted in any way. Weighting them, for example according to stock potential (e.g. by some long-term average maximal yield or value), could be done if a particular perspective was required.

The potential benefits of harmonizing the definition of precautionary reference points between countries and organizations sharing resources at national, regional, ecosystem, or global levels should be clear. NAFO, for instance, uses a PAF very similar in principle, but different in the definitions of its reference points (NAFO, 2003). A particular constraint in the elaboration of chronological analyses is in the possible changes in reference points across time. In NAFO, for instance, the approach proposed by its Scientific Council (though never formally adopted by the Commission) evolved between 1997 and 2003 (NAFO, 2003). The changes introduced more flexibility in the course of action triggered by the parameters of stock status, and increased the negotiation space and hence the role of socio-economic or political considerations. These changes seem to have de facto reduced the theoretical rigidity and degree of protection offered to stocks, but might perhaps improve fishers' support for the approach and its actual degree of implementation. Keeping Fmsy as the formal upper limit to fishing mortality, the NAFO precautionary framework appears more cautious than the ICES framework, more in line with the 1995 UN Fish Stock Agreement requirements which, in its Annex II, Article 7, clearly establish Fmsy as the minimum international standard for fishing mortality limit reference points and Bmsy as a stock-rebuilding target for overfished stocks.


   Appendix
Top
 Introduction
 Data and methodology
 Results
 Discussion and conclusion
 Appendix
References
 
List of the stocks for which Fpa, Flim, Bpa, and Blim were defined in the 2004 Report of the ICES Advisory Committee on Fishery Management and Advisory Committee on Ecosystems:

  1. Cod in Subareas I and II;
  2. Cod in Subarea IV (North Sea), Division VIId (Eastern English Channel), and Division IIIa (Skagerrak);
  3. Cod in Division VIIa (Irish Sea);
  4. Cod in Divisions VIIe–k;
  5. Haddock in Subareas I and II;
  6. Haddock in Subarea IV (North Sea) and Division IIIa;
  7. Hake: northern stock (Division IIIa, Subareas IV, VI, and VII, and Divisions VIIIa,b);
  8. Hake: southern stock (Divisions VIIIc and IXa);
  9. Plaice in Subarea IV (North Sea);
  10. Plaice in Division VIId (Eastern English Channel);
  11. Saithe in Subareas I and II;
  12. Saithe in Subarea IV (North Sea), Division IIIa (Skagerrak), and Subarea VI (west of Scotland and Rockall);
  13. Sole in Division VIIa (Irish Sea);
  14. Sole in Division VIIe (Western English Channel).


   Acknowledgements
 
The anonymous reviewers whose help in focussing our ideas and this manuscript through useful comments and suggestions, and clarifying in particular ICES understanding behind the precautionary plots, is gratefully acknowledged.


   Footnotes
 
1 The views expressed are those of the authors and may not reflect the position of FAO. Back

2 Or a viable zone within which specific annual or multi-annual targets may be identified. Back


   References
Top
 Introduction
 Data and methodology
 Results
 Discussion and conclusion
 Appendix
 References
 

    FAO. (1995) Precautionary approach to fisheries. 1. Guidelines on the precautionary approach to capture fisheries and species introductions. FAO Fisheries Technical Paper, 350, Part 1. 52 pp.

    FAO. Precautionary approach to fisheries. Part 2. Scientific papers Garcia S. M. (1996) The precautionary approach to fisheries and its implications for fishery research, technology and management: an updated review. FAO Fisheries Technical Paper, 350, Part 2. 1–75.

    Garcia S.M. (2000) The Precautionary Approach to Fisheries: Progress Review and Main Issues: 1995–2000. Current Maritime Issues and the Food and Agricultural Organization of the United NationsMartinus Nijhoff Publications pp. 479–560. University of Virginia, Center for Oceans Law and Policy.

    Garcia S. M. and De Leiva Moreno J. I. (2000) Proposal for a synoptic presentation of state of stock and management advice in a precautionary indicators framework perspective. Report of the CWP Inter-sessional Working Group on Precautionary Approach Terminology14–16 February 2000Copenhagen, Denmark pp. pp. 49–53 (http://www.ices.dk/reports/acfm/2000/cwp/cwp00.pdf).

    Garcia S.M. and De Leiva Moreno J.I. (2003) Global overview of marine fisheries. In Sinclair M. and Valdimarsson G. (Eds.). Responsible Fisheries in the Marine EcosystemFAO and CABI Publishing pp. 1–24.

    Garcia S.M. and Staples D. (2000) Sustainability reference systems and indicators for responsible marine capture fisheries: a review of concepts and elements for a set of guidelines. Marine Fisheries Research 51:385–426.

    Garcia S. M., Zerbi A., Aliaume C., Do Chi T., Lasserre G. (2003) The ecosystem approach to fisheries. Issues, terminology, principles, institutional foundations, implementation and outlook. FAO Fisheries Technical Paper, 443. 71 pp.

    ICES. (1997) Report of the Study Group on the Precautionary Approach to Fisheries Management5–11 February 1997Copenhagen ICES Document, CM 1997/Assess: 7. 41 pp.

    ICES. (1999) Extract of the Report of the ICES Advisory Committee on Fishery Management, October 1999. ICES, Copenhagen. Multiple pages.

    ICES. (2004) Report of the ICES Advisory Committee on Fishery Management and Advisory Committee on Ecosystems, 2004. ICES Advice 1:Number 2 1544 pp.

    NAFO. (2003) Proposed NAFO Precautionary Approach Framework from Scientific Council. NAFO SCS Document, 03/23, Serial No. N4900. 5 pp.

    Prescot-Allen R. (1997) Barometer of Sustainability: What Its for and How to Use It(The World Conservation Union (IUCN), Gland, Switzerland) 25 pp.


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