Developing a strategy to ensure the sustainable use of living marine resources and their environment was only one aspect of man's relationship with the biosphere addressed at the UN Conference on Environment and Development (Rio de Janeiro, June 1992). However, this aspect poses particular problems for international collaborative management that do not apply to most terrestrial environments, where the ownership of resources and their environment, and the corresponding responsibility for their management, have usually been long established. The urgent need now is how to establish the conditions for sustainable development of living marine resources within the existing framework of rights and responsibilities for different maritime areas and resources. The beginnings of a consensus on this issue effectively date from the United Nations Convention on the Law of the Sea in 1982 (United Nations, 1983)1 which is used by most of the signatory States as a basis for relevant national and international legislation and State practice. The Convention came formally into force in November 1994.
However, many of the coastal States signatory to this Convention have not yet adequately evaluated the potential of the resources at their disposal, nor developed strategies for allocating to their own citizens the rights to, and responsibilities for, the marine resources within the maritime zones under their respective jurisdictions or sovereignty (notably, Exclusive Economic Zones). Nor have they all decided on conditions of access to foreign fishing vessels. Still fewer have developed frameworks for necessary collaboration with neighbouring countries sharing the same unit resources and protecting their common marine environment.
On a technical level, the fact that the living resources of seven-tenths of the world's surface (i.e., the oceans and seas) are made up of communities of wild animals, differentiates the use of these resources and their environments from the artificial mono- or polyculture systems of domesticated plants and animals typical of much of the productive land surface and of marine aquaculture. Consequently, the sustainable development of the living resources of the world's oceans has more in common with wildlife management than with most uses of terrestrial systems. The contrast between systems of culture of domestic animals and plants and the harvest of wild resources is simply stated: in the former case, the resource is usually harvested at an optimal age; in the latter case, the harvest is of a mixture of age groups, often containing mature and immature individuals, and often accompanied by other components of the ecosystem, whether of commercial value or otherwise, which if not retained by the harvester, usually experience discard mortality when returned to the sea.
Experience has shown that removing an excessively high proportion of such a continuously harvested renewable resource will compromise its sustainability and therefore the supply of food to future generations of human beings. For this reason, the concepts of conservation, development and access need to be reconciled before serious progress can be achieved in marine resource management.
1 Referred to as “the 1982 Convention” in this document.
Any discussion of the sustainable development (see definitions below) of the marine environment and its resources leads inevitably to a need for familiarity with a wide range of technical subjects, particularly with respect to living marine resources, their biology and environment. To avoid excessive technical vocabulary and explanations within the main body of the document, the reader is referred to Annex I which provides a brief glossary of some of the main terms and concepts used in this paper. However, certain basic terms and concepts need to be defined and discussed at once.
In view of the intimate connection between resources and their environment, and for the sake of convenience, the term resources will, hereafter, be generally used to refer to the living marine species potentially or presently subject to exploitation by man for food, feed, fertilizer or the production of other products of value or use, it being understood that a living marine resource cannot be dissociated from its environment. Moreover, the term fish will be generally used to cover fish proper, as well as shellfish and all other groups of marine organisms exploited for human use or consumption.
The International Union for the Conservation of Nature (IUCN) and definition of conservation given in the “World Conservation Strategy” (IUCN, UNEP and WWF, 1980), is “the management of human use of the biosphere so that it may yield the greatest sustainable benefit to present generations while maintaining its potential to meet the needs and aspirations of future generations”.
The same document defines development as “the modification of the biosphere and the application of human, financial, living and non-living resources to satisfy human needs and improve the quality of human life”. The apparent incompatibility of these two processes led to the concept of sustainable development which is discussed below.
The concept of sustainable development was at the core of the debate at the 1992 UN Conference on Environment and Development in Rio de Janeiro. The need for sustaining improvements in human well-being, while pursuing policies compatible with the capacity of the global environment to sustain them over the long term, has led in recent years to the ideal of sustainable development. This concept embodies the idea of “progress”, the motive force for technologically driven changes since the middle of the last century, and the idea of “stability”, the ability of mankind to extract a constant level of benefits from an ecosystem over an indefinite period. The more limited notion of development therefore embodies the notion of exploitation or harvesting of natural resources; however, such exploitation must be constrained by the capacity of the exploited resource and its natural environment to resist the impact of exploitation, if such development is to be sustainable. The pursuit of “progress” without restrictions has had negative effects on marine, as well as terrestrial, environments; this document briefly describes these effects for the marine environment without going into detail.
Various definitions have been proposed for this new, environmentally more appropriate, approach to development. The definition of sustainable development adopted by the World Commission on Environment and Development in 1987 (Anon, 1987) is perhaps the simplest:
“Development that meets the needs of the present without compromising the ability of future generations to meet their own needs.”
This definition recognizes that the value systems of society are continuously changing, as will the relative value currently assigned to a particular living resource.
A more explicit definition for aquatic and terrestrial systems, adopted by the 94th FAO Committee on Fisheries in 1991 (COFI 1991), is:
“Sustainable development is the management and conservation of the natural resource base, and the orientation of technological and institutional change in such a manner as to ensure the attainment and continued satisfaction of human needs for present and future generations. Such development conserves land, water, plant and genetic resources, is environmentally non-degrading, technologically appropriate, economically viable and socially acceptable.”
Clearly, this definition places the satisfaction of human needs in a central position, and recognizes, as does the concept of intergenerational equity mentioned at UNCED, that fishers have a right to a livelihood, but a responsibility to see that their offspring, and the following generations, have similar prospects. Clearly to satisfy this statement of equity it will be necessary that such fishers leave the resource: ‘in, or close to, the same state that they found it in’. To achieve this result, a Code of Conduct for Responsible fishing is being developed by FAO at the request of its member countries, first expressed at the 1993 Cancún Conference (FAO, 1992c).
The FAO Committee on Fisheries definition of sustainable development was primarily aimed at the harvesting of resources, but could also apply to recreational or other uses that do not lead primarily to resource depletion. It is clearly intended to encompass three main types of activity:
those activities that fall within the classical concept of development, namely, the economic growth resulting from newly exploited resources, without compromising the capacity of the resource base and its environment to sustain the exploitation;
any modification of the level of use of resources that are already being exploited, while diversifying this use so as to render exploitation more productive and cost effective, and to reduce the impacts of resource use on other components of the ecosystem and on other human endeavours;
the rehabilitation of ecosystems degraded by past destructive exploitation, so as to restore them to productive use.
It is clear that sustainability refers to the resources and also to the fishery that exploits them (Christie, 1993). In the marine context, however, it should be borne in mind that sustaining a resource and sustaining a fishery on that resource, are, in many respects, independent objectives.
To what extent, and under what conditions, are the above-mentioned criteria feasible objectives for man's use of marine life, and to what extent, and following what strategies, is sustainable development a feasible objective for management of marine resources? This document attempts to address such questions and to raise some related issues for future discussion. It is, however, clear that the achievement of sustainable development will involve a long struggle, with many hard lessons learned by each country as it attempts to apply general principles to its specific circumstances.
Beside fishing, other human activities, as well as natural changes, affect the marine environment and, consequently, the living marine resources they contain. Certain living marine resources and marine ecosystems resist well the impact of certain of these activities on the marine environment, in which case they are often described as “robust”. Other marine ecosystems and resources have little resistance, and are often called “fragile”. Since the system and the source or cause of the impact need to be specified, these terms are often rendered meaningless or vague, since the so-called “fragile” ecosystems have been almost as successful in surviving so far, as the “robust” ones. The term “susceptible” is preferred, since the particular factors impacting the resource need to be specified.
The susceptibility of a marine resource or an ecosystem to changes induced by outside forces, such as pollutant inputs or climatic changes, has been defined by Sherman and Solow (1992). Starting from the concept of ecosystem “health”, they consider the term to describe the resilience, stability and productivity of the ecosystem in relation to its changing state. Constanza(1992), considered that, for an ecosystem to be healthy and sustainable, it must maintain its metabolic activity, its internal structure and organization, and be resistant to external stress over relevant time and space scales. These conditions of health and sustainability can be measured in terms of five variables: diversity, stability, resilience, production and yield. Rapport et al. (1985) and Berkes et al. (1993), among others, have considered in some detail ecosystem behaviour under stress.
Harvesting components from an ecosystem, taps the continuous flow of energy and materials produced by the primary source of most organic material, using the sun's energy by photosynthesis, as it flows upwards through the food web towards the apical predators. Such a food web can be considered a “dissipation structure” in thermodynamic terms (Caddy and Sharp, 1984): harvesting one node of the food web too intensively, will cause energy to be diverted into other food web components which may not be so suitable for human needs.
Diversity indices are measures of richness (the number of species in a system); and to some extent, evenness (variances of species' local abundance) (Pielou, 1975). They are therefore indifferent to species substitutions which may, however, reflect ecosystem stresses (such as those due to high fishing intensity) (Pielou,op.cit.; Rapportet al., 1985).
Stability implies the ability of all characteristic variables of a population/ecosystem to return towards initial equilibrium values following a disturbance that displaces that equilibrium. (The system is locally stable if the return is in response to local perturbations, and globally stable if it is stable when all the local perturbations cancel out when added up over the whole area of the species). It is worth noting here that past perceptions of a state of equilibrium or ‘state of rest’ to which populations return after being perturbed, is less well accepted by oceanographers and marine scientists. Long term fluctuations are more typical, often over decadal scales (Lluch-Belda et al., 1992), to which the effects of climate change on marine systems can now be added (Ramanathan, 1988; Bakun, 1990).
Resilience is the rate of return of a stable population/ecosystem to its undisturbed equilibrium (Pimm, 1984), or more broadly, the ability of a system to maintain its structure and patterns of behaviour in the face of a disturbance (Holling, 1986).
Production in the strict sense, is the biomass generated by the population or ecosystem per-unit-time, whether or not this is harvested or consumed within the food web by other species (Allen, 1971). We often refer to “fisheries production” however, which is usually meant to include harvested biomass.
Yield is the amount of biomass that can be harvested without compromising the ability of the population/ecosystem to regenerate itself. The term sustainable yield is sometimes used in this same sense, as that yield which can be harvested without compromising the continuity of fishery production (Gulland, 1977); while noting that modern experience shows that this is not a constant value, and constantly varies in light of climatic regime changes.
Besides the glossary in Annex I which attempts to define some other useful terms, a list of acronyms is given in Annex II, and a list of selected references to further useful reading on the issues discussed here is given in section 8.
The kinds of responses likely to occur in a population of a species, hence in its ecosystem as a whole, are, for example, redistribution (to avoid an adverse environmental condition), changes in growth rate, mortality rate, fecundity, recruitment and in terms of sustainable development, it is obvious that a better understanding of the ecological susceptibility of a resource to forces leading to environmental change is a keystone of effective fishery management (Caddy and Sharp, 1986). The attainment of a steady state of development of any kind has been called into question (e.g. Simon 1989), and for marine fisheries it is clear that few fisheries landing trends show any form of stability (Caddy and Gulland, 1983; Hilborn and Walters, 1992), and the current paradigm is of resources showing wide fluctuations with environmental changes and economic cycles, resulting in fleet investment schemes which themselves usually depart widely from a steady state (Caddy, 1993b).
The distribution of biological production through the world's oceans, as for the distribution of living resources, is far from uniform (Fig. 1): the great majority of fishery production occurs within 200 miles of land; hence marine fishery resources are highly susceptible to the impacts of human activities.
The effects of the development of human activities on marine ecosystems has also not been uniform; some systems have shown considerable adaptability to high levels of human impact, whereas others have already been seriously affected. For this reason, this document treats the following ecological provinces separately within the global marine environment, with respect to the state of the resources and their environment, their development potentials, and the key actions considered necessary to promote sustainable development.
Although certain problems arise in more than one ecological province, it is practical to distinguish the following provinces:
nearshore waters and estuaries - basically including the land-sea interface and the marine element of the coastal zone;
coastal and shelf seas - the margins of oceans and open seas between the coastal zone and the edge of the continental shelf out to 200 miles and/or the 200-m isobath (which roughly corresponds in many areas to the limits of the Exclusive Economic Zone under the 1982 UN Convention on the Law of the Sea);
enclosed and semi-enclosed seas - combining many of the considerations applicable to (1) and (2), above, but with the problems specific to such seas;
the high seas and open ocean - the seas beyond the continental shelf and/or EEZ, not subject to any national jurisdiction;
the Antarctic - the seas bordering the Antarctic continent, sometimes collectively referred to as the Southern Ocean; also not subject to any national jurisdiction, but presenting specific ecological characteristics not easily assimilable to any of the foregoing ecological provinces.
Figure 1. The first global view of the geographical distribution of the production of plants (phytoplankton) in the oceans forms the basisd for food chains leading to marine fisheries, is redrawn from a composite image of ocean chlorophll production based on remote sensing imagery for 1978-81 prepared under the NSF/NASA- sponsored, US Clobal Ocean Flux Study (from FAO. 1994b).
A separate section (2.6) is devoted to the special problems of apical prodators, those species at the peak of the marine food chain, in the marine ecosystem and to endangered species, many of which are also apical predators.
The speicial problems of each province are dealt with in the respective sections, whereas the main problems common to all or most of these provinces are dealt with later in the document.
Although the initial approach is based on five major ecological provinces (sections 2.1. to 2.5), it may also be useful to consider alternative geographical/ecological subdivisions of the marine environment and its resources which may be applied to a consideration of the sustainable development of the resources (Fig. 2).
Figure 2. Three alternative frames of reference for studies on marine
ecosystems illustrated for a semi-enclosed sea:
A: The large Marine Ecosystem Concept (LMG)
B: Integrated Water Area Management (ICAM)
C: The Marine Catchment Basin Approach (after Caddy, 1933a)
The concept of Integrated Coastal Area Management (ICAM) (see e.g. FAO, 1991c; Clark 1992; Chua and Fallon Scura, 1992; Pernetta and Elder, 1993) is obviously the context for discussion of the multiple interactions at the land-sea interface; in practice, this essentially means within roughly 5 km of this interface, although some activities, such as fishing and marine mining, taking place further offshore, or others, such as coastal construction, industrial installactions and others activities affecting the exchanges at the land-sea interface, but occurring further inland, may also be of great importance to the marine environment but do not fall in the classical ICAM context. The main objective of Integrated Coastal Area Management is to harmonize those human activities which require for their success proximity to the land-sea interface in such a way as to minimize their impact on the coastal zone environment and natural resources. Such management requires some hard choices, and this subject is treated in somewhat more detail in section 5.11.
The Marine Catchment Basin (MCB) concept (Caddy, 1993a; Caddy and Bakun,1995) aims at the integration of events within the catchment basins of rivers draining into the sea, with the ecology of the receiving sea itself. This approach (effectively that adopted for the Mediterranean Blue Plan and underlying the Helsinki Convention for the protection of the Baltic environment, Anon (1986); Ambio (1990)), is obviously relevant to estuaries, coastal lagoons and semi-enclosed and coastal seas where activities in marine and freshwater aquatic systems need to be integrated, and where transfers of materials to an enclosed or semi-enclosed marine system have an overriding influence.
The concept of the Large-Scale Marine Ecosystem (LME) (Sherman and Alexander, 1986; Sherman et al., 1990; Sherman and Solow, 1992) is most readily applicable to discrete shelf and ocean systems, where terrestrial inputs can be treated as extrinsic to the marine system as a whole. Sherman and Alexander (1986) defined LMEs as “externsive areas of ocean space of approximately 200 000 km2 or greater chareacterized by distinct bathymetry, hydrography, productivity, and trophically dependent populations.” LMEs may include areas of upwelling of nutrient-rich bottom water, or be major areas of retention of stratified shelf water, boundary current systems and other comparable oceanic systems.
All of the foregoing frameworks require the development of relevant marine scientific research, and monitoring of the marine environment, the resources, the fishing effort, catches and landings. Particular attention is therfore given to these topics.
Few fisheries can be sustainably developed in isolation, even at the local and national levels, because of the interconnectedness of the marine environment. Markets for fish and fish products have also become more and more regional or global. There is therefore a need for an international institutional and legal framework. This framework is defined, in parctice, by major regional or global conferences and the conventions or formal declarations arising from them. The role of regional fishery commissions, and international organizations directly concerned with marine resources are particularly stressed in the UN Convention on the Law of the Sea. The pursuit of optimum harvesting and of the necessary research this entails are also stressed in Agenda 21 (see section 7.3 and Annex VII) which was the main result of the Conference on Environment and Development, in the pursuit of sustainable development of such resources. The effectiveness of the various fishery commissions and fishery conventions is also considered in section 7.5.
A major section (4) is devoted to the optimum harvesting of the resources; that is, their sustainable development which has long been the principal objective of fishery management. As noted, the pursuit of such development is considered to be through responsible fishing which means, essentially, the pursuit of rational fishery management objectives in a broad sense - from consideration of the resource and its environment, to the processing and marketing of the fish;taking into account socio-economic, legal and administrative factors.
Opposing the achievement of rational fishery management objectives are the damaging effects of uncontrolled fishing. Which is now being counteracted by FAO through the development of a Code for Responsible Fishing (see section 4.4).
First, the damaging effects of unrestrained fishing and fleet growth leading to over-capitalization of the fishing industry has resulted in less than optimum harvesting in many fisheries. A relatively small number of famous examples such as the cessation of fishing in the North Sea and recovery of North Sea plaice stocks after a period of `biological repose' during the 2nd world War (noted by Beverton and Holt, 1957) are however often cited to show that stock recovery is possible once fishing pressure is relieved. Similar revoveries have also been shown by some seal populations once hunting has been brought under control. Other impacts of fishing such as the effects of trawling on the marine fauna and flora of the sea floor (e.g. Van Dolah et al., 1991) are much more difficult to document, and are only now receiving much research attention.
Second, considerable difficulties remain in predicting the effects on the resources of short- (seasonal) and long-term (interannual to decadal) variations in the marine environment. There may also be a need to assess the relationship between these variations and the long-term global changes thought to be occurring, mainly as a result of the so-called “greenhouse” effect (see section 5.10).
Third, the damaging effects on the resources of other activities besides fisheries constitute a constraint on optimum harvesting, generally by preventing a fish stock from maximizing its production or by restricting the livable space the stock could occupy. Such activities are usually those of Man, such as: coastal construction and mining; disposal of coastal urban and industrial wastes and coastal aquaculture, and natural run-off from the land, directly or via rivers, and via atmospheric deposition, of nutrients, industrial effluents and pesticides (GESAMP, 1982;83;86;90;91) (Fig.3).
Progressively more frequently, the accidental or intentional introduction of exotic species, including red tide species (White et al., 1984) and larger organisms (Hallegraff and Maclean, 1989; Granelli et al., 1990; Carlton, 1989 and Carlton and Geller, 1993), are having significant effects on marine systems. One notable example described recently, resulted from the introduction of a ctenophore, Mnemisopsis leydei,through ship ballast water into the Black Sea, where it has had a disastrous impact on pelagic fish stocks (GFCM, 1993).
Finally, the adoption of Integrated Coastal Zone Management (e.g. Chou et al., 1991) may help provide a framework to limit fishing in coastal waters (wetlands, lagoons, estuaries, inshore/coastal seas to sustainable levels). In this case, the constraints on harvesting may be conducive to optimum harvesting, hence sustainable development. New options for sustainable harvesting of the resources should be considered in the context of responsible fishing and rational management, on a sound scientific basis (e.g. Chou et al., 1991).
The interconnectedness of the marine environment and the indifference of marine organisms to man-made political boundaries (such as Exclusive Economic Zones: EEZs) demands an international and/or intergovernmental context for many aspects of fishery research, monitoring and management, and for sustainable development of marine resources in general. Annex III provides some information on the international organizations, regional fishery commissions and conventions concerned with marine resources and their environment, giving the main lines along which they work, the difficulties they face and their requirements if they are to succeed in achieving sustainable development of marine resources.
Figure 3. Some synergistic effects on fisheries and marine ecosystems of 3 Key results of human activities (from Caddy and Bakun, 1995).
A large number of priorities for action were proposed by FAO at UNCED for the consideration of these international organizations, regional fishery commissions and, above all, the Member States of these various organizations and commissions which are the signatories to the relevant conventions. These are briefly summarized following each section.
