An introduction to the oceanography, geology, biogeography, and fisheries of the tropical and subtropical western and central Pacific

Tags: Southeast Asia, Australia, Western Central Pacific, Central Pacific, Pacific Plate, Indo-Pacific, Eurasian Plate, South Pacific Islands, taxonomic diversity, wind patterns, Indian-Australian Plate, lithospheric plates, Southeast Asian, Springer, Oxford Univ. Press, glacial periods, New York, South Equatorial Current, Western Pacific, tropical western Pacific, South Pacific Commission, Living Marine Resources, geological events, Western Central Pacific Fig., primary productivity, Equatorial Currents, Hawaiian Islands, North Equatorial Current, the Pacific, trade winds, FAO Fisheries Yearbook, South Pacific Commission Area, R. Hall, FAO, WCP, Univ. California Press, pp, Asia, biogeography, Fisheries Research and Development Corporation, Pacific ocean, continental shelves, Audley-Charles, FAO Yearbook, Tectonic evolution of Southeast Asia, Pacific oceans
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An Introduction to the Oceanography, Geology, Biogeography, and Fisheries of the Tropical and Subtropical Western and Central Pacific
by K.E. Carpenter
Introduction The coverage of this identification guide is remarkable both in terms of the area encompassed and the diversity of marine resources. FAO Fishing Area 71 includes large maritime portions of 3 major geopolitical entities: most of Southeast Asia, the northeastern quadrant of Australia, and the South Pacific islands. For this guide, we expand coverage beyond Fishing Area 71 to include all of the fishing grounds covered by the South Pacific Commission (Fig. 1). The area covered is diverse culturally, politically, and geographically, and includes 32 countries and territories (Fig. 2), 14 major seas and gulfs, and numerous island chains (Fig. 3). In terms of longitudinal coverage, the area is roughly
between 98o E and 122o W, or a total of nearly 40% of the earth's equatorial circumference. This expanded Fishing Area 71 is a nearly complete coverage of 2 natural biogeographic units, the Western Pacific and the Pacific Plate regions, that can be collectively termed the Western Central Pacific (WCP). It has the richest diversity of marine species in the world. It does not cover the Hawaiian Islands and Johnston Island, which are clearly tropical western Pacific in their biogeographical affinities. These excluded islands exhibit a high degree of endemism that would substantially increase the species coverage of this guide. In addition, there are already a number of excellent guides that cover the marine flora and fauna of the Hawaiian Islands.
Fig. 1 Area covered by this guide (shaded): FAO Fishing Area 71 plus the South Pacific Commission Area (enclosed by dotted lines)
The Living Marine Resources of the Western Central Pacific
Fig. 2 The countries of the Western Central Pacific
Fig. 3
The major seas, gulfs, and island groups of the Western Central Pacific
4 Oceanography Winds and Currents Two major wind patterns largely influence the currents of the WCP: trade winds and monsoons. Trade winds dominate in the Central Pacific (Fig. 4a) while monsoon patterns dominate the western Pacific. Trade winds are caused by warm air rising above hot equatorial regions which is deflected by the rotation of the earth from west to east. Consequently, air is drawn toward the equator where it is hottest and deflected toward the west because of the earth's rotation. Therefore, trade winds flow from the northeast in the tropical northern hemisphere and from the southeast in the tropi-
The Living Marine Resources of the Western Central Pacific cal southern hemisphere. These in turn push water from east to west (Fig. 4b) in 2 huge gyres north and south of the equator. These primary currents are called the North and South Equatorial Currents. They cause water to build up in the western part of the Pacific. To redress this, the Equatorial Countercurrent flows eastward inbetween the North and South Equatorial Currents along the equator. As the North Equatorial Current encounters the Philippines, it flows partly into the Celebes Sea, but mostly flows northward and becomes a major warm current, the Kuroshio. In the West, the South Equatorial Current mostly flows southward along the coast of Australia to become the Eastern Australia Current, but it also partially flows into the seas north of Australia.
Fig. 4a Major wind patterns in July (meters/second)
Fig. 4b Ocean currents in July (knots)
Introduction In the western Pacific, monsoon winds influence the flow of water around Southeast Asia and northern Australia. From around May to October the Southwest Monsoon is a result of cool ocean air flowing toward the warm Asian continent (Fig. 4a). At this time, air flows in a northeasterly direction over Southeast Asia and in a northwesterly direction over the Australian continent. This pushes water mostly in a westerly direction in the Arafura, Timor, Banda, and Java seas and mostly in a northeasterly direction in the South China Sea (Fig. 4b). From around November to April
5 the Northeast Monsoon prevails, which is a result of cool continental air flowing toward the relatively warmer Indian Ocean (Fig. 5a). This causes winds to predominately blow toward the south and southwest, around Southeast Asia and northern Australia. The currents subsequently flow in the opposite direction from those of the Southwest Monsoon (Fig. 5b). In the South China Sea flow is predominantly southwest, and in the Java, Banda, Timor, and Arafura seas flow is mostly east.
Fig. 5a Major wind patterns in January (meters/second)
Fig. 5b Major ocean currents in January (knots)
6 Patterns of Productivity The great open expanse of the tropical Pacific Ocean is, for the most part, a vast desert in terms of productivity. Its primary production, on the average, is among the lowest of all habitats. Tropical and subtropical open ocean primary productivity is typically around 40 g of Carbon per square meter per year (gC/m2/yr) which is around 1/3 the primary productivity of open ocean temperate regions. This is because the constant warm conditions in the tropics keep a consistent thermal stratification in the upper layer of the ocean throughout the year preventing mixing with lower, cooler, nutrient-rich water. However, in upwelling areas and coastal areas, including waters near Oceanic islands, nutrients in upper sunlit layers of the ocean are more plentiful and yearly primary productivity is much
The Living Marine Resources of the Western Central Pacific higher (Fig. 6). Along the equator in the Central Pacific is an area of upwelling of nutrient-rich deeper water caused by the diverging flow of the North Equatorial Current and the Equatorial Countercurrent. This area has higher primary productivity than most of the surrounding open ocean. The area around and between northern Australia and Southeast Asia also has a significant inflow of nutrients from terrestrial runoff, and rich, shallow sediments from which nutrients can be drawn. Consequently, the primary production around these areas is high. The secondary productivity from zooplankton in the Western Central Pacific (Fig. 7) roughly mirrors the pattern of primary productivity. Highest zooplankton production is found in the SouthEast Asian, coastal, and Central Pacific upwelling areas.
Fig. 6 Primary productivity from phytoplankton (gC/m2/yr) (after FAO, 1981) Fig. 7 Secondary productivity from zooplankton (mg/m3) (after FAO, 1981)
Introduction The Western Central Pacific hosts the most extensive tropical continental shelf area (depths shallower than 200 m) of the world (Fig. 8). Continental shelf regions typically support the most highly productive communities. The standing crop of the benthos (Fig. 9) reflects the depth and patterns of phytoplankton and zooplankton production. Nearshore shallow areas typically have greater nutrient availability and support high benthic primary and secondary production. Deeper areas rely on primary production occurring in the upper layers of the ocean. This rain of food from above passes through a number of trophic levels. The deep Ocean Floor areas are also limited by physical factors such as low temperatures and high pressure. Consequently, annual secondary production is generally lower than in coastal areas.
7 In contrast to the depauperate open ocean, coastal habitats in the tropics attain very high primary production. The Coral Reefs, seaweed beds, estuaries, and mangrove swamps that dominate the shorelines of the WCP typically attain primary productivity values of between 800 and 1 000 gC/m2/yr. This is around 20 to 25 times more productive than the tropical open ocean. These habitats are able to attain high productivity, even in oceanic islands surrounded by nutrient poor water by efficiently fixing and recycling nutrients locally within their ecosystems. In addition to high production, these critical coastal habitats are host to an extremely high diversity of marine organisms. The extensive continental shelf area around Southeast Asia is also very productive, attaining primary productivity values over 200 gC/m2/yr. This supports the soft-sediment benthic offshore habitats of the region.
Fig. 8 Depth patterns Fig. 9 Benthic standing crop (g/m2) (after Couper, 1990)
8 Geology Four major lithospheric plates dominate the geology of the western and central Pacific (Fig. 10). These include the Pacific, Philippine, Indian-Australian, and Eurasian plates. The Pacific Plate, currently the largest of the earth's lithospheric plates, commenced formation about 190 million years ago (Uyeda, 1977). After the breakup of Gondwanaland this plate greatly expanded westward. It currently moves in a west-northwest direction, although 43 million years ago it moved in a northwest direction. The Pacific Plate collides with and subducts the other 3 plates along its western edge. This area of subduction produces the volcanism that created the characteristic island archipelagoes of the western margin of the Pacific Plate. Subduction also results in a rim of deep trenches along the western margin (Fig. 8). The oldest rocks on the Pacific Plate are along its western edge and are from the upper Jurassic and lower Cretaceous (older rocks existed but have been subducted). The islands on the plate formed by magma welling up from the mantle through fault lines and from mantle "hot spots" onto the ocean floor. Subduction, cooling of the plate from east to west, and convection currents in the mantle all possibly contribute to the deepening of the seafloor toward the western rim. This, and the west-northwesterly movement of the plate cuases islands to sink at the northwestern points of many island chains. The Philippine Plate originated more than 50 million years ago (Hall, 1996) and is presently moving westward. The western edge of the Philippine Plate is subsiding and is an area of deep trenches, vulcanism, and island chain formation on the adjacent Eurasian Plate resulting in many of the Philippine Islands. The Pacific and Philippine plates bear only islands while the Indian-Australian and Eurasian
The Living Marine Resources of the Western Central Pacific Plates bear large continental crusts and associated continental shelves. Relative to 65 million years ago (Fig. 11), the Australian continent has moved a considerable distance northward toward the Eurasian continent. During this time, the Australian continent has traversed the Indian Ocean bringing the Australian-New Guinean land masses close to Southeast Asia. As early as the Jurassic, continental blocks rifted from northern Australia (AudleyCharles, 1988). These blocks collided with, and now contribute to the Laurasian continental crust, including parts of Southeast Asia from southern Tibet to Malaya, parts of Borneo, Sumatra, and islands of West Sulawesi and Banda. Other interpretations of the geological events in this region exist (e.g., Metcalfe, 1988). However, it appears that at least one wave of Gondwana-origin continental crust migrated north and collided with Laurasia in the Southeast Asian region prior to the approach of Australia-New Guinea. The IndianAustralian Plate is subsiding under the Eurasian Plate and along this border trenches, volcanism, and island formation are also contributing to the Indonesian Archipelago. The region between Australia and the Eurasian continent encompasses extensive continental shelves, including the Sunda Shelf on the Eurasian Plate, and the Arafura Shelf on the Indian-Australian Plate. Biogeography: Distribution and Diversity The Indo-Pacific Region Historically, the science of biogeography has gone through a descriptive phase, and a more recent phase centred around a debate on the relative contribution of dispersal versus vicariance. The descriptive phase involved the delineation of areas, called realms, regions, or provinces. Each of these biogeographic areas contains an assemblage of organisms that is distinct, to varying degrees, from assemblages in other areas. Often within each of
Fig. 10 Major lithospheric plates of the world
Introduction the larger biogeographic units are identified subareas of distinct endemism, or areas in which a number of species distributions are restricted. For largely historical reasons, but also because of geology and ecology, the biogeography of the terrestrial and marine regions of the Pacific Ocean were circumscribed differently (Kay, 1980). The area covered by this guide, the Western Central Pacific, is part of a larger marine biogeographical area called the Indo-Pacific. This larger area includes mostly the tropical and subtropical regions of the Indian Ocean (including the Red Sea and the Persian Gulf) eastward to the central Pacific Ocean through Polynesia to Easter Island. Ekman (1953) distinguished between eastern Pacific and western Pacific faunas and hypothesized the vast ocean expanse between Polynesia and the Americas as the East Pacific Barrier separating the 2 provinces. He named the area we call the Indo-Pacific as the Indo-West Pacific. Current usage (e.g., Myers, 1989) often restricts the term West Pacific to the waters around Southeast Asia eastward to Samoa. The term Central Pacific or Pacific Plate is often used for the central oceanic islands of the Pacific. Springer (1982) presented convincing evidence to recognize the Pacific Plate as a major subregion of the IndoPacific. We use the term Western Central Pacific as a practical shorthand to describe the area covered here, that is, the tropical and subtropical West Pacific and Central Pacific (Pacific Plate), minus the Hawaiian Islands. Vicariance and Dispersal Much of the discussion in the last 20 years in biogeography has centred around the relative contributions of vicariance or dispersal as causal mechanisms in determining the distributions of organisms. Both are powerful forces in shaping species distributions. Vicariant events in the marine
9 realm include mostly geotectonic events and the restriction in distributions due to climate and current change. Vicariant events provide a means of dispersion over geologic time through the movement of lithospheric plates. Geotectonic processes also give rise to changes in topographical relief and hence are an important factor in joining and isolating populations geographically. Isolation can result in allopatric speciation, considered the most prevalent speciation mechanism. Therefore, vicariant events are prime factors influencing large-scale, long-term distribution patterns. An example of this can be seen in the distribution of fossils and higher taxonomic categories of many marine groups. Many fossils and current higher-level taxa show a common, tropical cosmopolitan distribution consistent with the existence of the ancient Tethys Sea. This sea began as a large gulf between Laurasia (the ancient continental landmass composed of present day North America and Eurasia) and eastern Gondwana (the ancient continental landmass originally composed of all the present day southern continents plus the Indian subcontinent) prior to the breakup of Pangea more than 180 million years ago. During the Jurassic, which ended around 135 million years ago, northern Laurasia separated from southern Gondwana. At this time, the Atlantic Ocean was formed, and the Tethys Sea became continuous from the Indo-Pacific through to the Caribbean.The marine fauna that existed at this time in the Tethyan Sea was therefore a continuous Indo-Pacific-Caribbean fauna. Around 65 million years ago northeastern Gondwana reunited with Eurasia separating the Indo-Pacific from the Mediterranean and Atlantic. This vicariant event imposed allopatry and subsequent divergence of Atlantic and Indo-Pacific faunas. Vicariant events also can influence speciation and hence distributions on a smaller scale. Rosen (1984) developed a model that demonstrates the potential influence of vicariance in island chains.
Fig. 11 Position of continents 65 million years ago
10 Continuous populations on islands close enough for dispersal to predominate can become separated through the formation of barriers. These barriers can be in the form of islands drifting apart or changes in currents such that migration or dispersal between islands is interrupted. This results in allopatry and potential speciation. Hall (1996) shows how a number of the major islands of Southeast Asia have changed position relative to one another considerably in the past 50 million years. Current patterns also presumably changed substantially during the formation of the Indo-MalayPhilippine archipelago. Climate and sea level change have also been powerful vicariant factors in the western Pacific. McManus (1985) suggested that the lowering of sea level during the Pleistocene would have resulted in a number of effectively isolated marine basins in Southeast Asian seas. Fleminger (1986) showed how a combination of sea level lowering of 100 to 200 m and increased upwelling during the glacial periods of the Pleistocene could have served as a barrier between the western Pacific and Indian oceans. Springer and Williams (1990) further suggest that the lowered temperatures and sea level during the ice ages could have caused many species to become locally extinct in Southeast Asian seas. Current disjunct Indian and Pacific ocean distributions of certain species may have had continuous distributions prior to glacial periods. These species then failed to become reestablished in Southeast Asian seas after glacial periods. Dispersal in the ocean by migration or current transport can create deviations from distribution patterns originally dictated by vicariant events. These deviations can accumulate with time and become an important factor in modifying vicariant-determined distributions. An example from the western and central Pacific is the presumed conduit of western Pacific
The Living Marine Resources of the Western Central Pacific species onto the Pacific Plate (Springer, 1982; Myers, 1989). A tectonic process underlies the formation of a distinct Pacific Plate biota (Springer, 1982) while dispersal through "island hopping" brings western Pacific species onto the plate. Potential conduits predominate from west to east as the island chains of Micronesia, Melanesia, and Polynesia. Indo-Malay-Philippine Diversity Vicariance and dispersal have resulted in distinct diversity patterns in the tropical western and central Pacific. The 2 most salient patterns are the high diversity centred on the Indo-Malay-Philippine archipelago and the decrease in diversity from west to east (Fig. 12). Springer (1982) argues that there is a distinct biota associated with the formation of the Pacific Plate, and the abrupt decrease in west to east diversity at the Pacific plate margin is due to an hypothesized ancient barrier at the margin. There is a gradual decline south to southeast onto the Pacific Plate. Higher diversity on the western side of the Pacific Plate is presumably because of encroachment of Philippine Plate, Indian-Australian Plate, and Eurasian Plate species onto the Pacific Plate. The marine tropical shore fauna diversity centred in Southeast Asia is greater than any on earth. Early attempts to explain this invoked a "centre-oforigin" theory, stating that species-rich areas are sources of new species from which species migrate out to regions of lower diversity. However, evidence for sympatric speciation is scarce and until this theory is recast in a model incorporating allopatric speciation and geological evidence, it will suffer from theoretical weakness. There have been other attempts to explain the high diversity of the Southeast Asian area (e.g., Rosen, 1984; McManus, 1985; Fleminger, 1986; Myers, 1989; Mukai, 1993) and it is likely that a number of explanations will need to be synthesized before a single view is
Fig. 12
Numbers of families of shorefishes around the Western Central Pacific (after Springer, 1982)
Introduction accepted (Potts, 1985). Presented below are a number of different factors that may contribute to this high diversity. I argue that the high marine diversity can be explained by a combination of the diversity of lithospheric plates bordering the region, the direction of movement of the plates, the sea level lowering events of glacial periods, and that all these factors occur in a tropical area with the largest concentration of equatorial shelf habitat on earth. Lithospheric plate diversity leads to taxonomic diversity: Southeast Asia is mostly on the Eurasian plate but the area is bordered in close proximity by the Indian-Australian, Pacific, and Philippine plates (Fig. 10). This represents perhaps the greatest concentration of plates in a continuous marine area. If we accept that separate plates spawn separate marine biotas, as is implicit in Springer's (1982) treatise, then simple spillage (dispersal) of different species into Southeast Asian seas from the surrounding plates could serve as a substantial source of diversity. In addition, the concentration of lithospheric plate interfaces in the area also spawns a high number of geotectonic events from interaction between the plates. For example, Hall's (1996) geological reconstruction of Southeast Asia hypothesizes that the major components of the present day Philippine Islands came from at least 4 widely separated origins. These and other associated vicariant events presumably affected both species assemblages and continuity of individual species distributions; the latter potentially leading to subsequent population divergence and speciation. Springer (1982) notes that taxonomic diversity is to a large degree dependent on the number of vicariant events and that more of these events probably occurred in the Southeast Asian area than elsewhere in the Indo-Pacific. While dispersal from adjacent lithospheric plates and tectonic activity may contribute to diversity, other factors may also contribute to the high diversity of Southeast Asian seas. The tectonic conveyor belt - all roads lead to Southeast Asia: The 3 plates bordering the Southeast Asian leg of the Eurasian Plate are all moving relatively toward Southeast Asia. Subduction zones rim the area on all marine borders. The movement of the plates toward Southeast Asia would tend to "dump" new species into the region like giant conveyor belts after the species have formed on their respective plates (the idea of moving plates acting as conveyor belts or "Noah's Arks" has been used to explain mammalian distributions by McKenna (1973), but has not, to my knowledge been used as an explanation for the high diversity found in Southeast Asian seas). This assumes, at minimum, ability to disperse across the areas of subduction bordering the area. Springer (1982) assumes this ability in recognizing an extended Pacific Plate distribution onto the Philippine Plate for a number of taxa. The pouring of taxa onto the southern leg of the Eurasian Plate could substantially increase diversity in the region particularly at higher taxonomic levels since the geologic time asso-
11 ciated with transport by the tectonic conveyor should be counted in millions or tens of millions of years. This is illustrated by considering the path of Australia in the past 65 million years (Fig. 11). At the time of the Cretaceous-Tertiary boundary, Australia was still connected to Antarctica far to the south relative to its present location. The 65 million years it spent traveling toward Southeast Asia was a period when the families and genera of many of the dominant nearshore marine taxa such as perciform fishes evolved (Patterson, 1993). If any of these originated on the Australian Plate during this time, they could have contributed to the diversity of Southeast Asian seas via dumping from the tectonic conveyor. Furthermore, if we accept that separate blocks of gondwanan continental crust arrived in the region prior to the arrival of Australia, then 2 or more shipments of potentially differentiated nearshore faunas dumped into the region from the Indo-Australian Plate. The high diversity of shorefish families in Southeast Asia (Fig. 12) supports the notion and geological time frame of the tectonic conveyor idea but further evidence based on phylogenetic relationships is required to test this hypothesis. Sea level lowering and current upwelling: the key Indian-Pacific Ocean barrier and isolated basins: As mentioned above, Flemminger (1986) demonstrated that sea level lowering and current upwelling could have sustained an effective barrier between the Indian and Pacific oceans during Pleistocene glacial periods. This would have separated populations and provided an allopatric mechanism for speciation of the numerous marine forms in the area. After the glacial periods these differentiated sister species could have remixed in the area increasing diversity over previous levels, assuming that some of these sister species were capable of co-existence. Sea-level lowering in Southeast Asia during the Pleistocene may also have resulted in many isolated seas and bays contributing further to diversity in the region (McManus, 1985). This may have resulted in small isolated populations that could rapidly speciate. Evidence for this is shown by the many Philippine shorefish species that appear to be localized on 1 or 2 islands (Springer, personal communication). The greatest concentration of amenable tropical shallow-water marine habitats: Appropriate ecological conditions must be present to support high diversity. Ekman (1953) pointed out the existence of a broad shelf area in the tropical zone between Australia and Asia. Indeed, if one were to circumscribe a 15° band on either side of the equator on a map showing the shelf area in relation to land and deep-water areas of the earth, Southeast Asia and northern Australia stand out as having, by far, the largest tropical shelf area on earth. This vast shelf area and the most extensive archipelago in the world, the Indo-Malay-Philippine
12 archipelago, engenders a wealth of habitats. This includes the most extensive area coverage of coral reef, mangrove, seaweed bed, and tropical estuarine habitat of the world. These shelf and nearshore habitats are the most productive marine habitats. The combination of immense habitat diversity and extent, and high primary and secondary production in Southeast Asian seas (Figs 6, 7, 9) presumably nurtures the existence of high taxonomic diversity by reducing the likelihood of competitive exclusion on a grand scale. Greater resource availability may also support larger populations and reduce the probability of extinction. The extent of shallow-water habitat in Southeast Asian seas may also influence diversity through an area effect. There is a well-known positive relationship between size of geographic area and the number of species it contains. This presumably influences rates of extinction and speciation. Extinction rates may be lower in areas large enough to harbour large populations. Large areas provide more refuges from localized geological or climatological effects. Large areas may also tend to have a greater number of geological events that could isolate one population from another within the area, promoting speciation. A complex geology, geography, climatological history, and ecological capacity apparently favours a decidedly positive balance between extinction and speciation in Southeast Asian Seas. Fisheries Diversity is the keyword in describing the living marine resources of the Western Central Pacific. The extreme numbers of species found and fished in this region is unmatched anywhere on earth. The variety of fishing methods and different modes of utilization is also exceptional. Add to this a vast geographic coverage and a dizzying cultural and economic array, and a description of the fisheries in the WCP becomes difficult, indeed. Some of the important features of the fisheries in the WCP are outlined here. For the purpose of a fisheries review, the WCP area can be delineated into 3 major geopolitical entities: Southeast Asia, the South Pacific Islands, and Australia. Each of these areas has its own distinct geophysical features, biological makeup, cultural identity (although often highly diverse within a region), economic characteristics, and dominant fisheries. Southeast Asia is characterized by extensive continental shelf area, very high biological productivity, the highest diversity of marine species of anywhere on earth, dense human population particularly in coastal areas, and fisheries dominated by trawling but also supporting a wide diversity of other fishing methods. The South Pacific Islands are characterized by narrow continental shelf and extensive oceanic waters, concentrations of biological productivity and diversity mostly on coral reefs, generally low population
The Living Marine Resources of the Western Central Pacific pressure, and foreign industrial tuna and smallscale coastal fisheries. The part of Australia in the WCP is characterized by a large continental shelf in the north and the largest barrier reef in the world, but relatively low fisheries production compared to the size of the Exclusive Economic Zone (EEZ). Australia also has relatively low population pressure and a western culture that engenders an extensive recreational fisheries rivaling commercial fisheries in their total economic impact on the country. Reviews of fisheries resources has been done for Southeast Asia by Morgan and Valencia (1983) and Martosubrotu (1997), for the South Pacific Islands by Wright and Hill (1993), Dalzell et al. (1996), and Majkowski (1997), and for Australia by Kailola et al. (1993). Across these 3 regions are few unifying features in their fisheries. They share many of the same species and similar fishing practices. However, the only really unifying feature of fisheries across the WCP is that very few fisheries are dominated by a single species. Multispecies catches, often in the extreme, characterize the area. The fisheries production of the WCP is dominated by the landings from Southeast Asian countries (Table 1). Indonesia, Thailand, and the Philippines account for nearly 6.7 million Metric tons of landings in 1995 according to the FAO Yearbook Statistics. This represents almost 80% of the landings of those countries bordering the WCP area. These 3 countries account for an estimate of around only 16% of the total Exclusive Economic Zone (EEZ) but about 75% of the population in the WCP. However, it is difficult to estimate EEZ, population, and other country statistics exclusively for the WCP area because a number of the WCP countries border other FAO fishing areas. Aside from FAO fisheries statistics, other statistics are not available for those portions of the country that only border FAO Fishing Area 71. Australia also borders FAO Fishing Areas 81 and 57; Indonesia, Malaysia, and Thailand also border FAO Fishing Area 57, and Viet Nam also borders Fishing Area 61 (although the FAO Fisheries statistics does no break down these landings according to the 2 Fishing Areas for Viet Nam). For the purpose of roughly estimating WCP specific country statistics, other statistics were scaled according to the proportion of fisheries landings recorded in FAO Fishing Area 71, for those countries bordering more than one FAO fishing area (Tables 1 and 2). In contrast to the high production versus EEZ area for Southeast Asian countries of the WCP area, Australia and the South Pacific Commission (SPC) countries extract a relatively small proportion of fisheries production (Table 2). Southeast Asian countries record roughly over 1 100 t of landings per square kilometer of EEZ per year from the WCP. Australia records roughly around 23 t/km2 of EEZ while the SPC countries record around 5 t/km2 of EEZ. The latter is an underestimate of total fisheries landings from the area since a number of
Land Area (`000 km2)
Coastline Length (km)
EEZ Area (`000 km2)
1995 Fisheries (mt) (FAO Area***)
American Samoa
59 566
18 260 863* 7 617 930*
25 760*
9 000*
41 633 (71) 58 377 (81) 114 186 (57)
Brunei Darus
299 939
5 270
4 786
10 861 218
176 520
31 231
Cook Islands
19 561
1 830
1 114
East Timor**
Federated States of Micronesia
125 377
6 112
2 780
21 145
782 381
18 270
1 129
1 290
30 828
French Polynesia
224 911
3 660
2 525
5 030
8 818
156 974
206 611600* 1 826 440*
54 716*
5 410*
2 620 560 (71) 676 050 (57)
80 919
1 143
3 550
24 683
19 962 893*
328 550*
4 675*
609 704 (71) 610 594 (57)
Marshall Islands
58 363
2 131
10 273
New Caledonia
187 784
18 575
2 254
1 740
4 000
2 174
Northern Marianas
52 284
1 482
16 952
1 519
1 450
Papua New Guinea
4 394 537
451 710
5 152
3 120
12 500
74 480 848
298 170
36 289
1 786
1 732 890
3 396 924
13 661
Solomon Islands
412 902
27 540
5 313
1 340
46 462
58 851 357*
511 770*
3 219*
2 320 663 (71) 901 437 (57)
1 482
106 466
2 596
10 146
177 504
14 760
2 528
2 600
Viet Nam
73 976 973*
325 360*
3 444*
900 000
Wallis and Futuna
14 659
Western Samoa
214 384
2 850
1 400
Table 1. Major physiographic and economic features in the countries of the Western Central Pacific area. Population, land area, and coastline length are from the 1997 CIA Factbook. EEZ estimates from country reports. Fisheries catch is from the 1995 FAO Yearbook of Fishery Statistics.
*Estimates are for the entire country, not just the portions fronting the Western Central Pacific. **Separate statistics not reported for this country; estimates are mostly included under Indonesia. ***Fishery statistics for FAO areas not covered by this guide are included for countries with catches in areas outside the WCP area to give an idea of relative importance to each country of Fishing Area 71 which is covered in this guide.
The Living Marine Resources of the Western Central Pacific
Country/Region Population*
EEZ Area * (`000 km2)
1995 Fisheries (mt) (Area 71+SPC Area)
Australia Southeast Asia SPC Total
3 469 564* 379 626 546* 7 109 655
1 746* 7 234* 29 325
41 633 8 233 495 159 782 8 434 910
Table 2. Estimated population, Exclusive Economic Zone (EEZ), and fisheries catch for regions of Fishing Area 71 and the South Pacific Commission (SPC)
* Individual estimates for these numbers specifically for Fishing Area 71 are not readily available. For countries that front fishing areas other than Area 71 and the SPC area, these numbers were adjusted based on the proportion of total catch contributed by Fishing Area 71. This is not an accurate estimator for these numbers but gives a rough indication of relative importance of Fishing Area 71.
non-WCP countries operate long distance fleets in the WCP (Table 3). Much of these landings are tuna longline, purse seine, and pole-and-line fisheries that operate in the SPC (Wright and Hill,1993; Dalzell et al., 1996; and Majkowski, 1997). In addition, a large proportion of the landings in the SPC countries is subsistence level (Majkowski, 1997) that may go unrecorded or underestimated in FAO statistics. The landings from Australian waters is low presumably because of the limited shelf area and low nutrients of Australian waters (Kailola et al., 1993). In contrast, Southeast Asian fishing grounds offer a wealth of highly productive waters with extensive trawlable shelf area. The fisheries production of the countries in the WCP has shown a steady increase in the last 20 years (Fig. 13). This increase is driven largely by the rapid development of trawl fisheries in Fishing Area 71 (Martosubrotu, 1997) and has continued unabated in the Southeast Asian countries of the WCP area (Fig. 13). Despite this continued increase, there are strong indications of overfishing although the level of knowledge of state of the resources in this area is insufficient (Martosubrotu, 1997). The fisheries production in the SPC countries and Australia has shown a modest increase in the last 20 years (Fig. 14). However, this production has leveled off, particularly in the last 5 years indicating that these resources have reached the limit of exploitation. Catches from industrial local and long distance tuna fleets has also leveled off markedly in the last 5 years in the SPC area (Majkowski, 1997) indicating further that resource limitations have also been reached for tuna fisheries of the WCP. Of the approximately 1 080 taxonomic statistical categories listed in the 1995 FAO Yearbook of Fishery Statistics (FAO, 1997) about 175 have catches recorded in the WCP area. The most important 50 of these WCP statistical units cover a wide taxonomic range from seaweeds to tunas (Table 4). Over half of these statistical units are species aggregations. This landing data is unfortunately of limited use in biological management of fisheries since species-specific population parameters are required for rigorous management.
These statistical aggregations are necessary largely because of the difficulty in identifying taxonomic units to species level. However, with the availability of this WCP Identification Guide, the ability to identify species accurately will become more practical. This will likely cause an increase in the reporting of numbers of taxonomic units in the future from the WCP - not because a greater diversity of species are being exploited but because our ability to identify species will improve. This phenomenon of more numerous species and taxonomic units being recorded in fisheries statistics has been recorded on a wider scale. The number of overall taxonomic units reported in the FAO Fisheries Yearbook has increased markedly over the past 25 years. This is largely due to our improved ability to identify the organisms being fished. This phenomenon is called the "Fischer Effect" after the founder of FAO's Fisheries Department Species Identification and Data Programme, Walter Fischer. His publication series of Identification Sheets, Identification Field Guides, and Species Catalogues have led to an improved ability to identify fisheries resources and hence improve fisheries management capabilities worldwide. The present WCP series intends to contribute to this purpose.
1995 Fisheries Landings (mt)
China Main
8 210
277 592
Korea Republic
213 720
Russian Federation
4 981
Taiwan Province of China 152 415
153 840
Total 810 758
Table 3. Landings from Fishing Area 71 made by countries not bordering Fishing Area 71. These are mostly purse seine, longline, and pole-and-line tuna catches.
Fig. 13 FAO Fisheries Statistics landings in metric tons for all WCP countries recorded from Fishing Area 71 and the South Pacific Commission area and from the Southeast Asian WCP countries from Fishing Area 71 from 1976 to 1995
Fig. 14 FAO Fisheries Statistics landings in metric tons for the South Pacific Commission countries and for Australia from Fishing Area 71 from 1976 to 1995
The Living Marine Resources of the Western Central Pacific
Statistical taxonomic unit (common name) Decapterus spp (scads) Rhodophyceae (red seaweeds) Stolephorus spp. (stolephorus anchovies) Katsuwonus pelamis (Skipjack tuna) Osteichthyes (marine fishes nei) Sardinella spp. (sardinellas) Carangidae (carangids nei) Natantia (natantian decapods nei) Engraulidae (anchovies nei) Thunnus albacares (yellowfin tuna) Leiognathidae (ponyfishes) Euthynnus affinis (kawakawa) Sardinella gibbosa (goldstripe sardinella) Auxis spp. (frigate and bullet tunas) Loligo spp. (common squids) Scombroidei (tuna-like fishes nei) Mytilus smaragdinus (green mussel) Paphia spp (shortneck clams) Peneus spp (peneus shrimps nei) Rastrelliger kanagurta (Indian mackerel) Nemipterus spp (threadfin breams) Sepiidae, Sepiolidae (cuttlefishes) Sardinella lemuru (Bali sardinella) Scomberomorus commersoni (Spanish mack.) Decapterus russelli (Indian scad)
1995 landings (`000 mt) 282 245 203 177 153 152 146 118 104 102 98 97 96 96 94 90 87 83 79 75 73 51 50 49 48
Statistical taxonomic unit (common name) Peneus merguiensis (banana prawn) Thunnus tonggol (longtail tuna) Ariidae (sea catfishes nei) Dussumieria acuta (rainbow sardine) Percoidei (percoids nei) Reptantia (marine crabs nei) Elasmobranchii (sharks, rays, skates, etc.) Sergestidae (sergestid shrimps) Exocoetidae (flyingfishes) Mugilidae (mullets) Tylosurus spp (needlefishes) Selar crumenophthalmus (bigeye scad) Caranx spp (jacks, cravalles nei) Lutjanidae (snappers, jobfishes nei) Caesionidae (fusiliers) Mullidae (surmullets, goatfishes) Rastrelliger brachysoma (short mackerel) Rajiformes (skates and rays, nei) Metapenaeus spp (metapeneus shrimp nei) Sciaenidae (croakers, drums nei) Portunus pelagicus (blue swimming crab) Serranidae (groupers, seabasses nei) Lutjanus spp (snappers nei) Rhopilema spp (jellyfishes) Sphyraena spp (barracudas)
1995 landings (`000 mt) 46 46 41 39 37 37 37 37 36 35 34 33 31 31 30 30 29 28 26 26 25 25 24 20 20
Table 4. The 50 most important taxonomic statistical units listed from the WCP in the FAO Fisheries Yearbook and their 1995 landings
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