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3. Status of resources


The management of fishery resources in the Asia-Pacific region needs to be improved as overfishing is increasing and the abundance of the more valuable species has declined. In this review, we first look at a number of the major seas of the region to determine the degree to which ecosystems have been impacted by fishing, and the situation in terms of serial depletion of key major groups in the ecosystem. Evidence is derived from two sources - trawl surveys carried out throughout the region and catches by major groups of the region's Large Marine Ecosystems (LMEs).

In inland waters, most fisheries are small-scale activities where the catch per capita is relatively small and used mainly for subsistence purposes. The lack of accurate reporting of these small-scale fisheries makes it difficult to describe their status but it is generally felt that they are under considerable pressure from loss and degradation of habitat and overfishing.

Marine waters

3.1 Measuring the status of fishery resources

Traditionally, the status of capture fisheries has been described by (i) providing a summary of the time series trends in production for a fishery or region and (ii) presenting an assessment based on the number of fisheries or stocks categorized as being under-exploited, fully exploited or over-exploited (e.g. SOFIA[18]). However, in many seas of the APFIC region, such descriptions are not sufficient and may in fact be misleading. Reporting total production often masks what is actually happening in the fishery, and both of the above indicators also rely on the existence of accurate and timely fishery statistics from all the sub-sectors of the fishery, including small-scale fisheries. Calculating the percentages in terms of exploitation also relies on having reliable stock assessments, at least for the more abundant fish stocks in a fishery. In the APFIC region characterized by multi-species/multi-gear fisheries, it is very rare to find a fishery satisfying the above two conditions.

Pauly and his co-workers at the University of British Columbia (UBC), Canada have been advocating a more ecosystem-based approach to the assessment of fisheries - the so-called "fishing down the food chain[19]" approach. The basic concept of this is presented in Figure 25.

This approach is based on a hypothetical fishery in which industrial-scale fishing (mainly bottom trawling, purse seining and long-lining) expanded in the 1950s and 1960s. The catches in the earlier stages of this development were dominated by large longer-lived predators. As these became fished down, fishers expanded their efforts moving further away from their home base and starting to take smaller, less predatory fish. During this period, total production from the fishery can be expected to be maintained, masking the serial depletion that is occurring. Most alarming is that throughout this period, the total amount of fish in the ocean is continually declining and the catch rates of the major groups are also declining as they, in turn, become overexploited.

3.2 Evidence from trawl surveys

Biomass analyses

The WorldFish Centre (WFC) has recently prepared a number of papers on the status of fisheries from eight APFIC States (Bangladesh, India, Indonesia, Malaysia, the Philippines, Sri Lanka, Thailand and Viet Nam). These analyses are based on trawl survey data, spanning the period 1920 to the present (Trawlbase)[20] and the coverage of surveys is shown in Figure 26.

Overall, analyses of the trawl surveys showed substantive degradation and overfishing of coastal stocks. For trawl surveys where there were more than 25 years between surveys, the amount of fish (measured as tonnes/km2) had declined to between 6 and 33 percent of the original value. In all cases, the amount of fish had declined, some as much as 40 percent in 5 years. The most dramatic declines were in the Gulf of Thailand and the East coast of Malaysia. Two examples, one for the Gulf of Thailand and one for Manila Bay are given in Figure 27.

Figure 25
"Fishing down the food chain"
A hypothetical model of the impact of fishing on a marine ecosystem

Figure 26
Trawl surveys in the Asian region
From Silvestre, G. T., Garces, L. R., Stobutzki, I., Ahmed, M., Santos, R. A. V., Luna, C.Z. and Zhou, W. (2003). South and Southeast Asian coastal fisheries: Their status and directions for improved management. Conference Synopsis and recommendations, p. 1-40 in Silvestre, G.T., Garces, L.R., Stobutzki, I., Ahmed, M., Santos, R.A.V., Luna, C.Z., Lachica-Alino, L., Christensen, V., Pauly, D. and Munro (eds.) Assessment, Management and Future Directions for Coastal Fisheries in Asian Countries. WorldFish Centre Conference Proceedings 67, 1 120 pp.

The massive decline in the amount of fisheries resources available for today's fishers has also been associated with changes in the composition of the catch. Surveys in the Gulf of Thailand and in the Lingayen Gulf in the Philippines have shown that the abundance of larger, more valuable species (e.g. groupers, snappers, sharks and rays) higher up in the food chain have declined, while smaller species lower in the food chain (e.g. triggerfish, cardinal fish and squids/octopus) have increased to relative abundance. In the Gulf of Thailand trawl survey catch in the 1960s, the top 10 species (or species groups) were made up of rays, bream, goatfish with some squid, lizard fish and snapper (Figure 28). By contrast in the mid-1990s, less desirable pony fish, squid, barracuda, and lizard fish had become much more prevalent.

The Trawlbase survey study enabled an estimation of the exploitation rate for 427 stocks in the region. With the exception of the coast of Brunei Darussalam, where fishing pressure is less intense, the majority of stocks were being fished at levels above the recommended optimum range.

Ecosystem modelling

A new approach to fishery assessment is emerging, and in the case of the eight States with extensive trawl survey data, facilitated by having good estimates on the amount of fish present in the sea. This approach is based on ecosystem modelling (e.g. Ecopath and Ecosim) that allows an analysis of the structure and function of whole ecosystems and how they have changed over time. Christensen and his coworkers at the UBC are pioneering the approach and have recently concluded an analysis of the impact of fishing in the South China Sea[21]. This analysis clearly showed that for this large sea, "fishing down the food chain" has occurred, indicating gradual replacement of large, long-lived predators by small, short-lived fish lower down the food chain, often referred to now as "trash fish". The only exception to these trends was off the coast of Brunei Darussalaen where fishing pressure is much lighter than in other States, since it effectively has marine protected areas (MPAs) around its oil rigs.

Socio-economic assessments

As part of the analyses of historical trawl data, the WFC also carried out some in-depth socio-economic assessments of the eight participating States. This profiling allowed an assessment of the importance of coastal fisheries in terms of earnings, employment, trade and nutrition and their contribution to the economy. The profitability of fishing operations in Malaysia, Thailand and Viet Nam was studied, and broken down to several sub-sectors.

In general, it was shown that fishing is still a profitable enterprise in all three States, particularly for the owners of industrial fishing vessels. Owners of industrial craft and gear earn large profits (up to 30 percent per year) while artisanal, small-scale fishers often have an extremely marginal livelihood. Unfortunately, industrial fishing employs few crew and provides little opportunity for unemployed or under-employed small-scale fishers. Even within small-scale fisheries, benefits are not evenly distributed. The loss in revenue and profits associated with overfishing were demonstrated using the Gulf of Thailand as an example (Table 11). Based on 1995-1996 data, large rent dissipation and excess capacity (in both labour and capital) can be clearly seen. Similar analyses have been done for the Philippines and other areas in the past.

These analyses of trawl survey data are continuing and the available results all point to substantive degradation and biological overfishing in most of the survey areas spread across South Asia and Southeast Asia. The amount of fish now available for the region's fishers is only a small percentage of that originally available before the rapid escalation of industrial fishing.

3.3 Evidence from Large Marine Ecosystems

Trends across Large Marine Ecosystems

In this analysis, the trends in catch composition for the major Large Marine Ecosystems of the APFIC region were examined. LMEs are relatively large regions (200 000 km2 or more) characterized by distinct bathymetry, hydrography, productivity, and trophically dependent populations. Their seaward limit usually extends beyond the continental shelf. Being defined by natural parameters, they most often straddle political boundaries. They have been identified for the purpose of comprehensive monitoring and could also be used as a basis for ecosystem-based management of shared natural resources in the future. To date, 63 LMEs have been described world wide with 20 of these being in the APFIC region (Figure 29).

Figure 27
Declines in the abundance of fish in (i) Manila Bay and (ii) Gulf of Thailand as measured by trawl surveys. From same source as Figure 26

Figure 28
Changes in the composition of the top ten species taken from trawl survey catches in the Gulf of Thailand between 1966 and 1995. Data from same source as Figure 26

Table 11
Comparison of catch, revenues, costs and profits at different levels of fishing effort (MSY = maximum sustainable yield; MEY = maximum economic yield). From same source as Figure 26

State of fishery

Effort
(std. hr x 106)

Catch
(Tonnes x 103)

Revenue
(Baht x 106)

Costs
(Baht x 106)

Profit
(Baht x 106)

MSY

28.57

985

6578

1992

4586

MEY

21.75

952

6359

1517

4842

Open access

62.70

654

4372

4372

0

Actual (1995)

56.88

728

4862

3966

896

Much of the information referred to here has been taken from the NOAA website, which acknowledges sources of information and has an extensive reference list[22], as well as an analysis of the FAO catch database as modified by the University of British Columbia[23].

The Asia-Pacific region is characterized by considerable diversity in LMEs in terms of their fisheries and driving forces (Table 12). The most productive (total recorded catch since 1950) are the East China Sea, the Kuroshio Current and the South China Sea. Following closely behind, are the Yellow Sea, the Sea of Japan, the NW Pacific high seas area, and the Bay of Bengal.

The Indonesian Sea, the Gulf of Thailand and the Sulu-Celebes Seas are clustered in another group, followed by the much smaller catches in New Zealand and Australia.

An interesting feature of many of the LMEs is the dominance of a small number of small pelagic and benthopelagic species in the landings (in terms of weight). The major species are the South American pilchard (Sardinops sagax), chub mackerel (Scomber japonicus) and the largehead hairtail (Triciurus lepturus) in the Kuroshio Current, Sea of Japan, Yellow Sea, East China Sea, and the South China Sea. In the Bay of Bengal, Arabian Gulf, Sulu-Celebes Seas, Indonesian Sea, and NW Australia, anchovies (Stolephorus spp. and Engraulidae) form a large part of the catch with other small pelagic species such as the sardine (Sardinella spp.) common in some areas. Pacific saury (Colobis saira) has formed a large part of the catch in the high seas of the NW Pacific.

Exceptions to this pattern are the heavily trawled areas of the Gulf of Thailand and Northern Australia where more demersals, threadfin breams and shrimps, respectively, are taken, although even in these areas catches of anchovies are almost as high as the demersal catches.

Trends in selected Large Marine Ecosystems

There are obviously numerous ways that the LMEs can be classified but for the purpose of this review they are grouped as follows:

i. Offshore deepwater systems dominated by pelagic fishes (e.g. Kuroshio Current and NW Pacific);

ii. Heavily fished coastal systems that display sequential depletion of species groups characteristic of "fishing down the food chain" (e.g. Yellow Sea, Gulf of Thailand and NW Australia);

iii. Coastal systems that are still showing increasing reported catches (e.g. Bay of Bengal and South China Sea); and

iv. Fisheries managed under tight access right control (e.g. South East Australia and New Zealand Shelf).

These examples have been analysed in some detail below.

i) Offshore deepwater pelagic systems

Kuroshio Current

The Kuroshio Current LME is dominated by the warm Kuroshio Current that flows in a northeasterly direction along Japan's east coast. This LME has a huge latitudinal expanse, providing it with a rich variety of marine habitats. The region has a generally mild, temperate climate. The underwater topography of the LME includes the Japan Trench, the Shatsky Rise, the Ryukyu Trench and the Okinawa Trough.

The Kuroshio Current LME is considered a moderately high (150-300 gC/m2/yr) productivity ecosystem with coastal areas that are highly productive. Japan and China are the major fishing nations in the region. The fish catch includes Japanese sardine, Pacific saury, anchovy, jack mackerel, horse mackerel, frigate mackerel, yellowtail, filefish, herring, sea robin, and parrot bass (Figure 30). The sardine population, which is characteristic of small pelagic fish populations, has shown marked fluctuations, attaining an all time maximum in the 1930s, then showing a decrease from 1964 to 1971. It has since increased. With the fluctuations there have been accompanying geographic shifts of spawning and nursery grounds. As is the case in the Sea of Japan, the system has always been dominated by small to mid-sized pelagics, with a more recent trend to large pelagics.

Figure 29
Large Marine Ecosystems of the APFIC Region
1. Sea of Japan; 2. Kuroshiro Current; 3. Yellow Sea; 4. East China Sea; 5. South China Sea; 6. Bay of Bengal; 7. Gulf of Thailand; 8. Arabian Sea; 9. Sulu-Celebes Seas; 10. Indonesian Sea; 11. Western-Central Pacific; 12. Pacific Hawaiian; 13. N Australia; 14. NW Australia; 15. W Australia; 16. NE Australia; 17. E Australia; 18. SW Australia; 19. SE Australia; and 20. New Zealand

Table 12
The large marine ecosystems of the Asia-Pacific region (excluding W Australia, E Australia, NE Australia and SW Australia)

LME

Fishery

Trends

Driving Force (s)

Sea of Japan

Mixed

  1. Small pelagics
  2. Large bentho-pelagics

Demersals peaked in 1970s
Small pelagics peaked in mid-1980s
Large bentho-pelagics peaked in early 1970s
Recent increase in squid, large pelagics, lobsters and crabs

Climate
Fishing
Habitat
Pollution

Kuroshio Current

  1. Small pelagics
  2. Pelagics

Small pelagics and pelagics peaked in mid-1980s

Climate

Yellow Sea

Mixed

  1. Large bentho-pelagics
  2. Small pelagics
  3. Shrimp
  4. Pelagics

Small pelagics peaked in late 1970s and early 1990s
Large bentho-pelagics leveled off in early 1970s
Recent increase in pelagics and small demersals

Climate
Fishing
Habitat
Pollution

East China Sea

Mixed

  1. Small pelagics
  2. Small demersals
  3. Large bentho-pelagics

Small pelagics peaked in late 1980s
Small demersals peaked in late 1960s and again in late 1990s
Shrimp increasing

Fishing
Pollution
Habitat
Climate

South China Sea

Mixed

  1. Small pelagics
  2. Pelagics
  3. Large bentho-pelagics
  4. Demersals

Increasing trends in all groups up until late 1990s
Pelagics still increasing

Fishing
Pollution
Habitat

Bay of Bengal

Mixed

  1. Pelagics
  2. Small pelagics
  3. Small demersals
  4. Shrimp

All groups increasing

Fishing
Pollution
Habitat

Gulf of Thailand

Mixed

  1. Demersals
  2. Pelagics
  3. Small pelagics
  4. Shrimp

Demersals peaked in early 1970s followed by a sudden decline during
1980s and 1990s
Pelagics peaked in early 1970s
Small pelagics fluctuating annually
Pelagics peaked in early 1970s


Arabian Sea

Mixed

  1. Pelagics
  2. Small demersals
  3. Shrimp
  4. Medium bentho-pelagics

Pelagics stable since mid-1980s but increasing recently
Small demersals and shrimp increasing until recently
Bentho-pelagics stable

Fishing
Pollution
Habitat

Sulu-Celebes Sea

Mixed

  1. Small pelagics
  2. Pelagics
  3. Demersals
  4. Large pelagics

Small pelagics increasing with annual fluctuations
Pelagics peaked in late 1980s
Large demersals peaked in late 1950s
Demersals peaked in 1970s and late 1990s
Large pelagics stable since early 1990s

Fishing
Pollution
Habitat

Indonesian Sea

Mixed

  1. Pelagic
  2. Small pelagics
  3. Large pelagics
  4. Demersals

Pelagics peaked in late 1980s but stable since early 1990s
Small pelagics still increasing
Large pelagics showed rapid growth during 1990s but declined over recent years
Demersals peaked late 1990s

Fishing
Pollution
Habitat

Western-Central Pacific

Mixed

  1. Small pelagics
  2. Cephalopods
  3. Large pelagics

Small pelagic catches cyclical
Cephalopods slowly increasing
Large pelagics stable with annual fluctuations
Flatfish peaked in late 1950s
Demersals peaked in late 1980s

Climate
Fishing

Insular Pacific Hawaiien

Mixed

  1. Small pelagics
  2. Demersals
  3. Molluscs
  4. Large pelagics

Small pelagics cyclical peaking in late 1950s and late 1980s
Demersals peaked in mid-1980s
Molluscs peaked in late 1960s, early 1970s
Large pelagics declining since late 1980s

Climate
Fishing
Habitat

N Australia

Mixed

  1. Shrimp
  2. Large pelagics
  3. Small demersals

Shrimp catches cyclical
Large pelagics peaked in late 1980s
Demersals peaked in early 1970s and early 1990s

Climate
Fishing

NW Australia

Mixed

  1. Small demersals
  2. Pelagics
  3. Small pelagics
  4. Shrimp

Small demersals peaked in early 1970s and early 1990s
Pelagics peaked in mid-1990s
Small pelagics increasing
Shrimp catches stable

Fishing
Habitat

SE Australia

Mixed

  1. Small pelagics
  2. Molluscs
  3. Lobsters, crabs

Small pelagics peaked in early 1990s
Molluscs peaked in early 1970s and mid-1980s
Lobster, crab catches steady

Climate
Fishing
Pollution
Habitat

New Zealand shelf

Mixed

  1. Large demersals
  2. Large bentho-pelagics
  3. Small bentho-pelagics

Large demersals cyclical but stable since 1990
Large bentho-pelagics cyclical but relatively stable
Small bentho-pelagics peaked in late 1980s

Climate
Fishing
Pollution
Habitat

Western and Central Pacific

The Western Pacific Warm Pool is one of the 56 biogeochemical province defined by Longhurst[24]. The Pool is a zone of low productivity which can extend over a range of 80º of longitude (nearly 8 000 km) and has the warmest surface waters in the world. The Warm Pool can undergo spectacular east-west displacements of up to 400 km as part of the El Niño/La Nina cycle.

The current status of fisheries in the South Pacific was recently reviewed by APFIC[25]. The fisheries catch was divided into oceanic resources that include tunas, billfish that live in the open-water pelagic habitat and coastal fisheries. The offshore resources form the basis of the regions industrialized fisheries and have been fished by an international fleet from 26 different nations over the past 25 years - 15 Pacific Island States and 11 distant-water fishing nations with the bulk of the catch being taken by Japan, USA, Korea RO, and China PR. About 1.6 million tonnes of tuna, as well as an unknown amount of by-catch have been taken from the Western and Central Pacific each year during the 1990s. The main species are skipjack (the majority of which is taken by purse seiners), yellowfin and bigeye tuna (an increasing catch associated with drifting fish attracting devices), and albacore (caught by long-line and trolling with a significant part taken by Pacific Island States) (Figure 31).

The coastal resources include a wide range of fin-fish and invertebrates and form the basis for the region's small-scale fisheries. Although dwarfed in both volume and value by the oceanic tuna fisheries, the regions coastal fisheries provide most of the non-imported fish supplies to the region and have a crucial role in food security. The present catch figures are roughly estimated based on agriculture censuses, household surveys or nutrition studies. The best estimate available is about 144 000 tonnes, with about 70 percent of this coming from subsistence fisheries, which despite their importance do not attract much government attention, although anecdotal reports of their depletion in many islands are common. Major species include finfish, beche-de-mer (sea cucumbers), octopus, lobsters, giant clams, crabs and seaweed. Several high-value products are exported from the region. In a recent World Bank study, coastal fisheries management was examined at 31 locations in the Pacific Islands. The study concluded that there was an urgent need to reduce overall fishing effort. Although many of the communities had adopted restrictions to fishing by outsiders, few were effectively regulating their own harvest.

ii) Ecosystems with "fishing down the food chain" effects

Yellow Sea

The Yellow Sea LME is a semi-enclosed body of water bounded by the Chinese mainland to the west, the Korean Peninsula to the east, and a line running from the north bank of the mouth of the Yangtze River (Chang Jiang) to the south side of Cheju Island. It covers an area of about 400 000 km2 and measures about 1 000 km by 700 km. It is shallow with a mean depth of 44 meters, and it slopes gently from the Chinese continent. The Yellow Sea LME is classified as highly productive (>300 gC/m2/yr) ecosystem. It has marked seasonal variations and supports substantial populations of fish, invertebrates, marine mammals, and seabirds. It has both cold temperate species (eel-pout, cod, flatfish, Pacific herring) and warm water species (skates, gurnard, jewfish, small yellow croaker, spotted sardine, fleshy shrimp, southern rough shrimp) (Figure 32).

With its 276 fish species, the Yellow Sea LME is an important global resource for coastal and offshore fisheries. However, it is one of the most intensively exploited areas in the world, and has exhibited a pronounced change in ecosystem structure and "fishing down the food chain" effect. Due to overexploitation and natural fluctuations in recruitment, some of the larger-sized and commercially important species were replaced by smaller, less valuable, forage fish. When bottom trawlers were introduced in the early twentieth century, many stocks were intensively exploited by Chinese, Korean, and Japanese fishers and all the major stocks were heavily fished in the 1960s, which had a significant effect on the ecosystem. Pacific herring and chub mackerel became dominant in the 1970s. Smaller-bodied and economically less profitable anchovy and scaled sardine increased in the 1980s and took a prominent position in the ecosystem. Cold-water species such as the Pacific cod (Gadus macrocephalus) are almost extinct. It appears fishing has greatly affected both the structure and functioning of the Yellow Sea ecosystem.

Figure 30
Reported landings from the Kuroshio Current LME

Figure 31
Reported landings from Western and Central Pacific

Figure 32
Reported landings from the Yellow Sea LME

Gulf of Thailand

The Gulf of Thailand LME is a semi-enclosed sea immediately to the northwest of the South China Sea LME from which it is separated by two sills. Monsoon seasons and the intrusion of sea water from the South China Sea are the two natural phenomena that seem to drive the LME and are the major causes of oceanographic change in the absence of any massive regime shift. The Gulf of Thailand is relatively shallow, with depths varying between 45 and 80 meters. The LME is considered as being a highly productive (>300 gC/m2/yr) ecosystem. Its high primary production levels are partly the result of increased nutrient loading from rivers and shrimp farms. Primary production is concentrated in coastal areas between Malaysia and Cambodia, and near Viet Nam.

The commercial species found on the shallow Gulf of Thailand consist of crabs, lobsters, rays, sharks and small pelagics (mainly Indian mackerels (Rastrelliger spp.), anchovies, and stolephorus spp.), originally caught by artisanal fishers and supplying local markets (Figure 33). Most important among these are the anchovies used for making fish sauce. In the 1960s, demersal trawl gear was introduced from Germany (as trialed in the Philippines), which led to the development of a Thai demersal trawl fishery, operating in the shallow grounds bordering Thailand's coasts. The ecological impact of the increase in trawling effort has been well documented and was used to describe the original "fishing down the food chain" phenomenon. The catch composition changed both within species (toward smaller individuals), and between species (toward a mix consisting predominantly of small, short-lived species). The species groups most adversely affected by trawl fisheries were crabs, lobsters, rays, sharks and other large fishes. Studies of the impact of the various fishing gears operating in the Gulf of Thailand demonstrate that these fisheries have fundamentally altered, and continue to alter, the functioning of that ecosystem. However, even in this extreme case, modelling has shown that the impact still appears to be reversible although a drastic reduction of fishing effort, especially by bottom trawlers and push-netters would be needed to replenish these stocks and halt further ecological degradation of this LME.

Northwest Australian shelf

The Northwest Australia LME extends from Northwest Cape in the State of Western Australia to the vicinity of the Timor Sea. The LME has a wide continental shelf and it includes topographical features such as the Exmouth Plateau, the Rowley Shelf and the Sahul Shelf. The tropical waters are warm, and the coast includes reefs and extensive mangrove forests. Tropical cyclones are common seasonal events in this LME. It is considered to be a low productivity (<150 gC/m2/yr) ecosystem. The warm tropical waters are the home of corals, fish, starfish, sponges, turtles and shells.

In the Northwest Australia LME, fish stocks are quite small and the level of endemicity is low, with most species distributed widely in the Indo-West Pacific region. Reef fisheries occur in the Rowley Shoals, a chain of coral atolls at the edge of the LME's wide continental shelf. Demersal species that are fished here include snapper, beam, emperors and lizard fish (Figure 34). These have historically been fished by foreign fleets that caused widespread habitat destruction with an associated decline in the demersal fish catch and a switch to smaller, less valuable fish. A large part of the area is now closed to pair trawlers and access to foreign fleets has been withdrawn, and there is some evidence that the habitat is recovering. A small domestic trap fishery for demersal fish exists in areas subjected to little trawling. It is thought that there will be an expansion of trap fishing in the two closed areas after the species composition changes induced by trawling are reversed.

iii) Systems with reported increasing catches

Bay of Bengal

The Bay of Bengal LME is located in the tropical monsoon belt and is bounded by Bangladesh, India, Indonesia, Malaysia, Maldives, Myanmar, Sri Lanka and Thailand. The Bay's southern part merges into the Indian Ocean. The LME is strongly affected by monsoons, storm surges, and cyclones. Major rivers (Ganga-Brahmaputra-Meghna, Mahanadi, Godavari, Krishna and Salween) introduce large quantities of silt into the Bay of Bengal during the monsoon season from July to September. The Bay of Bengal LME is considered to be moderately productive (150-300 gC/m2/yr).

Commercial species include anchovies, croakers, shrimp and tuna (yellowfin, big eye and skipjack). Shrimp is a major export earner. FAO data show a steady rise in total landings in all major groups since the 1950s (Figure 35). Heavy fishing is a comparatively recent phenomenon, so that stocks have not been subjected to fishing pressure over a lengthy period of time but there is now increased competition and conflicts between small-scale and large-scale fishers. There is an alarming increase in cyanide fishing in this LME's coral reefs for the lucrative live food fish markets in Hong Kong and Singapore. Mangroves and estuaries - critical fish spawning and nursery areas - are also under stress or threatened by pollution, sedimentation, dams for flood control (as in Bangladesh), and intensive coastal aquaculture. States bordering the Bay of Bengal rate overexploitation of marine resources as the number one problem in the area.

Figure 33
Reported landings from the Gulf of Thailand LME

Figure 34
Reported landings from the Northwest Australian Shelf LME

Figure 35
Reported landings from the Bay of Bengal LME

South China Sea

The South China Sea LME is bounded by the coasts of Viet Nam, China PR, Taiwan POC, the Philippines, Malaysia, Thailand, Indonesia and Cambodia. It is separated from the Gulf of Thailand to the West, by a shallow sill. The South China Sea contains many biological subsystems and a variety of habitats. These include mangrove forests, seagrass beds, coral reefs and soft-bottom communities. The 50-meter depth contour largely follows the coast, with the widest shelves occurring along the eastern edge of the LME. Much of the South China Sea is below 200 meters with oceanic waters, ranging in depth from 200 to 4 000 meters, covering nearly half of the Sea.

It is considered a moderately high productivity (150-300 gC/m2/yr) ecosystem. High productivity levels are found in gulfs, along the coast, and in reef and seagrass areas, common in the Philippines portion of the LME. The coastal and estuarine areas off Viet Nam, China PR and Cambodia are very productive and, in the past, a substantial fraction of the catch was taken by artisanal, non-mechanized boats. The Viet Nam/China PR area was lightly exploited from the mid-1970s to the mid-1980s, but by now much of this potential has probably been realized.

The total fish harvest was approximately 5.0 million tonnes a year in 2001, with an increasing trend until very recently (Figure 36). Although catches were apparently increasing for all trophic level groups, ecosystem modelling has shown that this area has also been subjected to "fishing down the food chain". Five of the States fishing this LME are among the top eight shrimp producers of the world. Fishermen sometimes use small-meshed nets and practice destructive fishing methods, such as cyanide and dynamite fishing.

In deep oceanic waters (200 to 4 000 m), fisheries are limited mainly to large pelagic fishes - tuna with some billfish, swordfish, shark, porpoise, mackerel, flying fish and anglerfish. The deeper coralline areas and those situated in the central portion of the LME are only lightly exploited, leaving room for a possible increase in catch from this area, although the resources are probably rather limited.

iv) Fisheries under tight management control

Southeast Australian Shelf

The Southeast Australia LME extends from Cape Howe, at the southern end of the state of New South Wales, to the estuary of the Murray-Darling river system in the state of South Australia. It borders the Southern Ocean and the western boundary currents flowing into the West Wind Drift, which circulates around the continent of Antarctica. It contains the island of Tasmania and Bass Strait, which separates that island from the state of Victoria on the mainland. The LME has a diversity of habitats such as seagrass beds, mud flats, intertidal and sub-tidal rocky reefs, mangrove forests and pelagic systems. It has been classified as a highly productive (>300 gC/m2/yr) ecosystem, despite the low nutrient input into the area.

Some of the species harvested are scallops (in Bass Strait), rock lobster (Tasmania), and abalone (Tasmania and Victoria) and finfish in the Southeast trawl fishery. The long-standing trawl fishery has seen serial depletion of several of its important fish stocks, including eastern gemfish and more recently the deepwater orange roughy that is found associated with sea mounts (Figure 37). The fishery has been managed under individual transferable catch quotas (ITQ) since the early 1990s, but to date, these do not appear to have been very effective in reducing overfishing in this multi-species fishery.

New Zealand shelf

The New Zealand Shelf LME surrounds the islands of New Zealand and stretches across 30 degrees of latitude from the sub-tropics in the north down to the sub-Antarctic region. The shelf surrounding New Zealand varies in width from 150 km in the northeast and southwest, to 3 000 km on the northwest and southeast plateaus. The northern half of the LME is influenced by the warm South Equatorial Current, while the southern half is influenced by the cooler West Wind Drift. The marine environment is diverse and includes estuaries, mudflats, mangroves, seagrass and kelp beds, reefs, seamount communities and deep sea trenches. The New Zealand Shelf LME is considered to be a moderately high (150-300 gC/m2/yr) productivity ecosystem.

Figure 36
Reported landings from the South China Sea LME

Figure 37
Reported landings from the Southeast Australian Shelf LME

Figure 38
Reported landings from the New Zealand Shelf LME

Maori cultural ties with fisheries are strong and their fishing rights are recognized in law. Fishing is a popular leisure activity for as many as one in five New Zealanders. Among the important commercial fisheries of the area are those for migratory predators such as tuna, billfish, and sharks. There is also a bottom fishery for the orange roughy, an important blue grenadier fishery and a coastal fishery for a variety of crustaceans and mollusks (Figure 38). The fishing industry is mostly export-oriented. All fisheries are managed under an ITQ system, that the NZ government claims has resulted in sustainable fisheries. Prior to the introduction of the system, overfishing of coastal resources had occurred. There are conflicting reports on the extent to which these have recovered, although there is evidence that certain groups, such as lobsters are responding to the new management regimes. As in Australia, the long-lived deepwater species such as orange roughy have continued to decline, offset by the discovery of new stocks and expansion in fishing. Other important stocks, such as the blue grenadier appear to be fished sustainably at present.

Inland waters

3.4 Water resources

Asia is blessed with the most freshwater in the world, estimated at 13 510 km3. However, because of the high population density, the per capita availability of freshwater is the lowest and competing usages of freshwater has a major impact on fisheries. The main water resources for fisheries are the rivers and flood plains, natural lakes and man-made impoundments. Asia has the largest number (49) of rivers than any other continent and also has the highest cumulative river channel length. The seasonal floodplains of States such as Myanmar and Bangladesh all have major fisheries. In contrast, Asia has relatively few natural lakes. Most of these are confined to volcanic areas, notably in the Indonesian and Philippine archipelagos, and in northern India. The major exception is the Great Lake or Tonle Sap in Cambodia which occupies 200-300 km2 in the dry season, expanding to 10 000-12 000 km2 in the wet.

Reservoirs have been constructed over many centuries in some States in Asia, (e.g. Sri Lanka), but more recently, construction of reservoirs for irrigation, hydropower and flood protection has become common in many parts of the Asia-Pacific region. These come in many forms ranging from large impoundments resulting from damming major rivers to small rain-fed ponds. The reservoir resource in Asia is large and accounts for over 40 percent of the global large reservoir capacity. It has been estimated that developing States in Asia have 66.7 million ha of small to medium reservoirs with 85 thousand ha occurring in China.

3.5 Fishery resources

Most inland fisheries are small-scale activities where the catch per craft (or catch per capita) is relatively small and the catch more often than not disposed of on the same day. The main exceptions are the industrialized fisheries in the lower Mekong Basin and the "fishing lots" in the Tonle Sap of Cambodia and the fishing "inns" of Myanmar. The lack of accurate reporting of these small-scale fisheries makes it difficult to describe their status but it is generally felt that they are under considerable pressure from loss and degradation of habitat and overfishing. Freshwater fishes are reported to be the most threatened group of vertebrates harvested by man. The World Resources Institute estimated that half of the World's species were lost during the last century and that dams, diversions and canals have fragmented many major rivers, severely impacting fisheries resources.

In general, the reported catches of inland fisheries in most States have continued to increase, although many of the inland water habitats have been altered and degraded. Rivers and floodplains, in particular, have been heavily impacted with the construction of dams, roads, channels and other irrigation systems. The training of water to reduce the impacts of flooding has probably had widespread effects on inland fisheries in the region, although the real impacts are poorly documented. Fishers regularly complain that catches are declining, but it is uncertain to what extent this is an effect of increasing fishery pressure or the loss of fishery resources through habitat degradation and changing water flow regimes.

In some areas, the way the systems function has been altered enormously by greatly reducing the seasonal "flood pulse" that previously resulted in large areas of land becoming flooded during the wet season. This in turn has impacted on the ability of many species of fish to migrate to their spawning grounds and has also altered the flow pattern with accompanied habitat changes (e.g. running water to lakes). Some mitigation attempts have been made in terms of fish ladders to allow fish to migrate around dams but their success compared with original conditions is typically unknown.

Changing agricultural cropping patterns, irrigation development and the increased use of chemicals and pesticides in intensified agricultural production have all had some impact on wild fishery resources. Changing rural livelihoods have also led people away from their traditional dependence on fishery resources as livestock has supplanted wild resources.

As in the marine environment, changes in species composition are also occurring. Catches of large, long lived species such as the giant catfish and large cyprinid species are becoming rare and there is evidence of "fishing down the food chain" in some inland areas. In the Mekong River, for example, the giant catfish (Pangasianodon gigas) has now become extremely rare and endangered. On the other hand, the status of some inland fishery resources has been enhanced through stocking programmes, introductions of exotic species, habitat engineering and habitat improvement.

Stock enhancement is an integral part of most inland fisheries in the Asia-Pacific region. With developments in artificial propagation techniques of fast-growing and desirable species and increased availability of seed stock, the use of this intervention is increasing, particularly where some sort of access restriction or user rights is in place. The economic viability of stock enhancement in large lakes and rivers has not been demonstrated in any Asian State and, in general, these fisheries depend naturally on recruited stocks. In floodplain depressions and in small water bodies, stock enhancement has proved to be very successful. These cultured-based fisheries are seen as a way forward in China PR and many States in the region.

Of particular importance to many States of the Asia-Pacific region are rice-field fisheries that either depend on natural introduction of wild fish or stocking fish, either simultaneously or alternately with the rice crop (probably more correctly defined as aquaculture). This aquatic production, in addition to the rice crop itself, is important for rural livelihoods in developing States. Its local consumption and marketing are particularly important for food security as it is the most readily available, reliable and cheapest source of animal protein for farming communities as well as the landless. This importance is generally underestimated and undervalued. It is reported that the availability of this aquatic resource is declining. Anecdotal evidence from China, Viet Nam, Lao PDR, Cambodia, Thailand and elsewhere, suggests that it is considerably more difficult to find such food now than a decade or so ago. This is a result of increasing demand through human population increases and activities such as the use of pesticides, destruction of fish breeding grounds and the use of illegal fishing methods such as poisons and electro-fishing.


[18] FAO (2000) The state of world fisheries and aquaculture. Food and Agriculture Organization of the United Nations, Rome, 142 pp.
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