Sprachen:
The source document for this Digest states:
The global state of exploitation of the world marine fishery resources has tended to vary, with some trends in the observed exploitation categories (Figure 20). While the proportion of underexploited or moderately exploited stocks declined linearly from 40 percent in the mid-1970s to 20 percent in 2007, the proportion of fully exploited stocks remained steady at about 50 percent. The proportion of overexploited, depleted or recovering stocks appears to have stabilized at between 25 and 30 percent since the mid-1990s (Figure 21). The overall examination of the state of stocks and groups of stocks for which information is available confirms that the proportions of overexploited, depleted and recovering stocks have remained relatively stable in the last 10–15 years, after the noticeable increasing trends observed in the 1970s and 1980s. It is estimated that, in 2007, about one-fifth of the stock groups monitored by FAO were underexploited (2 percent) or moderately exploited (18 percent) and could perhaps produce more. Slightly more than half of the stocks (52 percent) were fully exploited and, therefore, producing catches at or close to their maximum sustainable limits, with no room for further expansion. The other 28 percent were either overexploited (19 percent), depleted (8 percent) or recovering from depletion (1 percent) and, thus, yielding less than their maximum potential owing to excess fishing pressure in the past, with no possibilities in the short or medium term of further expansion and with an increased risk of further declines and a need for rebuilding.
Most of the stocks of the top ten species, which account in total for about 30 percent of the world marine capture fisheries production in terms of quantity (Figure 6 on page 12), are fully exploited or overexploited and, therefore, cannot be expected to produce major increases in catches. This is the case for: anchoveta (Engraulis ringens), with two main stocks in the Southeast Pacific that are fully exploited and overexploited; Alaska pollock (Theragra chalcogramma), which is fully exploited in the North Pacific; blue whiting (Micromesistius poutassou), which is fully exploited in the Northeast Atlantic; Atlantic herring (Clupea harengus), with several stocks that are fully exploited, some that are depleted and some that are underexploited because of market conditions; Japanese anchovy (Engraulis japonicus), which is fully exploited in the Northeast Pacific; Chilean jack mackerel (Trachurus murphyi), which is fully exploited and overexploited in the Southeast Pacific; and yellowfin tuna (Thunnus albacares), which is fully exploited in the Atlantic and Pacific Oceans and probably moderately to fully exploited in the Indian Ocean. Some stocks of skipjack tuna (Katsuwonus pelamis) are fully exploited while some are still reported as moderately exploited, particularly in the Pacific and Indian Oceans, where they could offer some limited possibilities for further expansion of fisheries production. However, this may not be desirable as it is nearly impossible to increase skipjack catches without negatively affecting bigeye and yellowfin tunas. Some limited possibilities for expansion are also offered by a few stocks of chub mackerel (Scomber japonicus), which are moderately exploited in the Eastern Pacific, while other stocks are already fully exploited. The largehead hairtail (Trichiurus lepturus) is considered overexploited in the main fishing area in the Northwest Pacific, but its state of exploitation is unknown elsewhere.
The percentage of stocks fully exploited, overexploited or depleted varies greatly by area. The major fishing areas with the highest proportions (71−80 percent) of fully exploited stocks are the Northeast Atlantic, Western Indian Ocean and Northwest Pacific. The proportion of overexploited, depleted and recovering stocks varies between 20 and 52 percent in all areas except in the Northwest Pacific, Western Central Pacific and Eastern Central Pacific, where it is 10 percent or less. Relatively high proportions (20 percent or more) of underexploited or moderately exploited stocks can be found in the Eastern Indian Ocean, Western Central Pacific, Eastern Central Pacific, Southwest Pacific and Southern Ocean, and for some species of tunas.
Four FAO major fishing areas account for more than 10 percent each and collectively produced about 66 percent of the world marine catches in 2006. The Northwest Pacific is the most productive, with a total catch of 21.6 million tonnes (26 percent of total marine catches), followed by the Southeast Pacific, with a total catch of 12.0 million tonnes (15 percent), the Western Central Pacific with 11.2 million tonnes (14 percent) and the Northeast Atlantic, with 9.1 million tonnes (11 percent).
In the Northwest Pacific, small pelagics are the most abundant category, with the Japanese anchovy providing large catches, although there were signs of decline in 2005 and 2006 as compared with catches of more than 2 million tonnes in 2003. Other important contributors to the total catch are the largehead hairtail, considered overexploited, and the Alaska pollock and chub mackerel, both considered fully exploited. Squids, cuttlefish and octopuses are important species yielding 1.4 million tonnes.
In the Southeast Pacific, total catches have oscillated around 12 million tonnes in the last five years. There has been no major change in the status of stocks since 2004. The stock of anchoveta has recovered from the severe El Niño event of 1997–98 and is considered fully exploited in most of the area. Two other important pelagic stocks, the Chilean jack mackerel and in particular the South American pilchard, remain in a decadal cycle of natural low abundance, producing a fraction of the record catches observed between the mid-1980s and mid-1990s. The stocks of South Pacific hake remain under heavy fishing pressure with no sign of recovery.
The Western Central Pacific is the most productive fishing area of the tropical regions, with total catches up about 3 percent on 2004. Tunas and tuna-like species make up about 24 percent of the total for this fishing area, with most species assessed as either fully exploited or moderately to fully exploited. The status of other species groups is highly uncertain. This region is highly diverse, its fisheries are mostly multispecies, and detailed data for reliable assessments are usually not available for most stocks. Analysis of survey information for some countries in the region (Malaysia, the Philippines, Thailand and Viet Nam) have shown considerable degradation and overfishing of coastal stocks, most dramatically in the Gulf of Thailand and along the east coast of Malaysia.
In the Northeast Atlantic, catches of blue whiting have stabilized at about 2 million tonnes per year since 2003, and the stock is considered fully exploited. Fishing mortality has been reduced in cod, sole and plaice. Cod remains depleted in the North Sea and in the Faeroes, but other stocks are healthier and considered fully exploited. Several stocks of haddock have shown spectacular increases in biomass since 2000, fisheries have grown and most stocks are now considered fully exploited. Saithe stocks have also increased since 2000. Some sand eel and capelin stocks have become depleted, while fishing for shrimp seems to have ceased in some areas.
A record high has been reached in total landings in the Eastern Indian Ocean, with a total of 5.8 million tonnes, a 5-percent increase compared with 2004. The category “marine fishes non-identified”, representing 50 percent of the total catches in the area, accounts for most of this increase. “Miscellaneous pelagic fishes” (including Indian mackerels and various carangids) made up 11 percent of the catches and “miscellaneous coastal fishes” (croakers, ponyfishes, sea catfishes, etc.) 10 percent. Tuna catches in 2006 were slightly below the six-year (2000–05) average of 450 000 tonnes. While catches of most groups show either a rising trend or are fluctuating slightly with no clear trend, there are indications that parts of this fishing area could be overfished, with the situation being aggravated by increasing stress from pollution, sedimentation, modified river runoffs and intensive coastal aquaculture.
There have been several changes in the status of the stocks in the Southeast Atlantic since the last full assessment made in 2004. The important hake resources remain fully exploited to overexploited although there are signs of some recovery in the deepwater hake stock (Merluccius paradoxus) off South Africa. The status of the coastal fishes remains fully exploited or depleted. A significant change concerns the Southern African pilchard, which was at a very high biomass and estimated to be fully exploited in 2004, but which now, under unfavourable environmental conditions, has declined considerably in abundance and is overexploited throughout the region. In contrast, the status of Southern African anchovy has improved from fully exploited to fully to moderately exploited, and Whitehead’s round herring is underexploited to moderately exploited. The condition of Cape horse mackerel has deteriorated, particularly off Namibia, where it is currently overexploited. The condition of the Perlemoen abalone stock has deteriorated, driven heavily by illegal fishing, and it is currently overfished and probably depleted.
Source & ©: FAO Fisheries – The State of World Fisheries and Aquaculture, 2008
PART 1:World review of fisheries and aquaculture, The Status of
fishery resources, p. 30-35
The source document for this Digest states:
Overall, 80 percent of the 523 selected world fish stocks for which assessment information is available are reported as fully exploited or overexploited (or depleted and recovering from depletion). It should be noted that the status of fully exploited is not undesirable provided it is the result of an effective and precautionary management approach. Nevertheless, the combined percentage reinforces earlier observations that the maximum wild capture fisheries potential from the world’s oceans has probably been reached. Therefore, a more cautious and closely controlled approach to development and management of world fisheries is still required (Box 2). As reported in The State of World Fisheries and Aquaculture 2006, the situation seems more critical for some highly migratory, straddling and other fishery resources that are exploited solely or partially in the high seas. An example highlighted in that earlier edition included the state of highly migratory oceanic sharks, with more than half of the stocks for which information is available being listed as overexploited or depleted. In the case of straddling stocks and of other high seas fishery resources, nearly two-thirds of the stocks for which the state of exploitation can be determined were classified as overexploited or depleted. These high seas fishery resources constitute only a small fraction of the world fishery resources, but they can be considered key indicators of the state of a major part of the ocean ecosystem. The United Nations Fish Stocks Agreement entered into force in 2001. It is providing a legal basis for management measures that are now being introduced and that are expected to benefit species fished on the high seas in the medium to long term. However, further rapid progress in implementation is necessary if the ocean ecosystem is to be safeguarded.
Source & ©: FAO Fisheries – The State of World Fisheries and Aquaculture, 2008
PART 1:World review of fisheries and aquaculture, The Status of
fishery resources, p. 34-35
The source document for this Digest states:
Box 2: Reconciling conservation with fisheries
Is there a future for capture fisheries if we are to conserve aquatic ecosystems? Conversely, is there a future for capture fisheries if we do not conserve ecosystems? Can the social and economic goals of fishing be reconciled with the goal of conserving aquatic ecosystems? While in some arenas, fisheries and conservation may be seen as incompatible activities, it is widely recognized that both are fundamental elements of sustainable development. Capture fisheries are responsible for a significant share of the food supply for human consumption. They provide jobs and income for millions of people worldwide and have an important role in the economies of many countries (see Part 1 of this publication). Ensuring that the species and ecosystems that support these fisheries are maintained in healthy and productive states – in other words, that they are conserved – is essential if such benefits are to be sustained into the future.
Despite its social and economic importance, attempts to manage fisheries sustainably have been unsuccessful in many parts of the world due to several factors. 1 These management failures have given rise to widespread concerns, often accompanied by high-profile media reports, about the negative impacts of fisheries on marine ecosystems. In the eyes of many environmentalists and of public opinion in general, the overfishing of stocks, habitat modification resulting from destructive fishing practices, the incidental capture of endangered species and other impacts have made fisheries a primary culprit in an ecological crisis of global dimensions. While some of the claims have been exaggerated and some misleading, the underlying crisis is real and an urgent response is required at global level. However, in responding, there is a danger that the pendulum will swing too far in the opposite direction and, from an overemphasis on short-term social and economic goals, the long-term goals of conservation will become the only driving forces in the management of human impacts on aquatic ecosystems.
Many solutions to the ecological crisis have been proposed, including among them the banning of certain fishing practices, control of access to fisheries by global implementation of systems of access rights, greater use of positive incentives, regulation of trade in endangered species (e.g. through the Convention on International Trade in Endangered Species of Wild Fauna and Flora, known as CITES) and the establishment of marine protected areas. All of these have roles to play in reconciling fisheries and conservation, but none of them would provide the solution if used in isolation. There is now broad agreement at the international policy level that the ecosystem approach to fisheries (EAF) is the appropriate and necessary framework for fisheries management. The EAF, which flows from and is consistent with the FAO Code of Conduct for Responsible Fisheries, is defined as an approach that “strives to balance diverse societal objectives, by taking into account the knowledge and uncertainties of biotic, abiotic and human components of ecosystems and their interactions and applying an integrated approach to fisheries within ecologically meaningful boundaries”. It addresses both human and ecological well-being and merges two paradigms – that of protecting and conserving ecosystems and that of fisheries management, which focuses on providing food, income and livelihoods in a sustainable manner.
If, as is now widely recognized, the unsustainable use of aquatic ecosystems has its roots in ill-functioning institutions and communities, it is only to be expected that any solution to conservation will have to be: (i) socially acceptable and just; (ii) effective from both biodiversity and livelihood perspectives; and (iii) based on strengthened institutions at local and international levels. Therefore, the expanded objectives of the EAF will almost invariably require a diverse and comprehensive set of management tools in order to achieve the reconciled set of often conflicting goals. A common understanding of the concept is developing, and good progress has been made in incorporating the principles of EAF in policies at international and national levels. However, there is still much to do to make these principles operational in the practical management of fisheries.
1 FAO. 2002. Report and documentation of the international workshop on factors contributing to unsustainability and overexploitation in fisheries. Bangkok, Thailand, 4–8 February 2002, edited by D. Greboval. FAO Fisheries Report No. 672. Rome.
Source & ©: FAO Fisheries – The State of World Fisheries and Aquaculture, 2008
PART 1:World review of fisheries and aquaculture, The Status of
fishery resources, Box 2, p. 36-37
The source document for this Digest states:
By landing more than 10 million tonnes in 2006, inland fisheries contributed 11 percent of global capture fisheries production. Although the amount may be small in comparison with marine fisheries, fish and other aquatic animals from inland waters remain essential and irreplaceable elements in the diets of both rural and urban people in much of the world, especially in developing countries. However, for demographic and cultural reasons, there are significant differences in the level of exploitation among the major geographical regions. Although global landings from inland fisheries have grown continuously, there are few examples of collapsing fisheries and a number of fish stocks, especially in Latin America, remain lightly exploited. Therefore, adopting a precautionary approach, the fisheries could be developed further.
Although statistics are improving in some countries, collecting accurate information on inland fisheries can be extremely costly. Moreover, many public administrations still do not collect such information or make assessments of the status of inland fishery resources. The very nature of inland fisheries makes assessment of their status extremely difficult. In addition, inland fisheries practised for sustenance or gain often take place in remote areas and are carried out by the poorer sectors of society. Catches are frequently not recorded by species or not recorded at all. Catch statistics are generally inadequate for use as a measure of stock status. Therefore, providing accurate statements on the status of inland fishery resources on a global or even regional level remains a challenge. Noting this and in order to enhance knowledge and awareness of the sector, FAO invited case studies of a number of inland fisheries in various parts of the world. 12 These studies were also meant to highlight some of the most crucial issues in ensuring the sustainability of such fisheries.
The five case studies presented below all confirm that inland fisheries are highly complex, and that, where ecosystem processes remain largely undisturbed, stock dynamics are basically controlled by environmental processes and factors external to the fisheries, such as natural fluctuations in climate or flood patterns. Often, the yields track intra-annual and interannual variations in nutrient inputs (whether natural or resulting from pollution), although response times depend on the life cycle of the fish. Therefore, the perception that fishing pressure is the only or main driver is mistaken; and fish stock assessments based on steady-state assumptions can be highly misleading, both in the interpretation of trends and in the use of fishery assessment models.
However, anthropogenic ecosystem impacts in the form of species introductions, pollution, habitat fragmentation and changes in the flood cycle reduce the resilience of fish stocks to fishing pressure, and the fisheries should be managed with this in mind.
That said, there are considerable opportunities to safeguard and enhance existing inland fisheries that provide food security for millions of people and to realize the potential for developing underexploited stocks. It is crucial that inland fisheries be integrated in natural resources management plans that cover all stakeholders who affect the quality or quantity of the water resources throughout the catchment basin concerned. Inland fisheries management needs an ecosystem approach, and this is particularly important in large catchment areas for large lakes and river systems. The values and benefits of inland fisheries would be increased and strengthened if these fisheries were recognized and protected through better governance and political will.
Africa – Lake Victoria
Lake Victoria, shared between Kenya, Uganda and the United Republic of Tanzania, is the second-largest lake in the world, covering an area of 68 000 km2. In the mid-1980s, the lake’s fish community and fishery changed drastically from being dominated by more than 200 endemic haplochromine species to a catch of basically three species: the introduced Nile perch (Lates niloticus) and dagaa/omena (Rastrineobola argentea) in the open waters; and the introduced Nile tilapia (Oreochromis niloticus) along the shores (Figure 22). The endemic cichlids (haplochromines), that vanished almost completely as the fish community changed, have been reappearing in catches since 2000 and are probably recovering slowly. The inshore demersal species, originally mainly endemic tilapias (Oreochromis esculentus, O. leucosticus and O. variabilis), Nile catfish (Bagrus docmac), lungfish (Protopterus aethiopicus), the elephant-snout fish (Mormyrus kanume), and the ningu (Labeo victorianus), are all depleted, except the lungfish. Today, the Nile tilapia dominates, its abundance is increasing in surveys and it is considered moderately exploited. Dagaa stocks and catches have been increasing steadily. Since 2005, it has been the most important fishery in the lake by weight, but there are no signs of overexploitation. The economically most important Nile perch fishery supports an export industry worth some US$250 million per year. The status of this stock is controversial, but while many believe it is overfished, there are no objective data to support this claim.
A recent analysis13 has shown that the dynamics of fish production in Lake Victoria are, to a large extent, environmentally driven. Changes in land-use practices have led to an increased input of nutrients, resulting in a doubling in primary production since 1969, and providing the basis for the observed increase in fish production. However, eutrophication has also led to increases in fish kills and loss of habitat owing to deoxygenation. This poses a serious threat to the entire ecosystem.
Central Asia – Kyrgyzstan
The disintegration of the Soviet Union had a profound impact on the fisheries sector throughout Central Asia. Kyrgyzstan was one of the countries most severely affected. In 2004–06, its capture fisheries yield had dropped to only 3 percent of the level recorded in the early 1990s (Figure 23). All exploited fish stocks are in serious decline. In 2005, the naked osman (Gymnodiptychus dybowskii) and Issyk Kul marinka (Schizothorax pseudoaksaiensis issykkuli), two species that constituted an important part of the catch in the past, were recommended for inclusion in the Red Book of Kyrgyzstan.
Most lakes in the country are oligotrophic with low fisheries yields. Therefore, since the 1930s, in an attempt to boost productivity, most lakes in the country have been intensively stocked with mainly exotic species, including also several predators. This has placed indigenous species under stress. In addition, illegal fishing is a serious problem – illegal catches are estimated to be several times higher than official catches. Fishing concessions have now been leased out to private entities, but short-term lease contracts have discouraged sustainable management of the resources. The authorities are addressing the issue, and the collapse of the fishery has led to a moratorium on fishing in the country’s two largest lakes. However, recovery in the fish stocks is a long-term process and will depend on the implementation of new management measures.
Europe – Lake Constance
Lake Constance, shared by Austria, Germany and Switzerland, serves as a reservoir of potable water for more than 4 million people but also has an active fishery. Catch statistics have been collected on commercial fisheries since 1910, and yield statistics on angling since 1996. In 2006, about 140 commercial fishers caught 617 tonnes, of which about 80 percent was whitefish (Coregonus lavaretus). Some 5 000 anglers caught 68 tonnes, mainly perch (Perca fluviatilis).
Until the 1960s, the oligotrophic lake supported a whitefish-dominated fishery. However, increasing eutrophication led to higher fish production but also changed catch composition. There was a drastic decline in whitefish yields, down to 20–30 percent of the total catch, while perch yields increased to about 50 percent at the time when the lake was most eutrophied (Figure 24).
In the last 30 years, intensive measures to reduce eutrophication have re-instated the lake’s former oligotrophic state, reducing the total catch to the level before eutrophication while restoring the whitefish fishery, which again contributes about 80 percent of the annual yield.
At present, whitefish and perch populations are fully exploited. Nearly all the individuals that can be caught by the gillnets allowed are taken. All other target species are only moderately exploited. Fishery management will need to adjust to lower yields, and the number of professional fishers may have to decrease further to ensure catches that will provide fishers with sufficient income.
Latin America – Amazon
The Amazon Basin covers 6.8 million km2 and is shared by Bolivia, Brazil, Colombia Ecuador, Guyana, Peru and Venezuela (Bolivarian Republic of). The commercial capture fisheries in the Brazilian part of the basin are the most significant, contributing up to 17 percent14 of total annual aquatic animal production in Brazil between 1996 and 2006. In that decade, the yield from these fisheries increased by 37 percent (Figure 25).
Most fish stocks (60 percent) are considered to be underexploited, while 30 percent are overexploited or recovering, including several large, slow-growing species such as tambaqui (Colossoma macropomum) and surubim (Pseudoplatystoma spp.) (Figure 26). Several medium-sized species including jaraqui (Semaprochilodus spp.) and curimatã (Prochilodus nigricans) are also showing signs of overfishing. The data on exploitation levels need to be interpreted with caution because environmental factors such as flood intensity overshadow the impact of the fishery, particularly for species with opportunistic life strategies and short life spans. High fishing pressure in combination with weak recruitment caused by unfavourable environmental conditions may lead to collapse. On the positive side, stocks of pirarucu (Arapaima gigas) and the large migratory catfish piramutaba (Brachyplatystoma vailantii) are now recovering. In the case of pirarucu, which became commercially extinct in the 1970s and completely disappeared in some areas, recovery can be related to the introduction of new community-based management practices.
Southeast Asia – Tonle Sap
The Mekong River Basin, shared by Cambodia, China, the Lao People’s Democratic Republic, Myanmar, Thailand and Viet Nam, sustains the largest inland fisheries in the world, with an estimated annual catch of 2.6 million tonnes 15. Contrary to popular belief, available data indicate that catches in the basin are larger than ever before. However, as the number of fishers is growing faster than the yield, the catch per fisher is declining.
The dai16 fishery in the Tonle Sap River (a Cambodian tributary of the Mekong River) has been monitored since 1995. More than 200 species are known from the river, but this fishery is dominated by a small number of opportunistic cyprinids maturing at a small size (r-selected species), which in most years account for more than half of the catch (Figure 27). As these species are short-lived, they are recruited to the fisheries the year they hatch or the following year. When favourable conditions occur, which in general terms means a larger flood, 17 yield increases immediately. While the response time is longer for longer-living species, the same pattern can be seen for these, although they are also affected by other factors (including fishing mortality). While historical catch data indicate that larger and slower-growing species are less abundant than in the past, nothing in the available dataset points to any species being overexploited. Whether any population decline can be attributed to increased fishing pressure or a deteriorating environment (pollution, water abstraction, dam construction and flood protection) is debatable. However, habitat destruction and fragmentation as a consequence of dam construction are currently larger threats than fishing pressure to fish stocks.
12 The five case studies were: Status and trends of the fishery resources of Lake Constance (by R. Rösch); Status and trends of the Lake Victoria fisheries (by J. Kolding and O. Mkumbo); Status and trends of the fishery resources of the Amazon Basin in Brazil (by M.L. Ruffino); the Tonle Sap fishery (based on data provided by the Inland Fisheries Research and Development Institute (Cambodia) and the Mekong River Commission; and Review of the fisheries of Kyrgyzstan (produced under project GCP/GLO/162/EC). FAO intends to publish the five case studies in full.
13 J. Kolding, P. van Zwieten, O. Mkumbo, G. Silsbe and R. Hecky. 2008. Are the Lake Victoria fisheries threatened by exploitation or eutrophication? Towards an ecosystem based approach to management. In G. Bianchi and H.R. Skjoldal, eds. The ecosystem approach to fisheries. (in press). CABI Publishing.
14 If the estuarine fisheries are included, Amazon landings in the last decade averaged 23 percent.
15 Estimate based on consumption surveys (K.G. Hortle. 2007. Consumption and the yield of fish and other aquatic animals from the Lower Mekong Basin. MRC Technical Paper No. 16. Vientiane, Mekong River Commission). Most fish is caught by subsistence fisheries, but large commercial fisheries also take place, particularly in Cambodia and Viet Nam.
16 A dai is a bagnet or a stationary trawl.
17 A larger inundated area increases both fish habitat and availability of food.
Source & ©: FAO Fisheries – The State of World Fisheries and Aquaculture, 2008
PART 1:World review of fisheries and aquaculture, The Status of
fishery resources, p. 35-41
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