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Article 36 of the FSA that entered into force on 11 December 2001 states that four years after the date of entry into force, the Secretary General of the United Nations shall convene a conference with a view to assessing the effectiveness of the Agreement in securing the conservation and management of straddling fish stocks and highly migratory fish stocks and that this conference shall review and assess the adequacy of the provisions of the Agreement and, if necessary, propose means of strengthening the substance and methods of implementation of those provisions in order to better address any continuing problems in the conservation and management of straddling fish stocks and highly migratory fish stocks.

In preparation for the aforementioned review, the Fourth Informal Meeting of the States Parties to the FSA, held at the United Nations, New York, 31 May - 3 June 2005, agreed that the review should consider "discrete high seas stocks and non-target and associated dependent species" in addition to highly migratory species and straddling stocks.

2.1 Species and stock terminology

The biological definition of species (as a group of living organisms consisting of individuals capable of exchanging genes or interbreeding) is straightforward and does not pose major problems of nomenclature for fish and for other living organisms exploited by fishing ("species" are the fundamental taxonomic units of biological classification). However, the definition of "stock" varies greatly according to the knowledge and information available as well as the purpose and type(s) of fishery under consideration. Sparre and Venema (1998) provide a detailed description of "the stock concept" and from the fisheries management point of view the most suitable definition of "stock unit" is probably the one provided by Gulland (1969; 1983) who, on operational criteria and practical grounds, proposed that a group of fish can be treated as a "stock" and managed as an independent unit if the results of assessment and the impact of management measures do not differ significantly from what they would be in the case of a truly independent stock.

Generally speaking, a "stock" is a subset of a species with similar growth and mortality parameters within a given geographical area and with negligible interbreeding with other stocks of the same species in adjacent areas. In practice, the application of the concept varies considerably depending on the knowledge available and acceptable complexity in management: for salmon, a river may contain several stocks, one for each of the tributaries where spawning occurs, while for swordfish there are two stocks in the Atlantic (north and south) and one in the Mediterranean. In some cases, a stock can include more than one species (e.g. some redfish [Sebastes spp.] stocks in the Northwest Atlantic).

With advances in population genetics, it is clear that the stock structure of many species is much more complex than is captured by stock definitions for management purposes. In some cases, stocks are being redefined based on this new information. However, for the purpose of this review, the concept of "stock" adopted has been that used in the original publications from which stock assessments have been compiled. When the assessment is based on FAO statistics, the term "stock" has been applied to species-area combinations with the resolution of statistical areas used for reporting capture production to the FAO Statistical Database. In some cases, it has been necessary to combine more than one species in a "stock".

For the purpose of this review, highly migratory stocks are those composed of highly migratory species as listed in Annex 1 of UNCLOS. This is a legal definition rather than a scientific definition based on the actual migratory behaviour of the species. Nevertheless, the species listed in Annex 1 are in general capable of migrating relatively long distances, and stocks of these species are likely to occur both within EEZs and on the high seas. Where available, information on individual stocks will be provided. It is noted that whales (i.e. Cetaceans) are included in Annex 1 of UNCLOS as highly migratory species. The International Whaling Commission (IWC) has management authority for the harvest of whales. At present there is a moratorium on commercial whaling, although there is some aboriginal subsistence whaling, whaling under scientific permits, and whaling in coastal State waters by countries lodging an "objection" within the IWC. Whaling is not addressed in the FSA and Cetaceans are not considered in this review.

UNCLOS does not use the term "straddling stocks", but article 63, clause 2 refers to: "the same stock or stocks of associated species[which] occur both within the exclusive economic zone and in an area beyond and adjacent to the zone", and this will be taken as a working definition of the concept of straddling stock in this document. The FSA, while using the term extensively, does not specifically define it although the above definition ("stocks occurring both within and beyond the exclusive economic zone") is used in explaining the meaning of straddling stocks when using some of the other official languages of the Organization.

The concept of straddling fish stock can cover a continuum from most of the fish being inside the areas of the EEZs under national jurisdiction to most of the fish being in an area beyond and adjacent to it, that is outside EEZs (in the high seas). No minimum portion outside or inside has been defined, but usage seems to indicate that as long as there is some directed fishing effort at catching the stock on either side of the EEZ line, it is considered to be straddling. For example, the so-called northern cod (NAFO Divisions 2J3KL) was considered a straddling stock even though 95 percent of the biomass was typically within the coastal State's EEZ.

Neither the term discrete high seas fish stocks nor the concept behind it are used in UNCLOS although Part VII of the Convention addresses the living resources of the high seas in general. Neither does the term or concept appear in the FSA, because of the nature and scope of the Agreement as originally conceived and negotiated. FAO (1994) used the term "purely high seas stocks" for stocks that are not found within EEZs. However, specifying that fish stocks not found within EEZs are "purely" or "entirely" high seas stock seems redundant and could even be misleading since all the other fish stocks that may occur in the high seas are already described in the relevant sections of UNCLOS dealing with the living resources of the EEZs, as well as in the FSA, either as "straddling stocks" if occurring both within the EEZs and in the high seas or as "highly migratory stocks" if composed of species listed in Annex 1 of UNCLOS, independently on whether they occur within the EEZs and/or in the high seas (it is noted that most if not all highly migratory stocks will represent a subtype of "straddling stock" subject to slightly different arrangements from those applicable to the other living marine resources of the EEZ as addressed in Part V of UNCLOS). Therefore, in this review the term high seas stocks will be used to refer to stocks that are purely or entirely in the high seas, that is for stocks that are neither highly migratory nor straddling. It is preferred to "discrete high seas stocks" because the discreteness of such stocks is generally unknown (e.g. fish caught on distinct seamounts hundreds or thousands of kilometres apart may not necessarily belong to discrete/separate biological units). Some distinction will need to be made however when referring to "high seas (fishery) resources" as these will include those portions of the highly migratory and the straddling stocks occurring in the high seas in addition to all the high seas stocks, occurring entirely in the high seas.

The exploitation of high seas stocks is relatively recent and less is known about their biology and stock structure than is the case for tunas or tuna-like species, or the more traditional fishery resources on the continental shelves which have been exploited and studied for much longer. Individual aggregations of those high seas stocks may belong to isolated stocks, individual stocks with some mixing with other stocks, or a larger stock occupying an area much larger than that covered by individual aggregations. Individual aggregations may also form a metapopulation (Levins, 1969). The concept of metapopulation implies that some of the aggregations (sinks) may be dependent on other aggregations (sources) for their recruitment and may not be self-sustaining. Fishery management should take account of the stock structure and it would be particularly important to acquire the necessary knowledge before exploitation proceeds too far. The list of (entirely) high seas stocks (section 5) used in this review is considered provisional as new resources continue to come under exploitation. It is understood that if individual high seas concentration of a given species identified as high seas stocks are found to belong to a much larger population as described above and part of this larger population also occurs within the EEZs, the species-stock in question will need to be reclassified as straddling, rather than as high seas stocks, particularly if there is a strong dependance for recruitment and sustainance.

Figure 1 illustrates the several configurations of highly migratory fish stocks, straddling fish stocks and (entirely) high seas stocks. The straddling stocks show the most varied possibilities: they can be found mostly inside one EEZ, mostly on the high seas, evenly distributed between EEZs and the high seas, straddling stocks can also be transboundary.

Associated and dependent species are caught and/or impacted in fisheries for straddling fish stocks, highly migratory fish stocks, and high seas fish stocks. Since any landed catch that is not from a straddling fish stock or highly migratory fish stock may be regarded as from high seas fish stocks, this review considers associated species as impacted species that are not part of the landed catch.

This document does not consider EEZ stocks found either entirely within one country's EEZ or stocks occurring within the exclusive economic zones of two or more coastal States but not on the high seas, or the sedentary species of the continental shelf in the sense described in Article 77 of UNCLOS, regarding " organisms belonging to sedentary species, that is to say, organisms which, at the harvestable stage, either are immobile on or under the seabed or are unable to move except in constant physical contact with the seabed or the subsoil" with respect to continental shelf resources, and are subject to the jurisdiction of coastal nations.

2.2 Approach including data issues

This review builds on a review of highly migratory fish stocks and straddling fish stocks prepared by FAO (1994) as input to the negotiations for the FSA, and on FAO's (2005a) most recent published review of the state of world marine fisheries. In some cases information from FAO (2005a) was updated based on information provided by Regional Fishery Organizations (further information on Regional Fisheries Organizations can be found in the following FAO Web site: and in particular, information received from the Commission for the Conservation of Southern Bluefin Tuna (CCSBT), the Indian Ocean Tuna Commission (IOTC), the Inter-American Tropical Tuna Commission (IATTC), the International Commission for the Conservation of Atlantic Tunas (ICCAT), the Northeast Atlantic Fisheries Commission (NEAFC), the Secretariat of the Pacific Community (SPC), and the International Council for the Exploration of the Sea (ICES). Unless otherwise stated, the catch information is from the FAO Fisheries Statistics Database. The most recent complete year of data is 2004 (FAO, 2006a; FAO Fishery Information, Data and Statistics Unit, in press).

FIGURE 1. Types of stocks occurring partially or entirely in the high seas. Top panel: 1. Highly migratory; 2. Straddling (extensive distribution); 3. High seas. Bottom panel: 4. Pelagic straddling (mostly within EEZ); 5. Demersal straddling (mostly within EEZ); 6. Straddling (transboundary); 7. Straddling (mostly in high seas); 8. Straddling (evenly distributed)

At present, there is no global inventory of fish stocks, although one is called for in the "Strategy for Improving the Information on the Status and Trends of Capture Fisheries" approved by the FAO Committee on Fisheries (COFI) on 28 February 2003 (FAO, 2003d). FAO is developing a Fisheries Global Information System (FIGIS) (FAO, 2006b), which will fulfil this need, but unfortunately, it is only sparsely populated with stock information at this stage of development. The available FAO global fisheries statistics database is by country, species and major FAO fishing areas for statistical purposes (Figure 2). These statistical areas are generally too coarse to correspond to stocks, except for tunas where catches by stocks are included in the FIGIS database, and the data available at present does not distinguish EEZ catches from catches on the high seas. Therefore, it is necessary to make informed judgements for each FAO statistical area about which species are fished partially or entirely on the high seas.

FAO marine major fishing areas for statistical purposes

For the purpose of describing their state of exploitation, species/stocks were classified according to a classification scheme used previously by FAO as follows:

Not known (N): not much information is available to make a judgement;

Underexploited (U): undeveloped or new fishery. Believed to have a significant potential for expansion in total production;

Moderately exploited (M): exploited with a low fishing effort. Believed to have some limited potential for expansion in total production;

Fully exploited (F): the fishery is operating at or close to optimal yield/effort, with no expected room for further expansion;

Overexploited (O): the fishery is being exploited above the optimal yield/effort which is believed to be sustainable in the long term, with no potential room for further expansion and a higher risk of stock depletion/collapse;

Depleted (D): catches are well below historical optimal yields, irrespective of the amount of fishing effort exerted;

Recovering (R): catches are again increasing after having been depleted or a collapse from a previous high.

Although more detailed information is provided within each regional review chapter, in summarizing the state of regional and global fishery resources FAO (2005a) reports on 584 species (or species group) statistical area combinations, for which the state of 441 (76 percent) is reported known. While these species (or species group) statistical area combinations are referred to as stocks, in many cases they are a collection of several stocks according to either a management or biological perspective. For example, in summarizing the state of cod in the northwest Atlantic (FAO statistical area 21) the species statistical area combination is treated as a single entry, although there are ten separate management units for cod fisheries in the area, and often more than one reproductively isolated breeding population (i.e. stocks from a biological perspective) probably exists in some of these management units. In spite of these limitations, the state of stocks as reported in FAO (2005a) was used herein as the best available global source of stock state information, with refinements based on more recent information provided by some Regional Fisheries Bodies or fishery specific knowledge of FAO Fisheries Department staff or its consultants.

Information on (associated and dependant) species associated with fisheries for highly migratory species, straddling fish stocks and high seas fish stocks is very limited. Rarely are catches of these species reported. Most are discarded at sea. Some countries collect data on discards, but the information is incomplete and it is not routinely reported to FAO. However, FAO recently published an update of information on fishery discards (Kelleher, 2005) which provides useful information on associated species. The status of some of the species is known from various sources (for example, some sea turtle populations are in danger of extinction while others are giving signs of recovery), but almost nothing is known about the status of others. Thus, this review highlights known and potential issues concerning associated species, but a comprehensive assessment is not possible.

Various FAO information resources were used as sources of information on the biological characteristics and geographical distribution of the species. These include the FAO species catalogues and other information products provided by the FAO Species Identification and Data Programme (SIDP,, FIGIS species fact sheets ( and Fishbase (

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