Global overview of marine fishery resources

Table of Contents

• Overview
• Profile of catches
• State of exploitation
• Discussion
• Source of information

Overview

Marine fisheries are very important to the economy and well-being of coastal communities, providing food security, job opportunities, income and livelihoods as well as traditional cultural identity. They produced 80 million tonnes of fish in 2009 and directly employed 34 million people in fishing operations in 2008 (FAO, 2010). Fish and fishery products are a vital and affordable source of high-quality protein, especially in the world’s poorest nations – in 2008, fish supplied more than 3 billion people with at least 15 percent of their average animal protein intake (FAO, 2010). Therefore, maintaining the long-term prosperity and sustainability of marine fisheries is not only of political and social significance but also of economic and ecological importance. The United Nations Convention on the Law of the Sea (UNCLOS), the United Nations Fish Stocks Agreement (UNFSA [UN, 1995]) and the FAO Code of Conduct for Responsible Fisheries (FAO, 1995a) all require maintaining or restoring fish stocks at levels that are capable of producing their maximum sustainable yield (MSY). To fulfil the objectives of these international treaties, fishery management authorities need to undertake assessment of the state of fish stocks and develop effective policies and management strategies. As the United Nations (UN) Agency with a mandate for fisheries, FAO has an obligation to provide the international community with the best information on the state of marine fishery resources.

FAO undertook an assessment of marine fishery resources in 1973, originally at the request of the Sea Bed Committee in preparation for the UN Conference on the Law of the Sea. The FAO Committee on Fisheries (COFI) in its Eighth Session report expressed the view that such an appraisal of the world’s fishery resources should be updated with the most recent statistics and presented at future COFI meetings (FAO, 1974). This effort to assess and report on the state of global marine fishery resources was then followed up through a series of brief summary updates (FAO, 1974, 1978, 1979, 1981, 1983, 1985, 1987, 1989, 1990, 1992). These reports were prepared as background information documents for the regular sessions of COFI. This reporting became a series of regular stand-alone publications (FAO, 1994, 1995b, 1997a) and later as contribution sections to the FAO flagship publication The State of World Fisheries and Aquaculture (FAO, 1997b, 1999, 2000, 2002, 2004). The State of World Fisheries and Aquaculture also has a primary objective of providing updated information to COFI. It also provides an update, more generally, to policy-makers, civil society and all those who derive their livelihood from fisheries and aquaculture, while covering a much broader range of issues affecting these sectors.


This paper presents a major assessment and update since the last comprehensive review in 2005 (FAO, 2005). It is an update on the state of world marine fishery resources provided in the most recent biennial updates for The State of World Fisheries and Aquaculture 2010 (FAO, 2010). While the general focus and outlay of previous major reviews have been maintained to the extent possible, several changes have been introduced in this volume in response to comments and suggestions received from copy and electronic Web-based publishing possibilities.
This review consists of four major components. The first part provides a global overview of marine fishery production and the state of marine fish resources (Chapter A1). The second part is divided into chapters (Chapters B1–B16) that summarize and compile the information available for each FAO major fishing area for statistical purposes (Figure A1). The third part focuses on special topics that attract great attention in the international community, including tuna and tuna-like species, sharks, the Pacific islands region, deep-sea fisheries, and fisheries and long-term climate variability (Chapters C1–C5). The final part lists all the tables that provide details about trends in catches and, where feasible, on the state of exploitation of stocks. The final set of tables in Part D summarize and complement the reviews by major fishing areas and main species groups organized according to the International Standard Statistical Classification of Aquatic Animals and Plants (ISSCAAP) grouping.

PROFILE OF CATCHES

The world’s fisheries and aquaculture sectors have gone through a dramatic development in the last 60 years, and there have been large increases in their production. Total world fish production was only 19.3 million tonnes in 1950, but it increased dramatically to 163 million tonnes in 2009 (Figure A2). Marine capture fisheries have always been the largest contributor to world fish production. In 1950, marine captures were 16.7 million tonnes and accounted for 86 percent of total world fish production. In the last two decades, marine and inland aquaculture has expanded rapidly, and the relative contribution of marine capture fisheries to the growing total world fish production has shrunk. Nevertheless, marine capture fisheries still contributed 49 percent of the world’s fish production in 2009, the largest sector in comparison with mariculture (21 percent), freshwater aquaculture (23 percent) and inland capture fishery (6 percent) (Figure A2).

Marine fisheries have experienced different development stages, increasing from 16.7 million tonnes in 1950 to a peak of 87.7 million tonnes in 1996, and then declining to stabilize at about 80 million tonnes, with interannual fluctuations. Global recorded production was 79.5 million tonnes in 2009 (Figure A2). Rapid development was seen in the late 1950s and 1960s and between 1983 and 1989. The first boom was believed to be caused mainly by the post-war shipbuilding expansion in the 1950s, the new technologies such as steam and motor trawlers in the 1960s, and the extension of jurisdiction to 12 nautical miles by most costal States – this is the region that encompassed the ocean’s most productive upwelling and continental shelves (Sanchirico and Willen, 2007; Engelhard, 2008). The second rapid expansion was associated with the extension of jurisdictions from 12 to 200 nautical miles with the establishment of exclusive economic zones (EEZs) under the legal foundation of the UNCLOS (Sanchirico and Willen, 2007).

After reaching a peak in 1996, global landings decreased gradually, dropping by about 10 percent by 2009. Subsequent fluctuations mainly reflect the variation in catches from a few highly productive areas, particularly in the Northwest Pacific (Area 61) and the Southeast Pacific (Area 87). These areas account for a large portion of landings from pelagic species.


Regional patterns in landings
Based on the average catches in 2005–09, the Northwest Pacific is the largest contributor (25 percent) to the global catch, followed by the Southeast Pacific (16 percent), Western Central Pacific (14 percent), Northeast Atlantic (11 percent) and Eastern Indian Ocean (7 percent). All other FAO areas contribute less than 5 percent of the global total catch.

World marine fisheries have gone through significant development and changes since 1950 when FAO started collecting fisheries statistics data. Accordingly, the levels of exploitation of fish resources and their landings have also varied over time. The temporal pattern of landings differs from area to area, depending on the level of urban development and changes that countries surrounding that area have experienced. In general, they can be grouped into three types. The first group are those FAO areas that have demonstrated oscillations in total catch (Figure A3). They are the Eastern Central Atlantic (Area 34), Northeast Pacific (Area 67), Eastern Central Pacific (Area 77), Southwest Atlantic (Area 41), Southeast Pacific (Area 87), and Northwest Pacific (Area 61). These areas provide about 53.5 percent of the world’s total catch. Some areas in this group may have shown a clear drop in total catch in the last few years, e.g. Northeast Pacific, but, over the longer period, a declining trend is not evident.


The second group consists of areas that have demonstrated a decreasing trend in catch since reaching a peak at some time in the past. This group contributes 19.9 percent of global catch on average in the last five years, and includes the Northeast Atlantic (Area 27), Northwest Atlantic (Area 21), Western Central Atlantic (Area 31), Mediterranean and Black Sea (Area 37), Southwest Pacific (Area 81), and Southeast Atlantic (Area 47). It is interesting and noteworthy that such declines occurred at different times: in the Northwest Atlantic in the late 1960s; in the Northeast and Southeast Atlantic in the mid-1970s; in the Western Central Atlantic and Mediterranean and Black Sea in the mid-1980s; and in the Southwest Pacific in the early 1990s (Figure A4). This sequence largely reflects the fact that areas surrounded by the most-developed countries experienced the earliest decline in catches.

The largest decline was seen in the Northwest Atlantic, where landings dropped by 55 percent from their peak to 2009. The second-largest drop was in the Western Central Atlantic with 46 percent, followed by the Southwest Pacific with 37 percent and the Northeast Atlantic with 35 percent. The total catches in the Mediterranean and Black Sea dropped by 28 percent.


The third group comprises the FAO areas that FAO Statistical Areas showing an have shown a continual increase in catch since 1950 increasing trend in fish landings (Figure A5). There are only three areas in this group: Western Central Pacific (Area 71), Eastern (Area 57) and Western Indian Ocean (Area 51). They have contributed 26.4 percent of the total catch on average in the last five years. Minor drops in catch have also been seen in Western Central Pacific and Western Indian Ocean in the last two years. However, considering the uncertainty involved in catch reporting and natural fluctuation in fish stock abundance, such declines might have been caused by environmental “white noise” and need to be monitored over the next few years.


Major characteristics and significant changes
Fluctuations in the abundance of a fish stock are a common phenomenon, particularly for low-trophic-level species. As a result, the catch of this stock also usually oscillates in a similar manner. However, at a regional level, fluctuations in catch often appear to be less marked. This is because: (i) fish stocks within an ecosystem often compensate for one another as they increase and decrease in abundance; and (ii) aggregation over catches of all species usually smoothes out the variations of low-trophic-level and short-lived species. This is because the abundance and catch of high-trophic-level and long-lived species often vary less.

In the three groups defined above for analyzing overall catch trends, the first group – Eastern Central and Southwest Atlantic, and Southeast, Northeast and Eastern Central Pacific, and Northwest Pacific – had large fluctuations in landings (Figure A3). The largest fluctuation is seen in the Southeast Pacific (Area 87; Figure A3). A drop of about 10 million tonnes occurred between 1970 and 1973. The fish stocks then recovered and produced an all-time high catch of more than 20 million tonnes in 1994. The catch from this area dropped by 12 million tonnes again in the subsequent five years (between 1994 and 1998) and was at about 12 million tonnes in 2009, almost as high as its first peak in 1970. The large interannual variation in catch from the Southeast Pacific is caused by the large proportion of pelagic species in catches from the area. The top three species were anchoveta (Engraulis ringens), Chilean jack mackerel (Trachurus murphyi) and South American pilchard or sardine (Sardinops sagax); together, they account for more than 80 percent of the current and historical catches. They have had alternating periods of high and low abundance in recent decades. Large catch fluctuations are common in this region and are mostly a consequence of the periodic climatic events known as El Niño. El Niño events affect fishing success as well as longer-term stock abundance and productivity. These and other changes in fisheries production from Area 87 are described in further detail in Chapter B15 of this volume.

Significant fluctuations were also reported for other regions, although their combined effect on global catches was less noticeable. For example, in the Northeast Pacific (Area 67, Chapter B11), fish production reached a peak of 3.6 million tonnes in 1987 and declined to 2.2 million tonnes in 2009, following a slight recovery to 3.2 million tonnes in 2005 (Figure A3). The Northwest Pacific has shown an oscillation between 20 and 24 million tonnes since the late 1980s (Figure A3). The fluctuations were caused by catch and, presumably, abundance changes of Japanese pilchard or sardine (Sardinops melanostictus) and Alaska pollock (Theragra chalcogramma). These and other changes in total catch and state of resources are further described in Chapter B10.

In the Eastern Central Pacific (Area 77), described in Chapter B13, catches have fluctuated between 1.2 and 1.8 million tonnes since 1981 (Figure A3).The 2009 catch was at a peak of about 2 million tonnes, probably because of the recovery of California pilchard or sardine (Sardinops caeruleus). They yielded 0.8 million tonnes in 2009, an all-time record high and slightly higher than the high catch of 720 000 tonnes in 1936, which occurred during the previous high “regime” of this species. This previous peak period lasted from the late-1920s throughout the early-1940s. The total landings of the Southwest Atlantic (Chapter B6) have also fluctuated around 2 million tonnes since the late 1980s (Figure A3). Argentine hake, Argentine anchovy, Argentine short-fin squid and Argentine red shrimp are the species that show strong fluctuations in this area.

Temporal fluctuations in the landings of the second group (declining landings) are weaker (Figure A4). The landings from the Northeast Atlantic (Chapter B2) have continued the declining trend seen since the mid-1970s. This has mainly been caused by the decline in Atlantic cod (Gadus morhua) since the late 1960s, with a bounce back in the 1990s. It is noteworthy that landings of blue whiting (Micromesistius poutassou), which increased gradually since the 1970s and reached a peak of about 2 million tonnes in 2003, dropped back to below 1 million tonnes in 2009. Sandeels (Ammodytes spp.) also experienced a striking and marked drop to below 0.4 million tonnes in 2009 after peaking at more than 1.2 million tonnes in the mid-1990s.

In the Northwest Atlantic (Area 21), fish production declined to a low of 2 million tonnes in 1994 (Figure A4), following the collapse of groundfish stocks off eastern Canada. However, the catch has since stabilized at about 2 million tonnes. The collapse in Atlantic cod in the 1970s and of American plaice in the early 1990s has been balanced out by the increase in catches of low-trophic- level species such as American sea scallop and American lobster.

The Western Central Atlantic (Area 31), Mediterranean and Black Sea (Area 37) and Southwest Pacific (Area 81) have also experienced a period of declining catches, but to a lesser extent (Figure A4). Large reductions in catches have been seen in the last decade for round sardinella, ocean catfish NEI (not elsewhere included) and requiem sharks NEI in the Western Central Atlantic, and for mullets, blue whiting and common octopus in the Mediterranean and Black Sea, and for blue grenadier and oreo dories NEI in the Southwest Pacific.

Of the three areas showing a continuously increasing trend in catch, the West Indian Ocean (Area 51) and Western Central Pacific (Area 71) have shown some signs of decline in the last few years (Figure A5), though these may be natural fluctuations. When examining this trend at the species level, large declines are clear for skipjack and yellowfin tuna, and for natantian decapods NEI in the West Indian Ocean. However, decreases in those species were balanced out by increases in the catches of other redfishes, Indian oil sardine, and giant tiger prawn. Similarly, reductions in sharks, rays, skates etc NEI and in penaeid shrimps NEI, from these areas was compensated by an increase in skipjack tuna, threadfin breams NEI and natantian decapods NEI in the Western Central Pacific. Standing out from all other areas, the East Indian Ocean is the only FAO area that has not shown any sign of decline in total catch, and no clear decline in catch has been seen in major fish species (Chapter B9).

Tunas and tuna-like species are collectively the most valuable fishery resources exploited in the high seas. Their total production is highest in the Pacific Ocean followed by the Atlantic and Indian Oceans. As discussed in Chapter C1, catches of tuna and tuna-like species increased from less than 0.5 million tonnes in the early 1950s to an all-time high of 5.5 million tonnes in 2006. The catch has stabilized at about 5.4 million tonnes since 2003. Among the species, skipjack tuna (Katsuwonus pelamis) accounts for about 47 percent, at 2.6 million tonnes in 2009. Yellowfin tuna contributed 20 percent of the catch (1.1 million tonnes) followed by bigeye tuna at 7 percent (0.4 million tonnes) and kawakawa at 6 percent (0.3 million tonnes) in 2009.

Total recorded catches from deep-sea fisheries reached a peak of about 3.6 million tonnes in 2004 and then dropped back to 1.9 million tonnes in 2009 (Chapter C4). The Atlantic Ocean supports the largest deep-sea fishery, contributing about 80 percent of the total deep-sea catch between 2000 and 2005, followed by the Pacific Ocean and Indian Ocean. The dramatic decline can largely be attributed to the decrease in reported catches of blue whiting in the Atlantic Ocean. The catch of blue whiting decreased from 2.4 million tonnes in 2004 to about 65 000 tonnes in 2009, owing to a decline in recruitment, spawning stock biomass and a reduction of quotas (ICES, 2011). The species that have yielded a high average catch in the last five years (2005–09) in the Atlantic Ocean include Patagonian grenadier (Macruronus magellanicus), Greenland halibut (Reinhardtius hippoglossoides), southern blue whiting (Micromesistius australis) and ling (Molva molva).

The top five species are blue whiting (= poutassou), contributing 1.5 million tonnes in 2009 and accounting for 35 percent of the total catch of deep-sea fisheries, followed by hairtails and scabbardfishes NEI (135 000 tonnes, 7 percent), Patagonian grenadier (132 000 tonnes, 7 percent), blue grenadier (112 000 tonnes, 5 percent) and Greenland halibut (97 000 tonnes, 5 percent). Patagonian grenadier, Greenland halibut, blue grenadier, southern blue whiting, orange roughy, and oreo dories NEI have all experienced clear declines in catch.

A recurring pattern in some areas is the medium- to long-term change in catch composition following the decline of some fish stocks that had traditionally been dominant. For example, in the Northwest Atlantic (Chapter B1), catches of molluscs and crustaceans have increased noticeably following the declines of demersal fishes. In the Northeast Atlantic (Chapter B2) the reduction in catches from the continuous decline in Atlantic cod since the late 1960s has been balanced out by the increase in catches of formerly low-value species, such as blue whiting and sandeels. In the Northwest Pacific (Chapter B10), the decline in catches of Japanese pilchard or sardine and Alaska pollock has been somewhat offset by the increasing catches of Japanese anchovy (Engraulis japonicus), largehead hairtail (Trichiurus lepturus) and squids (mostly Todarodes pacificus). The causes for these medium- to long-term changes in the species composition of marine commercial catches can be multifold. These causes include adaptation of industry and markets to previously unattractive low-valued species, and the effect of fishing on the abundance of target species and on the structure of other marine communities. At the same time, environmental changes or regime shifts affecting the long-term abundance of the various wild fish stocks have occurred. Often, these effects are confounding and in many cases they are difficult to discern. This is particularly the case in areas where research and monitoring of fishery resources and environmental processes are not well developed.

Catch composition
Pelagic species comprise the largest proportion of the global marine catches. Small pelagics (ISSCAAP Group 35: herrings, sardines, anchovies, etc.) contributed about 22 percent (19.9 million tonnes) of the total catch in 2009 (Figure A6).


This share is down from 29 percent in the 1950s and 27 percent in 1970s. The large pelagics (ISSCAAP Groups 36 and 37: tunas, bonitos, billfishes and miscellaneous pelagics) accounted for 19 percent (16.6 million tonnes) of the total catches in 2009. This is an increase in their share from 13 percent in the 1950s. Demersal fishes (ISSCAAP Groups 31, 32 and 34: flounders, halibuts, soles, cods, hakes, haddocks and miscellaneous demersals) contributed 12 percent of the total catches in 2009 (10.9 million tonnes), compared with almost 26 percent in the 1950s and 1970s. Miscellaneous coastal fishes (ISSCAAP Group 33) increased slightly to 8 percent (7.2 million tonnes) from 7 percent in 2009. Catches of crustaceans (ISSCAAP Groups 42, 43, 44, 45, 46 and 47: crabs, lobsters, shrimps, prawns, krill, etc.) contributed 6 percent (5.4 million tonnes) in 2009, slightly lower than 7 percent in 2002. Molluscs (ISSCAAP Groups 52, 53, 54, 55, 56, 57 and 58: abalones, conchs, oysters, mussels, scallops, clams, squids, octopus, etc.) increased slightly from 6 percent in the 1950s and 1970s to 7 percent (6.2 million tonnes) in 2009. The proportion of unspecified fish (ISSCAAP Group 39) decreased slightly with 11 percent of the total catches (9.9 million tonnes) in 2009. In world fish production, pelagic – defined here as those belonging to ISSCAAP Groups 34–37 (following Grainger and Garcia [1996]) is defined to include jacks, mullets, sauries, herrings, sardines, anchovies, tunas, bonitos, billfishes, mackerels, snooks and cutlassfishes. Demersal species (ISSCAAP Groups 31–33 and 38) include flounders, halibuts, soles, cods, hakes, haddocks, redfishes, basses, congers, sharks, rays and chimaeras. These groups contributed similar proportions of total marine fisheries production in 1950, 41 percent and 35 percent, respectively. The remaining 24 percent of the total catch came from other species, including shrimps, prawns, crabs, clams, mussels, and marine fishes not identified. While the total marine fish landings increased with the development of the fishing industry, landings from demersal species reached, and in some cases exceeded, the limit of their potential production in the early 1970s. Subsequently, catches of demersal species levelled off below 20 million tonnes (Figure A7).

Production from pelagic species increased over time, with large fluctuations reflecting both natural variations in species productivity as well as boom and bust harvesting strategies. Production of pelagic species peaked at 40 million tonnes in the early 1990s that has been followed by a decreasing trend. The production of other species continued to increase until 2000 and has since stabilized at about 22 million tonnes. In 2009, pelagic, demersal and other species represented 46 percent, 24 percent, and 30 percent, respectively (Figure A7).


The distribution of landings among species is highly skewed. Among the 221 pelagic species recorded, the top ten were anchoveta, Atlantic herring, chub mackerel, Chilean jack mackerel, Japanese pilchard, South American pilchard, capelin, skipjack tuna, European pilchard (= sardine), and Japanese anchovy, in sequence of the average catch from 1950 to 2009. Together, they contributed about 50 percent of the total pelagic landings in 2009 and about 22.5 percent of total global landings. All the top ten pelagic species have experienced substantial declines in catch, except skipjack tuna (Figure A8). The most dramatic boom–bust catch patterns have been seen in Japanese pilchard, South American pilchard, and capelin. Their historical peak catches were 4–6 million tonnes, but were negligible in 2009. Peruvian anchovy has recorded the largest catches of pelagic species and demonstrated the most dramatic variations. It had a peak catch of 12 million tonnes in 1969, very low catches between 1970 and 1990, and resurging back to about 12 million tonnes in 1994, and was still 7 million tonnes in 2009. Skipjack tuna has been the only species that has shown a continuous growth in total catch, from 0.16 million tonnes in 1950 to 2.6 million tonnes in 2009. This is a 16-fold expansion in catch over this 59-year period.


For demersal species, the top ten species were Alaska pollock (= walleye pollock), Atlantic cod, largehead hairtail, blue whiting (= poutassou), sandeels (= sandlances) NEI, haddock, saithe (= pollock), Cape hakes, Atlantic redfishes NEI, and flatfishes NEI, ordered in terms of average annual landings from 1950 to 2009. In general, production of the top ten demersal species is not as high as that of pelagic species, nor do they exhibit variations in catch of the same extent. These ten species produced 37 percent of the total demersal landings in 2009 (Figure A9). The most common pattern across these ten species has been a decreasing trend in catch. Nine of the ten species produced a much lower catch in 2009 than their historical highs. Most of them had a peak catch in the 1960s or 1970s. Largehead hairtail is the only species that has not experienced a decline, but a levelling off in catch since the mid-1990s.

Species composition varies from area to area around the world. All the major species groups were represented more or less equally in the Northwest Pacific (Area 61) (Figure A10). Small pelagics (mostly anchoveta) dominate catches in the Southeast Pacific (Area 87). In the Northeast Atlantic (Area 27), demersal fishes were the most abundant, followed by larger pelagics and small pelagics. In the Western Central Pacific, catches were dominated by larger pelagics, which were also the most abundant group in the Western Indian Ocean (Area 51). Small pelagics were also dominant in the Eastern Central Atlantic (Area 34), Mediterranean and Black Sea (Area 37), Western Central Atlantic (Area 31) and Eastern Central Pacific (Area 77). In contrast, demersal fishes were the dominant species group in the Northeast Pacific (Area 67) and Southwest Pacific (Area 81).

STATE OF EXPLOITATION

Since its first publication of the global review of marine fish stocks in 1971 (Gulland, 1971), the FAO Fisheries and Aquaculture Department has been regularly assessing and monitoring the state of world marine fish resources. Assessment methodologies used in its reviews are described in Appendix. As explained there and in the last paragraph of this section, a modified approach has been adopted for this review. This includes the reduction of the number of categories of state of exploitation from five to three. A primary goal of this change has been an attempt to ensure greater standardization in the assessment methods between regions. At the same time, it also recognizes the large differences in the amount and quality of data and information available in different regions. This new method will probably have led to slight differences in the regional assessments of state of exploitation compared with the result that would have been obtained with the previously used approach. This could mean that the two approaches may not be directly comparable. However, this issue should not affect the aggregated global estimates. These should be comparable, taking into account the large uncertainties that are an unavoidable feature of any global assessment of the state of stocks.

The assessment data available to FAO in 2009 from the 17 FAO Statistical Areas plus the “Tuna” category has been summarized in Tables D1–D19. These tables address 584 “stock” items, of which 395 stocks were assessed in 2009, representing 70 percent of global catch. The remaining 189 stocks had either insufficient information for status assessment or catches with no proper identification, even at the family level, that was provided in official national statistics. Some species, even where properly identified in the official statistics, were not monitored or investigated because of the inadequacy of other data requirements. Species in this group usually correspond to less-abundant and lower-value species on which research effort tends to be limited. However, there are also some major stocks and fisheries with limited data, including stocks of mullets, mussels, shrimps and prawns in several areas, bonga shad (Ethmalosa fimbriata) and European anchovy (Engraulis encrasicolus) in the Eastern Central Atlantic, Pacific cod (Gadus macrocephalus) in the Northeast Pacific, and various newly exploited deep-sea resources.

FAO has always made efforts to standardize the number of marine stocks or species groups monitored and described for each major fishing area. However, the uneven availability of information and distribution of catch volumes have limited the number of stock groups able to be considered per area. In addition, in some parts of the world, there are relatively large numbers of stocks or species groups whose state of exploitation is undetermined or not known. The Western Indian Ocean (Area 51) and Western Central Atlantic (Area 31) are fishing areas with the highest incidence of stocks or species groups for which the state of exploitation is reported as not known or uncertain in the regional reviews presented in Part B of this paper.

With the development of world fisheries, both the assessment methods and the data available for such assessment have changed significantly. It is noteworthy that this review uses three categories: non-fully exploited, fully exploited and overexploited (Figure A11). This decision was made following recommendations from an external review panel on the FAO method and FAO’s internal review. It reflects the fact that the data currently available to FAO for most stocks do not provide sufficient information for the differentiation between recovery and depleted and between underfished and moderately exploited. The category of “fully exploited” represents stocks with an abundance that falls within a band around the level that can produce MSY. Provided these stocks are being carefully monitored and managed in a precautionary manner, this is a desirable status. In comparison with the five categories used in the previous assessments, the underfished and majority of the “moderately exploited” stocks have been merged and now roughly correspond to the new “non-fully exploited” category. Parts of the “moderately exploited” and “overexploited” stocks under the earlier approach may have been classified as “fully exploited” in this new approach and merged with those classified as “fully exploited” by both the old and new methods. Finally, both “depleted” and “recovering” stocks are merged into “overexploited” (for details, see Appendix 1).


Global stock status
Of the fish stocks assessed, 57.4 percent were estimated to be fully exploited in 2009. These stocks produced catches that were already at or very close to their maximum sustainable production. They have no room for further expansion in catch, and even some risk of decline if not properly managed. Among the remaining stocks, 29.9 percent were overexploited, and 12.7 percent non-fully exploited in 2009. The overexploited stocks produced lower yields than their biological and ecological potential. They require strict management plans to rebuild their stock abundance to restore full sustainable productivity. The World Summit on Sustainable Development (WSSD) goal demands that all these overfished stocks be restored to the level that can produce MSY by 2015. This review suggests that this goal is very unlikely to be achieved, notwithstanding the good progress made in some countries and regions (Worm et al., 2009). The non-fully exploited stocks were under relatively low fishing pressure and have a potential to increase their production. However, these stocks often do not have high production potential. The potential for increase in catch may be generally limited. Nevertheless, proper management plans should be established before increasing the exploitation rate of these non-fully exploited stocks in order to avoid following the same track of overfishing.
The proportion of non-fully exploited stocks has decreased gradually since 1974, when the first FAO assessment was accomplished (Figure A11). In contrast, the percentage of overfished stocks has since increased, especially in the late 1970s and 1980s from 10 percent in 1974 to 26 percent in 1989. After 1990, the number of overfished stocks continued to increase, but the rate of increase slowed, until the last two assessments, reaching about 30 percent in 2009. The fraction of fully exploited stocks demonstrated the smallest change over time. The percentage dropped from about 50 percent at the start of the series to 43 percent in 1987 and has increased to 57.4 percent in 2009 (Figure A11).
A primary fishery management goal is to control fishing at a level that allows the fishery to produce sustained annual yields. This yield should be as close to MSY as allowed by responsible management within the context of an ecosystem approach. This goal should lead to keeping the proportion of overexploited stocks at zero, as required by the WSSD goal set in 2002. At the same time, it allows for increasing exploitation rates on non-fully exploited stocks. This would maximize the sustained contribution of fisheries to global food security and human well-being. The increasing trend in fully exploited stocks after 1990 indicates the positive impact of fishery management towards maximizing production. However, close attention is required to all fully exploited stocks to ensure that they are not overexploited in the future. Moreover, the increase in overfished stocks is a cause for concern. It indicates that, at the global level, the WSSD targets for rebuilding the overfished stocks and implementing an ecosystem approach are not being met. Nevertheless, the deceleration in the rate of increase of overfished stocks after 1990 in comparison with the 1980s may indicate some progress in improved management. It suggests that some fi sh resources have benefited from the management efforts of coastal States and the international community.

Regional stock status
Development of the fishing industry and management of fishery resources vary with country and region. The Western and Eastern Central Atlantic (Areas 31 and 34) had the highest proportion of overfished stocks, about 54 percent in 2009 (Figure A12). The Southeast (Area47), Southwest Atlantic (Area41),and Mediterranean and Black Sea (Area 37) had 50 percent of fish stock overfished. The lowest proportion of overfished stocks was about 10 percent, seen in the Eastern Central Pacific (Area 77), Northeast Pacific (Area 67) and Southwest Pacific (Area 81). Other Areas had 15–30 percent of fish stocks overexploited (Figure A12).


In terms of potential for further expansion, the Eastern Central Pacific (Area 77) and Southern Oceans (Areas 48, 58 and 88) had the highest proportion of non-fully exploited stocks, about 38 percent in 2009 (Figure A12). However, these areas are not major fishery production areas and contributed only 2.3 percent and 0.2 percent of global catch, respectively, in 2009. The Southwest Pacific (Area 81) and Eastern Indian Ocean (Area 57) and Mediterranean and Black Sea had about 20 percent of stocks underexploited and may provide opportunities for further fishery expansion. All the remaining areas had a very low percentage of fish stocks that have room for expansion in catch.

Differences can also be found in stock status between pelagic and demersal fish stocks. Demersal stocks had the highest percentage of overfished stocks and the lowest proportion of non-fully exploited stocks, at 38 percent and 7 percent, respectively, in 2009 (Figure A13). In contrast, pelagic species had only 22 percent of stocks overfished, but 16 percent non-fully fished in 2009. The percentage of fully exploited species was 54 percent for demersal and 62 percent for pelagic. Overall, these percentages indicate that pelagic stocks are in better shape than demersal species, with more stocks being sustainably fi shed and fewer stocks overfished. The results seem associated with the biological and ecological characteristics of pelagic and demersal species and with the history of fishery development. The “Others” group had percentages for both overfished and non-fully fished stocks in between those for demersal and pelagic (Figure A13).

For the top ten pelagic species, 30 percent of stocks were estimated to be overfished in 2009, which is higher than the 20 percent for all pelagics (Figure A13). In contrast, the top ten demersal species had 43 percent of their stocks overfished, similar to the average for all demersal species. However, both pelagic and demersal top-ten groups had no underexploited stocks, which is not surprising as large stocks are more likely to become the target of fishing. They also attract more effort for management so that they have a greater percentage of stocks fully exploited. The above-average percentage of overfished stocks for the top ten pelagic species probably reflects the widespread risk of overfishing taking place even when there are good management systems in place. This is because of social and economic pressures to maintain catches even when they may exceed sustainable levels.


Tuna stock status
Tuna and tuna-like species have high commercial values and support fisheries of a global, multigear and multispecies nature. All the world’s tuna and tuna-like species are the subject of research and management by regional fisheries management organizations (RFMOs). There are five main tuna fishery management bodies: the Western and Central Pacific Fisheries Commission, the Inter-American Tropical Tuna Commission, the Indian Ocean Tuna Commission, the International Commission for the Conservation of Atlantic Tunas and the Commission for the Conservation of Southern Bluefin Tuna. Tuna RFMOs cover a large part of the world’s oceans, and they involve many countries. Tuna fisheries are characterized by high commercial value, global nature, and complex management. They involve many different types of stakeholders, and this frequently makes management scientifically and politically complex. International management of tuna and tuna-like species is governed by several legal instruments such as the binding UNCLOS, the UNFSA (UN, 1995) and the voluntary FAO Code of Conduct for Responsible Fisheries (the Code) (FAO, 1995a).

FAO has been monitoring the state of principal market tuna stocks as part of its initiative to assess the stock status of the world’s marine fishery resources. Principal market tunas include: albacore (Thunnus alalunga), Atlantic bluefin tuna (T. thynnus), bigeye tuna (T. obesus), Pacific bluefin tuna (T. orientalis), southern bluefin tuna (T. maccoyii), yellowfin tuna (T. albacares), and skipjack tuna (Katsuwonus pelamis). They represented about 80 percent of the total catch of tuna and tuna-like species in 2009. Because of their wide distributions, the state of each of these seven tuna species was assessed at the stock level, rather than by FAO Statistic Area as is done for other species. FAO’s classification is based on a variety of data and information including those from tuna RFMOs and may not necessarily be the same as those of the RFMOs.

The global annual catch of tuna and tuna-like species has shown an increasing trend from less than 1 million tonnes in 1950 to about 6.5 million tonnes in 2009. The global production of the principal market tunas increased relatively steadily from less than 0.5 million tonnes in the early 1950s to a maximum of about 4.4 million tonnes in 2005 and has since stabilized at this level (Chapter C1). In particular, catches of skipjack have continued to increase up to 2009. Albacore has shown a much weaker increasing trend since the 1970s, with greater interannual variations. In contrast, yellowfin, bigeye, Atlantic bluefin, Pacific bluefin and southern bluefin tunas have all shown a gradual decline in catch after reaching their historical peaks.

Among the seven major tuna species, one-third were estimated to be overfished in 2009, close to the 30 percent for all monitored stocks. Of the remainder, 37.5 percent were fully exploited and 29 percent non-fully exploited in 2009. This compares favourably with 57.5 percent and 12.7 percent of the global average.

Uncertainty
All stock assessments involve uncertainty, and uncertainty arises from three different sources: data, methods and the process of applying the methods to the data. Awareness of the degree of such uncertainty helps to understand the reliability of the results and their interpretation. In the 2009 assessment, the uncertainty of each assessment was scored according to one of three categories: “high”, “medium” and “low” (for more information, see Appendix 1). In general, the Northwest Atlantic (Area 21), tunas, Northeast Atlantic (Area 27), and Northeast Pacific (67) had the lowest uncertainty, with 80–96 percent of assessed stocks having low uncertainty. These were followed by the Eastern Central (34) and Southwest Atlantic (Area 41) and Mediterranean and Black Sea (Area 37) with about 63 percent of stocks having low uncertainty (Figure A14). In contrast, the Eastern Indian Ocean (Area 57) and Western Central Pacific (Area 71) have the highest uncertainty (84– 88 percent), with no stocks assessed as having low uncertainty about their status. This high uncertainty results from a combination of limited data available, the existence of many small stocks for many species and other complexities of assessment in tropical waters. The Southwest (Area 81), Southeast (Area 67) and Northwest Pacific (Area 61) also have a relatively high percentage of stocks for which the assessment was highly uncertain.

DISCUSSION

The total production of marine fishery resources has declined gradually after reaching a peak in landings in 1996. Is it possible to increase global fishery production any further? One way in which yields could be increased is to rebuild the 30 percent overfished stocks so that they can produce close to their MSY. This should lead to a net increase in landings. However, it is difficult to estimate the extent of this increase because it is not only related to the current abundance of overfished stocks but also depends on the biological and technical interactions between species. Nevertheless, the top ten demersal species have 43 percent of stocks overfished. As a result, their 2009 production was only 51 percent of their peak level. This may give some indication of the scale of catch loss caused by overfishing. However, better estimates of the lost production will require a combination of stock assessments and ecosystem modelling. A second approach for increasing global production would be to intensify exploitation of the non-fully exploited stocks (13 percent of the monitored stocks). To avoid the same pattern of overfishing that has been experienced with other species in the past, any attempt to intensify exploitation on non-fully exploited stocks should be accompanied by precautionary management plans.

This updated assessment suggests that the state of global marine fish stocks is continuing along its historical trend. There has been a slow but apparently ongoing increase in the proportion of overexploited stocks and a decreasing percentage of non-fully exploited stocks, while the number of fully exploited stocks has increased slightly. However, it must also be noted that progress is being made in some regions, which should serve both as encouragement and as examples of successful management. For example, the number of stocks classified as overfished and/or subject to overfishing showed a fall in Australia from 24 in 2005 to 18 in 2008 (Wilson et al., 2009). Fisheries in large marine ecosystems such as the California Current and the Eastern Bering Sea have reduced exploitation rates and rebuilt biomass to or above the level that produces multispecies MSY (Worm et al., 2009).

Of the three categories describing stock status, the percentage of overfished stocks is the one of greatest concern. Not only can overexploitation cause negative ecological consequences, it can also reduce fish production with resulting negative social and economic consequences (World Bank and FAO, 2009). The need to improve management of stocks is widely recognized. The WSSD set a target to restore all overfished stocks to the level that can produce maximum sustainable yield by 2015. The strategic goal of the 2010 Conference of the Parties to the Convention on Biological Diversity is: “by 2020 all fish and invertebrate stocks and aquatic plants are managed and harvested sustainably, legally and applying ecosystem approaches” (UNEP, 2010). The UN Millennium Development Goals (UN, 2010) is also monitoring the proportion of fish stocks within “safe” biological limits as an indicator of environmental sustainability. The successful cases highlighted above demonstrate that effective management is possible. Member States, the general international community and all relevant stakeholders need to work together to achieve the agreed goals.

Assessing stock status usually requires quantitative analysis either through modelling or monitoring key indicators. Catch data alone are often insufficient, although they may allow the use of catch-only methods. It is a common practice in fisheries that stock assessment is undertaken to provide the information necessary for designing management regulations. This is still true, even when they may range from qualitative to quantitative assessments. However, assessment results are not always available to the public. The RAM Legacy Database compiled the results of classic assessments on 234 stocks of 124 species that accounted for about 20 percent of global catch (Branch et al., 2011). FAO has adopted a spectrum of methods and extended the coverage to 70 percent of the global catch. There is still 30 percent of the global catch without any formal assessment. This is mainly because these catches are taken from stocks or species groups with insufficient information to assess their state of exploitation. Moreover, within the above, there is a high proportion of the total marine catch without reliable information on what species are being caught. This catch was recorded in the FAO database as “miscellaneous fishes” or “marine fish NEI”. These landings are termed here as the “NEI” group, and the share of global catch statistics attributed to this group increased to 33 percent in 2009 (Figure A15). Assessing stock status for the “NEI” group is often difficult, although not completely impossible. Therefore, greater effort needs to be made at all levels and stages of fisheries research and management. These actions should range from improving the identification of species being caught and landed to improving the information base for the proper assessment of fish stocks as required by the Code. This code requires that “States should ensure that timely, complete and reliable statistics on catch and fishing effort are collected and maintained in accordance with applicable international standards and practices and in sufficient detail to allow sound statistical analysis” (Article 7.4).

SOURCE OF INFORMATION

Marine and Inland Fisheries Service, Fisheries and Aquaculture Resources Use and Conservation Division. FAO Fisheries and Aquaculture Department “Review of the state of world marine fishery resources” FAO FISHERIES AND AQUACULTURE TECHNICAL PAPER. No. 569. Rome, FAO. 2011.

BIBLIOGRAPHY
The bibliographic references are available through the hyperlink displayed in "Source of Information".

Acknowledgements
We wish to thank all the authors in Section B - the regional reviews of marine fisheries resources in FAO statistical areas for their contribution to the data and information presented in this chapter. We are also grateful to Luca Garibaldi and Fabio Carocci for their input in the preparation of data and graphs. Finally, David Milton and Jacek Majkowski are thanked for their valuable comments and suggestions to an earlier version of this manuscript.