IN-DEPTH STUDY: PATTERNS OF MARINE FISHERY LANDINGS AND FUTURE PROSPECTS¹

Some trends in landings
State of world marine resources
Conclusions

¹ This in-depth study has been extracted from FAO. 1996. Chronicles of marine fishery landings (1950-1994): trend analysis and fisheries potential. FAO Fisheries Technical Paper No. 359, by R.J.R. Grainger and S.M. Garcia. Rome.

The first estimates of world fishery production were provided by FAO in 1945² and these indicated that the total marine harvest was 39 billion pounds (or 17.7 million tonnes), of which 37 billion pounds was from commercial landings and the remainder from subsistence and recreational landings. Even then, one-third of the total landings were destined for reduction to fishmeal and oil. At that time only the north Pacific and north Atlantic fisheries were well developed, and these areas accounted for 47 and 46 percent of the total commercial harvest, respectively, with the southern parts of the Pacific and Atlantic oceans accounting for 1 percent each and the Indian Ocean accounting for 5 percent. The same report stated that there were considerable possibilities for fisheries expansion, mainly off Central America, Peru and Chile, in the Caribbean, off West Africa and off Australia, New Zealand, the South Pacific Islands and the East Indies. The report recognized, however, that some stocks were already overfished and pleaded that the benefits of stock recovery in European waters during the Second World War should not be lost once normal fishing activity resumed. It stressed the essential need for fisheries conservation based on scientific evidence, particularly at a regional level, and recommended that FAO promote the collection and analysis of basic fishery data.

² FAO. 1945. Five technical reports on food and agriculture: fisheries, p. 175-216. Report of the Technical Committee on Fisheries, submitted to the United Nations Interim Commission on Food and Agriculture, Washington, DC.

In the 50 years since that report was prepared, fisheries have developed rapidly with the result that there are now few underexploited resources and an increasing number of overexploited ones. The challenge of implementing effective management has proved much more difficult than the authors of the 1945 FAO report could have expected.

The first estimate of world potential production based on analysis of historical landings was made in FAO by J. Gulland in 1971.³ No other analysis of this kind has been undertaken since and, given that this analysis was based on statistics for 1953 to 1968 (less than half the time period currently available), it is appropriate to review estimates of potential in light of the major developments that have taken place since. During the period considered by Gulland, landings were increasing at about 6 percent per year (Figure 18), and Gulland estimated that the potential for traditionally exploited marine species was about 100 million tonnes per year. This estimate of fishery potential was consistent with estimates made earlier by several other authors,⁴ based on different analyses. In fact, the growth rate for marine production observed by Gulland soon fell, although some growth was maintained, and despite fisheries’ developments in non-traditional species, marine fishery production has so far reached only about 90 million tonnes, with capture fisheries accounting for 84 million tonnes.

³ Gulland, J.A., ed. 1971. The fish resources of the ocean. Fishing News (Books) Ltd. 255 pp. see also ICES. 1995. Reports of the ICES Advisory Committee on Fisheries Management, 1994. ICES Coop. Res. Rep. No. 210. International Council for the Exploration of the Sea (ICES).

⁴ Moiseev, P.A. 1971. The living resources of the world ocean, p. 203. Jerusalem, Israel Program for Scientific Translations. 334 pp.

This study presents an initial analysis of trends in marine resources as described in the FAO fishery production statistics for 1950 to 1994,⁵ during which period marine production of fish, crustaceans and molluscs grew from 18 to 90 million tonnes.

⁵ FAO. 1995. World fishery production 1950 to 1993. Supplement to the FAO Yearbook of Fishery Statistics 1993. Vol. 76. Catches and landings. Rome. 44 pp.

Some trends in landings

Relative contributions of pelagic and demersal fish

Production from marine fish species has risen from about 14 million tonnes in 1950 to about 73 million tonnes in 1994, 10 percent of which is unspecified marine fish which is usually landed unsorted and some of which goes for reduction to oil or meal. The proportion in weight of the total marine fish landings accounted for by pelagic fish has risen from about 50 percent in 1950 to over 60 percent in 1994. The production of pelagics has increased continuously, with large oscillations reflecting natural variations of resources productivity as well as boom and bust fishing strategies. In terms of value, pelagic production is less important than demersal production, but its relative importance has been increasing and in 1993 pelagic production accounted for about 40 percent of the total value of the marine fish landings compared with 50 percent for demersal fish and 10 percent for unspecified marine fish. Demersal fish production showed an increasing trend until the mid-1970s and has generally levelled off, with some oscillations, since then. The production of unspecified fish has continued to increase throughout the period considered and this represents a major shortcoming of the data set.

While 186 species items are exploited by pelagic fisheries, 50 percent of the average total pelagic landings for 1950 to 1994 are represented by only seven top species (anchoveta, Atlantic herring, Japanese pilchard, South American pilchard, chub mackerel, capelin and Chilean jack mackerel) which account for a major part of the overall variation in landings (Figure 19). A further feature shown in Figure 19 is that, once a few major and highly fluctuating species are excluded, there is a smooth and continuous increase in total landings of about 180 remaining pelagic species.

The global trend in marine demersal landings is shown in Figure 20. Once the two major species, Alaska pollock and Atlantic cod, are excluded, landings of the remaining 403 resource items show a clear pattern of increase up to the early 1970s, followed by stability since then.

An examination of the ratio of pelagic fish (small and large) to demersal fish landings from 1950 to 1994 for each ocean and the Mediterranean Sea (Figure 21) shows the following:

· In the Atlantic Ocean, pelagic fish represent on average about one-half of marine fish landings and this proportion has been extremely stable since 1954, despite the large variations in the landings of herring in the Norwegian and North seas, of sardine off Namibia and of small pelagic resources off West Africa.

· In the Pacific Ocean, pelagic fish comprise on average about 59 percent of the total landings but the proportion has fluctuated greatly, reflecting large oscillations of pelagic resources such as Peruvian anchoveta and Chilean sardine, as well as “demersal” resources such as the Alaska pollock.

· In the Mediterranean Sea, pelagic fish dominate the landings and their proportion increased steadily from the 1960s before collapsing in the late 1980s. The progression was remarkably sustained, possibly reflecting a shift in the ecosystem owing to eutrophication and the progressive depletion of predators.⁶ While nutrient enrichment might potentially benefit all fishery production by increasing productivity, it may have selectively and locally hampered the development of demersal fish stocks that were already stressed by fishing. The drop in the ratio in the 1990s reflects the collapse of the Black Sea pelagic fish resources and fisheries under environmental stress and overfishing.

⁶ Caddy, J.F., Refk, R. and Do-Chi, T. 1995. Productivity estimates for the Mediterranean: evidence of accelerating ecological change. Ocean and Coastal Management, 26(1): 1-18.

· In the Indian Ocean, pelagic fish account for less than half of all fish landings, indicating a relative deficiency of pelagic production compared with other oceans. In a recent paper,⁷ the lack of development of small pelagic fisheries development in the western Indian Ocean was noted and related to the extreme strength and turbulence of the Indian Ocean system of upwellings combined with extremely dynamic offshore advection, all factors very unfavourable to the survival of small pelagic resources.

⁷ Bakun, A, Roy, C. and Lluch-Cota, S. Coastal upwelling and other ecosystem processes controlling ecosystem productivity and fish production in the western Indian Ocean. In K. Sherman and N. Cyr, eds. Status and future of the large marine ecosystems of the Indian Ocean. Oxford, UK, Blackwell Scientific. (in press)

Figure 19. World landings of the top pelagic marine fish species and total

Demersal fisheries

It has already been noted that the underlying trend in global demersal fish production, unlike that of pelagic fish, has not shown any increase since the early 1970s. However, this masks the fact that there are regional differences in the development of fisheries and the proportions of stocks that are fully fished or overfished. Table 3 shows the sequence of dates at which peak demersal fish landings were observed in smoothed time series for each FAO region. The sequence of peaks is generally as would be expected from a knowledge of world fisheries development. Landings peaked first in the Atlantic (between the late 1960s and the early 1970s), then in the Pacific (between the mid-1970s and the late 1980s) and, finally, in the Indian Ocean (in the early 1990s). The case of the Mediterranean, one of the oldest and most intensively exploited marine systems, is a paradox as many of its resources have been declared overfished for decades although production continues to rise slowly, probably in response to eutrophication, except for in the Black Sea where pollution, species introduction and overfishing have led to a general resource and fisheries collapse.⁸

⁸ Caddy, Refk and Do-Chi, op. cit., footnote 6, p. 33.

Figure 21. Ratio between landings of pelagic and demersal fish by ocean

TABLE 3

Comparison of peak landings and recent landings (1991) for demersal fish species (five-year running means)

Fishing area	Recent landings	Maximum landings	Year of maximum landing	Recent/maximum landings
Atlantic, northwest	1 007	2 588	1967	0.39
Antarctic	28	189	1971	0.15
Atlantic, southeast	312	962	1972	0.32
Atlantic, western central	162	181	1974	0.89
Atlantic, eastern central	320	481	1974	0.67
Pacific, eastern central	76	93	1975	0.81
Atlantic, northeast	4 575	5 745	1976	0.80
Pacific, northwest	5 661	6 940	1987	0.82
Pacific, northeast	2 337	2 556	1988	0.91
Atlantic, southwest	967	1 000	1989	0.97
Pacific, southwest	498	498	1990	1.00
Pacific, southeast	459	508	1990	0.90
Mediterranean	284	284	1991	1.00
Indian, western	822	822	1991	1.00
Indian, eastern	379	379	1991	1.00
Pacific, western central	833	833	1991	1.00
Total		18 720	24 059	0.78

The final column of Table 3 shows that in two-thirds of the areas the present landings are less than the historical peak landings. In 30 percent of the areas, the landings are still increasing. Apart from the Antarctic, where resources have been explored, developed and overfished and catches have now been limited by management, the major decreases have been seen in the southeast and northwest Atlantic where landings have fallen by over 60 percent in the last two decades. Declines in other areas have been far less marked - the Pacific areas showed declines of less than 20 percent - and landings in some areas, such as the Indian Ocean and the Mediterranean, are still increasing. Although environmental changes have almost certainly played a part in some declines (e.g. in the northwest Atlantic), overfishing has been a major factor in most cases.

The difference between peak and current landings should be interpreted with caution. Peaks in smoothed production probably give an indication of the average long-term yield (ALTY) that the species assemblage in a given area may be able to produce sustainably in the future, with proper management. However, in the case of demersal stocks, which are sensitive to natural fluctuations of climatic conditions (regime shifts) on a decadal scale, peak harvests resulting from transient favourable environmental situations may bear little relation to the ALTY, although the smoothing procedure applied to the raw data should have reduced the potential impact of these problems. As a consequence, the difference between the total of peak landings and current landings (bottom line of Table 3), which amounts to about 5 million tonnes, may represent a rough estimate of the potential benefit from improved management of demersal stocks, assuming, as usual, that the stock declines are indeed reversible. In this regard, however, it is acknowledged that historical trends are also the result of environmental changes and biological interactions, and declines may sometimes reflect potentially irreversible situations created by fishing and climatic changes in the exploited ecosystem.

Overexploited marine resources

FAO prepares regular reviews of the state of world fishery resources and the one for marine fisheries⁹ classifies each of the main species fished in the major fishing areas according to its state of exploitation (unknown, underexploited, moderately exploited, fully exploited, overexploited, depleted or recovering), where this has been formally assessed. In this study all the marine resources that were classified in the FAO publication as overexploited or depleted in 1992 are considered. The aggregate landings by fishing area for all such resources (except tuna) are shown in Figure 22, and it can be seen that these stocks together showed a decline in production from over 14 million tonnes in 1985 to about 10 million tonnes in 1992 and 8 million tonnes in 1994. However, the southeast Pacific area (shown in Figure 22 as the uppermost plot component) contains only one species, the South American pilchard, which was virtually unexploited prior to 1973. Exclusion of this element shows that the decline actually started 20 years ago, with most of the decrease attributable to the northeast, northwest and southeast Atlantic areas. The pattern of long-term decline is also evident for landings of some tunas which are classified as overexploited including albacore in the Atlantic, which has shown a downward trend since the mid-1960s, and southern bluefin tuna, which has shown a more recent but steeper decline as catches have been limited by management in response to declining stock size.

⁹ FAO. 1995. Review of the state of the world fishery resources: marine fisheries. FAO Fisheries Circular, No. 884. Rome. 105 pp.

Many of the resources classified as overexploited in 1992 have thus been showing decreasing yields for the last 20 years and are now producing 6 million tonnes less than they did in 1985 and about the same as they produced in the mid-1960s, when the fishing effort was far less than it is now. The aggregate decline of 6 million tonnes in Figure 22, however, masks the successive declines in some individual resources and the compensation by increased exploitation of others. The sum of the differences between the observed historical peak landings in the (smoothed) time series of each area component and recent landings amounts to about 9 million tonnes. This observation implies that, if these individual areas could all be restored to their historical maximum levels, a gain of 9 million tonnes of landings could be expected.

Highly migratory and straddling resources

Highly migratory and straddling resources have received intense international attention at the UN Conference on Straddling Fish Stocks and Highly Migratory Fish Stocks (held in New York from 1993 to 1995) which led to the adoption of a legally binding international instrument for their improved management. Landings of highly migratory species as listed in Annex 1 of the 1982 Convention on the Law of the Sea are given in Figure 23, which shows an increase in landings from about 700 000 tonnes in 1950 to about 4.5 million tonnes in 1994. Increases have been most rapid since about 1970. In recent years, over half the total landings of highly migratory species has been accounted for by just two species - skipjack and yellowfin tunas. Skipjack is classified as underexploited or moderately exploited in the Atlantic, Indian and Pacific oceans and so it is likely that catches will increase further in the near future. In contrast, yellowfin is fully exploited in the present fishing areas of the Atlantic and Indian Oceans and in the eastern Pacific, and moderately exploited in the central and western Pacific and, unless new areas or substocks are discovered, it is unlikely that much increased catches can be sustained in the long term.

Figure 22. Landings by fishing area from all resources classified as overexploited or depleted in 1992

Figure 23. Landings from highly migratory fish resources by species

A first attempt at listing fish resources which straddle the boundary between exclusive economic zones and high seas areas was provided by FAO.¹⁰ Given constraints due to lack of geographical resolution in the landings data and to a lack of information on stock identity in many cases, it was necessary to specify these straddling “stocks” in terms of species and FAO major fishing areas. Figure 24 shows the landings of straddling resources by major fishing area since 1950.11 Overall landings of straddling stocks increased from less than 2 million tonnes in 1950 to nearly 14 million tonnes in 1989, and subsequently declined to about 12 million tonnes. The landings composition by area has changed markedly during the whole period. The northwest Atlantic provided the major part of the straddling stock landings up to the mid-1960s but the importance of the region decreased markedly as Atlantic cod stocks declined, while the northwest and northeast Pacific greatly increased their contributions, owing almost entirely to landings of Alaska pollock. Likewise, the decrease in the overall landings since 1989 is caused mainly by the reduced contribution of this latter species.

¹⁰ FAO. 1994. World review of highly migratory species and straddling stocks. FAO Fisheries Technical Paper No. 337. Rome. 70 pp.

¹¹ These resources are considered “straddling” for the whole time period concerned (1950 to 1994) for the sake of convenience and historic perspective even though many of them were high sea resources, legally speaking, before the extension of national jurisdictions, mainly after 1970.

Figure 24. Landings from straddling stocks by major fishing area

State of world marine resources

This section of the study provides an assessment of the state of world resources, by ocean and by major resource type, based on two sample models which will be briefly described. In the end of the section the results will be given.

Generalized fishery development model

The process of development of a fishery as described by changes in landings with time, often with a “boom and bust” character, has been described by many authors.¹² This process is schematically represented in Figure 25 and is composed of four phases: 1, undeveloped, 2, developing, 3, mature and 4, senescent.

¹² For example: Caddy, J.F. and Gulland, J.A. 1983. Historical patterns of fish stocks. Marine Policy, 7: 267-278; Caddy, J.F. 1984. An alternative to equilibrium theory for management of fisheries. In FAO Fisheries Report No. 289 Supplement 2. Rome. 214 pp; Welcomme, R.L. 1995. Status and trends of global inland fisheries. In N.B. Armantrout and R.J. Wolotra. Conditions of the world’s aquatic habitats. Proceedings of the World Fisheries Congress, Theme 1, p. 122-138. Oxford & IBH Publishing Co.

When a time series that is sufficiently long is available and marked changes in landings have occurred, segments of the time series may be matched to phases in the development model and so provide an indication of the historical as well as the present state of fishery development. It is important to note, however, that aggregate landings from various stocks that are the subject of a fishery complex may continue to increase despite local overfishing situations as long as the process of increase through expansion to new areas and resource elements overshadows the process of decrease through overfishing. An important implication is that the highest landings observed in a mature fishery represent a sort of multispecies composite ALTY which is different from the sum of the theoretical maximum sustainable yields (MSYs) for the various resource elements, whether these elements represent different species in a given area or even in different areas with their multispecies resource components in a given region or ocean. It must be recalled that it is not advisable to attempt to extract the MSY of any aquatic resource and that it is impossible to extract simultaneously the MSYs of all the components of a species assemblage in a given area. However, when a “meta-fishery” covers many areas, it might be possible to improve the overall ALTY by optimizing the fisheries in each area.

Figure 25 shows the theoretical change in yield and the relative rate of increase of yield during the development process. The relative rate of increase, which varies significantly as the maximum long-term yield is approached, reached and surpassed, is of particular interest and has been used here to provide a rough assessment of the state of marine resources, globally and by ocean. This rate is nil for a stable non-developing fishery (i.e. in phase 1) but increases rapidly as the fishery starts to develop (from phase 1 to phase 2). It then decreases during the phase of steady growth of the fishery (phase 2) and drops to zero again when the fishery reaches its maximum production (in phase 3). Following phase 3, fishing capacity may also develop, further aggravating depletion, and the relative rate of increase may become negative as overfishing progresses. In reality, this representation is of course obscured by natural fluctuations as well as by confusion in the data. However, the trend in decline of the relative rate of increase during phases 2 and 3 (Figure 25) is used here to estimate when full potential is reached and what the corresponding potential yield is.

State of the main resource groups

The top 200 species-area combinations used for the analysis, referred to here as “resources”, were selected for analysis on the basis of average landings over the whole time period. These 200 major resources account for 77 percent of world marine fish production; they were grouped by cluster analysis, according to the shape of the landing trends and irrespective of the scale of the landings. Table 4 summarizes the characteristics and landings trend profiles (average standardized landings with fitted curves) for four examples of the groups of resources identified by the cluster analysis (these are only four of the 12 groups used in the analysis). The profiles identified can be considered as parts of the overall fishery development model described above and reflecting some of the various phases identified (from 1 to 4, undeveloped to senescent).

The total aggregated landings (non-standardized) by cluster of resources are shown in Figure 26 together with those of the other 23 percent of marine fish landings not included in the top 200 and so excluded from the analysis (and labelled “others”). Figure 26 shows that the apparently ever-growing total marine production results from sequential development and decay of fisheries on various resource groups, for example:

· in the 1950s and 1960s, group 1n including Atlantic cod (northeast Atlantic) and Pacific jack mackerel (eastern central Pacific);

· in the 1960s, group 4p including anchoveta (southeast Pacific), Cape hakes (southeast Atlantic), haddock (northeast Atlantic), Atlantic herring, silver hake, Atlantic mackerel and American plaice (northwest Atlantic), whiting and European plaice (northeast Atlantic) and Cunene horse mackerel (southeast Atlantic);

· in the 1970s, group 2p including capelin, Atlantic mackerel, saithe, European sprat, Norway pout (northeast Atlantic), chub mackerel (northwest Pacific), southern African anchovy (southeast Atlantic), jack and horse mackerels and sardinellas (eastern central Atlantic) and Indian oil sardine (western Indian Ocean);

· in the 1980s, group 6p including Japanese pilchard, filefishes, threadsail filefish (northwest Pacific), South American pilchard (southeast Pacific), blue whiting and Atlantic redfishes (northeast Atlantic), California pilchard (eastern central Pacific), saithe (northwest Atlantic), horse mackerel and European sprat (Mediterranean);

· in the 1990s, group 1p including Chilean jack mackerel (southeast Pacific), skipjack tuna, Indian mackerels, yellowfin tuna (western central Pacific), Pacific cod, scads (northwest Pacific), Pacific cod (northeast Pacific), croakers, drums (western Indian Ocean), round sardinella (eastern central Atlantic) and skipjack tuna (western Indian Ocean).

Figure 25. Generalized fishery development model

TABLE 4

Landings trend profiles for four clustered groups of “resources” and corresponding phases of fishery development

Phases in evidence	Landings trend: average standardized landings and fitted curve	Major species in “resource” cluster*
Undeveloped (1) Developing (2)		Chilean jack mackerel Skipjack tuna Indian mackerels Yellowfin tuna Pacific cod Scads Pacific cod Croakers, drums Round sardinella Skipjack tuna	Pacific, southeast Pacific, western central. Pacific, western central Pacific, western central Pacific, northwest Pacific, northwest Pacific, northeast Indian, western Atlantic, eastern central Indian, western
Developing (2) Mature (3)		Alaska pollock Gulf menhaden Sand eels European pilchard Cape horse mackerel Argentine hake European pilchard Chub mackerel Yellowfin tuna	Pacific, northwest Pacific, northeast Atlantic, western central Atlantic, northeast Atlantic, eastern central Atlantic, southeast Atlantic, southwest Mediterranean Pacific, southeast Pacific, eastern central
Developing (2) Mature (3) Senescent (4)		Atlantic cod Pacific herring Large yellow croaker Picked dogfish Greater lizardfish Albacore Jack and horse mackerels Atlantic wolffish Southern bluefin tuna	Atlantic, northwest Pacific, northwest Pacific, northwest Atlantic, northeast Pacific, northwest Atlantic, northeast Mediterranean Atlantic, northeast Indian, eastern
Developing (2) Mature (3) Senescent (4) Developing (2)		Southern African pilchard Atlantic redfishes Yellow croaker Pacific Ocean perch Albacore East Pacific bonito European anchovy Frigate and bullet tunas Red hake	Atlantic, southeast Atlantic, northwest Pacific, northwest Pacific, northeast Pacific, northwest Pacific, southeast Atlantic, northeast Pacific, northwest Atlantic, northwest

* Only some of the major resources of each group are listed.

Figure 26. Total marine fish landing composition according to clustered groups of resources

A curve was fitted to the average standardized landings series for each group of resources. Each curve was then divided into segments corresponding to different phases of the generalized model (Figure 25) and the number of resources in each phase of fishery development calculated for each year. The overall pattern of change in the phase composition is shown in Figure 27.

Figure 27 shows strikingly the process of intensification of fisheries since 1945 and its consequences in terms of the stock of resources. It shows the large proportion of world resources that are subject to declines in productivity (phase 4, senescent) and their increase with time. It also underlines the fact that the ever-growing total tonnage of world fishery production gives a misleading vision of the state of world fishery resources and a false sense of security (a comment already made by FAO).¹³ Unfortunately, a similar comment should probably be made for changes in total aggregated landings at national level, which are often used as a justification for further development.

¹³ FAO. 1994. Current situation, trends and prospects in world capture fisheries. A paper presented by S.M. Garcia and C. Newton at the Conference on Fisheries Management: Global Trends. Seattle, Wash., USA, 14 to 16 June 1994.

The results shown for 1994 (i.e. the last data point available on Figure 27), indicate that about 35 percent of the 200 major fishery resources are senescent (i.e. showing declining yields), about 25 percent are mature (i.e. plateauing at high-exploitation levels), 40 percent are still developing and none remain at low-exploitation level (undeveloped). This indicates that around 60 percent of the major world fish resources are either mature or senescent and, given that few countries have established effective control of fishing capacity, these resources are in urgent need of management action to halt the increase in fishing capacity or to rehabilitate damaged resources. A strikingly similar conclusion was reached by FAO, which concluded that 44 percent of the stocks for which formal assessments were available were intensively to fully exploited, 16 percent were overfished, 6 percent were depleted and 3 percent were slowly recovering, concluding therefore that 69 percent of the known stocks were in need of urgent management.¹⁴ That same study, using a global production model with estimates of the world capacity, concluded that the demersal high-value species were overfished and that a reduction of at least 30 percent of fishing effort was required to rebuild the resources.

¹⁴ Ibid.

Figure 27. Percentage of major marine fish resources in various phases of fishery development

State of resources by oceans

In a review of the state of world fisheries, FAO showed that the annual relative rate of increase of world reported landings had significantly decreased since 1950, and was approaching zero, indicating that the maximum production from the world’s conventional marine resources under current exploitation regimes was being approached and that the mean catches of the last few years were probably very close to that maximum.¹⁵ The same analysis has been repeated below globally and by oceans.

¹⁵ Ibid.

Based on the analysis of total marine landings (Figure 28), the predicted maximum production for world marine fisheries with the present overall fishing regime (generally characterized by small sizes at first capture and significant discards) corresponds to about 82 million tonnes, a value close to the average landings of 1990-94 of about 83 million tonnes. It is obvious that this crude global estimate of the world potential of conventional resources under the present regime of exploitation, which indicates that the world would be at full potential about now, is a composite, aggregate result which hides the increasing occurrence of overfishing on a multitude of stocks in many different areas as evidenced during the last 50 years. In order to reduce this effect and to illustrate differences in development rates and timing, as well as potential, the analysis has been undertaken separately for each ocean.

The time series of landings for the Atlantic, Pacific and Indian oceans, as well as for the Mediterranean Sea (including the Black Sea) have been processed in the same way as the world marine total landings, and the corresponding lines showing the declines in relative rate of increase are shown in Figure 28. Only the main conclusions are reported here and details can be found elsewhere.¹⁶

¹⁶ Ibid.

Figure 28. Trends in the relative rate of increase in landings by ocean

Estimates of world marine production potential obtained from both analyses were as follows:

· estimate based on world marine total landings (potential = 82 million tonnes);

· summing estimates made for each ocean (potential = 100 million tonnes).

The aggregated estimate of 82 million tonnes refers to the present fishing regime. The difference between the aggregate potential and the sum of the different oceans’ potentials, which amounts to 18 million tonnes, is indicated to come mainly from the development of fisheries in the Indian Ocean.

In order to gain some insight in to how fishery potential might be distributed within the oceans, the same analysis was undertaken at a lower level of aggregation by considering total landings for each of 16 FAO major fishing areas. The statistical fits, which are generally much poorer than for the ocean totals, indicate an overall potential of 125 million tonnes, assuming that each area can be optimized separately. Comparing, area by area, the average landings of the last five years and the estimated potential production from this last analysis and taking into account the subjective degree of reliability of each estimate, it would appear that, compared with the present situation (i.e. landings of about 83 million tonnes):

· an increase of 10 million tonnes could well be possible (i.e. total potential of 93 million tonnes), 4 million tonnes coming from management of overfished stocks in each of the Atlantic and Pacific oceans and 2 million tonnes from fisheries development in the Indian Ocean;

· an additional increase of 17 million tonnes is less certain (i.e. total potential of 110 million tonnes), comprising 2 million and 1 million tonnes from management of overfished stocks in the Atlantic and Pacific oceans, respectively, and 14 million tonnes from development in the Pacific Ocean;

· an additional increase of 15 million tonnes is highly uncertain (i.e. total potential of 125 million tonnes), from fisheries development in the Indian Ocean.

These hypothetical potential increases, particularly the last two of 110 million and 125 million tonnes, have to be considered with prudence because some critical regional assessments (i.e. those for the Indian Ocean, the Mediterranean and the southeast Pacific) are not reliable and require further analysis to confirm or reject the preliminary results given above.

Comparison of ocean potentials

In order to investigate the coherence of the estimated potentials by ocean, a comparison of estimated potential production per unit of shelf was made for the Atlantic, Pacific and Indian oceans and for the Mediterranean and Black seas. Shelf area (between 0 and 200 m depth) and total surface area were estimated using the Geographic Information System (GIS). The relationships between ocean potential and shelf area for the two sets of data, which have been plotted on Figure 29 corresponding to estimates by ocean (potential), are surprisingly consistent although there are only four data points in each relation (the world total in each plot is not independent). This would tend to indicate that, while the results for each region have to be considered with caution, the overall picture is generally coherent.

Conclusions

Fisheries potential

The overall picture which emerges of the current state of world fisheries is consistent with what FAO has already stated in its last world review of the state of marine fisheries but, with due consideration to the numerous caveats, it differs somewhat in regard to fisheries potential.

This analysis has described the dynamics of fisheries on the 200 top marine fish resources of the world which demonstrated the rapid increase in fishing pressure. Results indicate that in 1994 about 35 percent of these resources were in the senescent phase (with declining landings), 25 percent were in the mature phase at a high level of exploitation and 40 percent were still developing, while there were none remaining in the undeveloped phase.¹⁷ A corollary of this is that there has been a gradual increase in the estimated number of stocks requiring management, from almost none in 1950 to over 60 percent in 1994. This underlines the urgent need for effective measures to control and reduce fishing capacity and effort.

¹⁷ These figures refer to “conventional” resources as no time series of data exists for the analysis of the state of non-conventional resources such as krill, mesopelagic fish and many oceanic squids which are usually considered underdeveloped.

A strikingly similar conclusion was reached by FAO in 1994¹⁸ based on traditional stock-assessment information. Using a global production model, with estimates of the world capacity as a measure of fishing pressure, it was concluded that the demersal high-value species were overfished and that a reduction of at least 30 percent of fishing effort was required to rebuild the resources.

¹⁸ FAO, op. cit., footnote 13, p. 42.

Generally speaking, the Indian Ocean has the least-developed fisheries, but the coastal resources in this ocean are under severe stress in many areas and require effective management, even though the potential for expansion may exist further offshore. It must also be pointed out that, although the possibility of expanding Indian Ocean fisheries offshore has been repeatedly considered by the coastal countries in that area (particularly India, Indonesia, Malaysia and Thailand), no convincing evidence of the existence of such resources has ever been provided.

It is interesting to note that the estimates of the possible gains to be obtained through management or development depend on the level of aggregation in the analysis. The more aggregated the data used for the analyses, the less is the estimated potential for further increase. This is an expected result as only a disaggregation of the time series by region and stock can reveal the various situations of underdevelopment or overfishing that exist contemporaneously in all areas. This analysis of regional resources takes the disaggregation only some way towards the stock level of detail.

The statements made in the various sections of this study that have implications in terms of resource assessment or fisheries outlook are summarized in Table 5. Taking all the results together, it seems reasonable to reject the assessment of world marine fishery potential based on the time series of world total landings which leads to an estimate of 82 million tonnes. The reason is that a number of more detailed analyses have shown the opposite:

· The analysis of the overexploited marine resources has shown that there may have been historical “losses” (of about 9 million tonnes) owing to overfishing which might be recouped through management. The existence of such losses is supported by the analysis of the demersal fish resources (5 million tonnes loss) and of the straddling stocks (2 million tonnes loss), although there is much overlap in the composition of these classifications. The global figure of 9 million tonnes from improvement of management of overexploited resources may be considered a minimum, assuming that the degradation of the resources is reversible.

· In addition, the resources evaluation based on the groups of resources has estimated that fisheries on 40 percent of the major marine fish resources are still developing. The analyses of the relative rate of increase in landings indicate that in 56 percent of the areas the point where the rate of increase is equal to zero has been passed, while 37 percent are still increasing. These results clearly indicate that, in some areas and on some resources, an increase in landings is still possible, even though the magnitude of this increase is not known.

Figure 29. Relationship between ocean fishery potentialand shelf area for two estimates of potential

Mariculture production is included in the data used in both the global and regional assessments. It will have a negligible influence on marine fish projections (diadromous fish such as salmon are not included in the analysis) but it is important for crustaceans and molluscs. The great variations in the importance of aquaculture among regions (which are masked in the global analysis) may explain some of the differences between the global and regional projections.

The overall conclusion from this study is, therefore, that the increase of 10 million tonnes (i.e. marine potential of 93 million tonnes) based on the more reliable estimates of potential by major fishing area seems a realistic possbility. It is entirely consistent with the possible increase in landings of 9 million tonnes from the present level through fisheries management (based on reduced landings of overexploited resources, demersal fish species and straddling stocks) plus some unknown quantities from further development (including in the Indian Ocean) from fisheries that are still developing. Given that many of the developing and declining fisheries are based on stocks that are increasing or decreasing in reponse to environmental or ecosystem changes, rather than on fishing, it is safer to reject at this stage the higher estimates of marine fishery potential.

Implications for management and development

For the resources that are at present below their historical peak levels of production it might be possible to return to those levels by reducing the fishing effort and, in most cases, simultaneously improving yield-per-recruit. This can be achieved by increasing significantly the age at first capture, prohibiting the exploitation of juveniles, increasing mesh sizes and closing temporarily or permanently areas of concentrations of young fish. Examples in Cyprus and the Philippines¹⁹ have shown that 100 percent increases of sustainable production can be obtained in the tropics within 18 months. More recent experiences with the protection of juveniles in Morocco (on cephalopods, through a closed-season area) and Norway (on cod, through ad hoc area closures) have also produced improvements in catch rates which tend to show that short-term benefits can also be expected in more temperate areas. Effective management can undoubtedly also lead to long-term increases in yield. This has been demonstrated for the northeast Arctic cod stock in the Norwegian and Barents seas which, in contrast to most other Atlantic cod stocks, has shown a recovery in spawning stock biomass from a depleted condition to a level not seen since the 1950s following a major reduction in fishing mortality in the late 1980s.²⁰

¹⁹ Garcia, S.M. 1986. Seasonal trawl bans can be very successful in heavily fished areas: the Cyprus effect. Fishbyte, April 1986: 7-12.

²⁰ ICES, op. cit., footnote 3, p. 32.

Summary of analyses, conclusions and diagnostics

Type of analysis		Conclusions	Diagnostics
TRENDS IN DEMERSAL FISH
Overall decrease		Production stable since the 1970s	Hiding overfishing
Sum of peaks minus present landings		In 31% of the FAO areas: increases In 67% of the FAO areas: decreases Minus 5 million tonnes	Largely owing to overfishing Possible increase unknown Obtainable through management?
TRENDS IN OVEREXPLOITED MARINE RESOURCES
Overall decrease		Minus 6 million tonnes since 1985	Overfishing
Sum of peaks minus present landings		Minus 9 million tonnes overall	Overfishing
TRENDS IN HIGHLY MIGRATORY AND STRADDLING RESOURCES
Highly migratory		Still increasing	Some overfished
Straddling		Minus 2 million tonnes since 1989	Mainly overfishing of Alaska pollock
TRENDS IN 200 MAJOR FISH RESOURCES
(accounting for 77% of world marine fish landings)		35% resources overfished 25% resources fully fished 40% still developing	60% need urgent management
TRENDS BY OCEAN			POSSIBLE ADDITIONAL PRODUCTION
Atlantic		Fully fished in 1980 (21.1 million tonnes)	No further increase
Pacific		Fully fished in 1999 (54.1 million tonnes)	Insignificant increase (+ 1.1 million tonnes) through development
Indian		Developing (5.4%/year, about 23.1 million tonnes)	Substantial increase (+ 16.1 million tonnes) through development to be verified
Mediterranean and Black seas		Developing (2.6%/year, 2.1 million tonnes)	Increase through eutrophication (likelihood unknown)
Three estimates of global marine potential:
	World ocean	Fully fished in 1996 (82.1 million tonnes)	Further increase unlikely
	Sum of oceans	Developing (100.1 million tonnes)	Substantial increase (+ 17.1 million tonnes) depends on reliability of Indian Ocean estimate. Mainly development
	Sum of areas	Developing (125.1 million tonnes)	Very substantial increase (+ 42.1 million tonnes) mainly from management and development. Highly unreliable

An important problem and opportunity are in the potential improvement from the reduction of unwanted by-catch. It has been estimated that 27 million tonnes of fish are discarded every year,²¹ comprising species of low commercial value but also a large proportion of juveniles. These 27 million tonnes are part of the catches, if not part of the landings, and are not included in the data used in this study, but nevertheless need to be taken into account for management. If added to the present landings, they result in a world marine catch of more than 110 million tonnes. The benefits resulting from a reduction of unwanted by-catch through the increased survival of juvenile fish can be very significant.

²¹ FAO. 1994. A global assessment of fisheries by-catch and discards. FAO Fisheries Technical Paper No. 339. Rome. 233 pp.

Increases in production would come from further fisheries expansion on those resources that are apparently still increasing their contribution to world landings (about 40 percent of major fish resources are classified as still developing in this study and FAO in 1994²² estimated 32 percent). It must be recognized that, although for these resources landings are still growing at a steady rate, it is not possible to have a reliable estimate of the potential. It would be a mistake, however, not to recognize that some potential exists.

²² FAO, op. cit., footnote 13, p. 42.

An important question is whether, at the global level at which the analysis has been conducted, improvements in yield from both demersal predators and pelagic prey can be expected. The pelagic group contains a number of significant predators, among which are the large pelagic tunas and tuna-like species. The demersal group contains a number of small species which are prey, and demersal fish eggs and larvae, during their early pelagic phases, are prey for the small pelagic species. The implications of these interactions are not easy to foresee and it is therefore impossible to establish how much of the present balance in the abundance (and potential) of pelagics and demersals results from the relative overfishing of the demersals and the resultant reduced pressure on pelagics. Neither is it possible to determine to what extent the rehabilitation of the overfished demersals will affect the survival and potential of the pelagics. The issue of resource rehabilitation at the large, regional scale has never been tackled and remains, with the issue of the medium-term variations of the small pelagics, one of the key issues of the management of fisheries for the twenty-first century.

In conclusion, while it must be recognized that the statistical significance of the most detailed analysis in this study is insufficient, the elements of information available indicate that an increase in fisheries production of at least 10 million tonnes is possible plus further increases in landings of an unknown magnitude obtained from fisheries development, as well as from mariculture. FAO in 1995²³ indicated that 20 million tonnes more landings might be obtainable. The results of the present study provide a firmer basis for believing that such an increase can be realized if: degraded resources are rehabilitated; underdeveloped resources are exploited further, avoiding, however, their overfishing and the overfishing of those resources that have already reached the highest level of sustainable exploitation they can stand; and discarding and wastage are reduced.

²³ FAO. 1995. The State of World Fisheries and Aquaculture. Rome. 57 pp.