Studies of Indonesian Tuna Fisheries [2]

CHANGES IN YELLOWFIN ABUNDANCE IN THE GULF OF TOMINI AND NORTH SULAWESI

C.P. Mathews, D. Monintja, Nurzali Naamin

ABSTRACT

Yellowfin tuna are taken on four Tomini Gulf (North Sulawesi) fishing grounds around "rakit"(small shallow-water fish aggregating devices) targeted towards scads and small yellowfin and around "rumpon" (larger deep-water fish aggregating devices) targeted towards medium-sized yellowfin. In Gorontalo, yellowfin landings increased from 1988 to a peak of more than 1,500 mt in 1990; the landings then declined steadily until 1995. Landings in Tilamuta, Paguat and Marisa fluctuated, but tended to peak between 100 and 200 mt around 1990. The CPUE at Gorontalo peaked in 1990 and fell markedly from 1990 onwards in all four fisheries; in 1995 the CPUE fell to about 30% of 1990 level in Gorontalo and to less than 10% of the 1990 levels at Tilamuta, Paguat, and Marisa. The sharp decline in CPUEs coincided with the extension of intensive offshore fishing by tuna longliners (mostly from Taiwan) and with the introduction of large-scale offshore industrial purse seining (which targets skipjack but also takes substantial amounts of yellowfin) by Philippine boats around North Sulawesi in 1990. The marked decline in yellowfin abundance suggests that offshore fishing impacted the Tomini Gulf fisheries.(fulltext ..>>)

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Environmental Changes on the Coasts of Indonesia [2]

THE CHANGING COASTLINES OF INDONESIA


Eric C. F. Bird and Otto S. R. Ongkosongo

Although there has been geomorphological research on several parts of the Indonesian coastline, the coastal features of Indonesia have not Yet been well documented. The following account-based on studies of maps and charts, air photographs (including satellite photographs), reviews of the published literature, and our own traverses during recent years-is a necessary basis for dealing with environmental changes on the coasts of Indonesia. Coastal features will be described in a counter-clockwise sequence around Sumatra, Java, Kalimantan, Sulawesi, Bali and the eastern islands, and Irian Jaya. Inevitably, the account is more detailed for the coasts of Java and Sumatra, which are better mapped and have been more thoroughly documented than other parts of Indonesia. In the course of description, reference is made to evidence of changes that have taken place, or are still in progress.

Measurements of shoreline advance or retreat have been recorded by various authors, summarized and tabulated by Tjia et al. (1968). Particular attention has been given to changes on deltaic coasts, especially in northern Java (e.g, Hollerwoger 1964), but there is very little information on rates of recession of cliffed coasts. Measurements are generally reported in terms of linear advance or retreat at selected localities, either over stated periods of time or as annual averages, but these can be misleading because of lateral variations along the coast and because of fluctuations in the extent of change from year to year.

Our preference is for areal measurements of land gained or lost or, better still, sequential maps showing the patterns of coastal change over specified periods. We have collected and collated sequential maps of selected sites and brought them up-to-date where possible.

Coastal changes can be measured with reference to the alignments of earlier shoreline features, such as beach ridges or old cliff lines stranded inland behind coastal plains. In Sumatra, beach ridges are found up to 150 kilometres inland. The longest time scale of practical value is the past 6,000 years, the period since the Holocene marine transgression brought the sea up to its present level. Radiocarbon dating can establish the age of shoreline features that developed within this period, and changes during the past few centuries can be traced from historical evidence on maps and nautical charts of various dates.

These have become increasingly reliable over the past century, and can be supplemented by outlines shown on air photographs taken at various times since 1940. Some sectors have shown a consistent advance, and others a consistent retreat; some have alternated. A shoreline sector should only be termed "advancing" if there is evidence of continuing gains by deposition and/or emergence, and "retreating" if erosion and/or submergence are still demonstrably in progress.

Coastal changes may be natural, or they may be due, at least in part, to the direct or indirect effects of Man's activities in the coastal zone and in the hinterland. Direct effects include the building of sea walls, groynes, and breakwaters, the advancement of the shoreline artificially by land reclamation, and the removal of beach material or coral from the coastline. Indirect effects include changes in water and sediment yield from river systems following the clearance of vegetation or a modification of land use within the catchments, or the construction of dams to impound reservoirs that intercept some of the sediment flow. There are many examples of such man-induced changes on the coasts of Indonesia.

Reference will also be made to ecological changes that accompany gains or losses of coastal terrain, and to some associated features that result from man's responses to changes in the coastal environment. (full text)

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Studies of Indonesian Tuna Fisheries [1]

INTERACTIONS BETWEEN COASTAL AND OFFSHORE TUNA FISHERIES
IN MANADO AND BITUNG, NORTH SULAWESI

Nurzali Naamin, C.P. Mathews, D. Monintja


ABSTRACT

Since 1990 an important offshore industrial tuna fishery has been established in northern Indonesian waters. This fishery is theoretically confined to the EEZ, but in practice it occupies large areas of territorial and archipelagic waters. Fishing is carried out by "sets" or groups of boats based on a single purse seiner, supported by carrier and smaller patrol boats. These groups fish around rumpon (FADs) deployed in waters from 200-4,000 m deep, and take substantial catches, most of which is landed directly into General Santos City and other southern Philippine ports. The offshore fishery lands more than 50,00 mt per year from waters around North Sulawesi and northern Irian Jaya. Coastal fishing is carried out for skipjack by two kinds of small pole-and-line vessels ("funai": 5-15 GT; "huhate": 20-30 GT) in North Sulawesi. The coastal fishery landed less than 9,000 mt of skipjack in 1989, the last year before large scale offshore fishing commenced. Data for Manado and Bitung (North Sulawesi) were analysed to determine the effects of the offshore fishery on the skipjack and yellowfin fisheries based in these cities. Skipjack CPUE fell in Manado (from 50-70 mt/boat/year in 1980 to less than 20 mt/boat/year in 1992) and Bitung (from more than 100 mt/boat/year in 1980 to about 60 mt/boat/year in 1990). Effort on skipjack in Bitung rose slowly from approximately 40 boats in 1986 to more than 100 boats in 1991, and then fell to under 35 boats in 1995; the decline was probably due to competition with the industrial fishery. Industrial CPUE fell from 0.69 mt of tuna/GT of effort/year in 1993 to 0.37 mt/GT in 1995. Available data are insufficient for a complete analysis of offshore-onshore tuna fishery interactions. Nevertheless it is likely that industrial, offshore tuna fishing impacted the coastal fisheries in Manado and Bitung by reducing the amount of skipjack and yellowfin available to the coastal fishery.(full text)

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Environmental Changes on the Coasts of Indonesia [1]

THE INDONESIAN COASTAL ENVIRONMENT

Eric C. F. Bird and Otto S. R. Ongkosongo

Indonesia consists of about 13,700 islands, with an intricate coastline whose length has been estimated as just over 60,000 kilometres by Soegiarto (1976). The islands show considerable diversity of coastal features, related partly to contrasts in the geology and geomorphology of the hinterland and the bordering sea floors, and partly to variations in adjacent marine environments. In terms of global tectonics the Indonesian archipelago occupies the collision zone between the Indo-Australian, Pacific, and Eurasian plates. It is a region of continuing instability, marked by frequent earthquakes and volcanic eruptions. Its mountain ranges are areas of Cainozoic uplift, augmented by large volcanic constructions, and its bordering seas are underlain by unstable shelf areas, especially towards the Java Trench, the subduction zone that lies to the south of the Indonesian island-arc.

Indonesian coastlines show the effects of past and present tectonic instability, volcanic eruptions, and changes of sea level. There have been upward and downward movements of the land, often accompanied by tilting or faulting; outpourings of volcanic lava and ash have influenced coastal features both directly and indirectly; and vertical movements of sea level have resulted in complicated sequences of emergence and submergence of island coastlines. Many characteristics of Indonesian coastal landforms are related to their development under tropical -especially humid tropical-conditions, and it will be useful first to consider these features briefly.

Climate

Although much of Indonesia lies within the humid tropical zone, some parts have sub-humid and even semi-arid climates. Climatic characteristics are determined largely by the position of the Intertropical Convergence zone (ITC), a zone of unstable air and heavy rainfall which migrates north and south over Indonesia, crossing the equator in May and November each year, and reaching latitudes of about 15 south in January. Indonesian climatic stations generally show a more pronounced wet season when the Intertropical Zone of Convergence is to the south, when westerly winds prevail; the dry season occurring after it migrates away to the north, and winds move around to the south-east. Generally the southern part of the archipelago has a smaller mean annual rainfall than the rest of the country, partly because of a reduction in the water content of westerly winds as air masses move to the east, and partly because of the influence of drier air brought in from the Australian region by winds from the southeast during the dry season. In additon, afternoon showers caused by local intensive heating are common, and may occur even in the dry season. The pattern of rainfall is influenced by the orographic factor, notably where moist air is forced upwards as it moves eastwards across mountain ranges, particularly in Sumatra, Java, and Irian Jaya. The wettest coastal areas are thus found to the west of the ranges, and the relatively dry areas in the "rain shadows" to the east (Sukanto 1969).

Winds are generally light to moderate, the most vigorous being the south-easterlies in the dry season. The cyclones of northern Australia and the typhoons of the South China Sea do not reach Indonesia, although waves generated by these disturbances are occasionally transmitted into Indonesian coastal waters.

In terms of Koppen's classification, most Indonesian coastal regions are in Category A, with mean temperatures in the coolest month of at least 18°C., but a few sectors have a sufficiently long and dry winter season to be placed in the semi-arid category BS. Truly humid tropical coasts (Af), with a mean rainfall of at least 60 millimetres in the driest month, are extensive around Sumatra and Kalimantan, in southern Java, much of Sulawesi, and the islands to the east. They give place to monsoonal lam) climates, with a short dry season compensated by a large annual rainfall, along the north coast of Java (Jakarta, Semarang, Bangkalan) and in several minor sectors around Sulawesi, including Ujung Pandang; and to somewhat drier savanna (Aw) climates in the rain shadow areas of northeastern Java (Surabaya, Pasuran) and the islands to the east, and around Timor (Dill, Kupang), which is much influenced by dry air masses arriving from Australia. Sectors dry enough to warrant semiarid (BS) classification are limited, but occur on the north coasts of Lombok and Sumba. Much more information from coastal stations is necessary before climatic sectors around the Indonesian archipelago can be delimited accurately.

The interior uplands record substantially higher rainfall than most coastal regions, so that river systems carry a very large runoff from the high hinterlands.

General Geomorphology

Landscapes in humid tropical environments are subject to the intense chemical and associated biological weathering of rock formations that proceeds under perennially warm and wet conditions. This has led to the formation of deep mantles of decomposed rock material, mainly silt and clay, and in places these are up to 30 metres thick. Away from coastal cliff exposures, natural rock outcrops are rare: they are found locally on resistant sandstones, some limestones, and recently formed lava flows.

The natural vegetation cover is tropical rain forest, with a dense canopy and a thick organic litter that protects the ground from the direct erosive effects of heavy rainfall. A subsurface network of roots also binds and stabilizes the upper part of the weathered mantle. This luxuriant vegetation tends to hold the weathered mantle in place, but on steep slopes the rapid runoff that occurs during heavy rain may wash away surface material even where the vegetation is dense, and landslides and mudflows frequently scar the forested hillsides.

Fluvial Sediments

Runoff is thus typically laden with fine-grained sediment, silt and clay produced by weathering, but in steep areas the streams incise their valleys and derive sand, or even gravel, from the less-weathered underlying rock formations. Coarser sediment is also derived from the lava and ash produced by volcanic eruptions. On steep volcanic slopes lahars are formed, when torrential rainfall saturates and mobilizes masses of pyroclastic debris, which flow down into the valleys. Streams also derive sand and gravel when previously constructed volcanic structures are dissected by runoff.

The combination of steep elevated hinterlands of deeply weathered rock, recurrently active volcanoes, and frequent heavy rainfall produces large river systems that carry substantial quantities of sediment down to the coast. Deposition of this material has built extensive deltas and broad coastal plains, especially in Java, Sumatra, Kalimantan, and Irian Jaya. The lithology of outcrops within each catchment determines the nature of the weathered mantles and strongly influences the composition of sediment loads carried downstream by the rivers. As Meijerink (19771 has shown, the sediment volumes per square kilometre per year from catchments dominated by sedimentary formations are much greater than those from volcanic catchments (Table 11. Where sandy material is carried down to the coast it is reworked by waves and deposited as beach formations along shorelines adjacent to river mouths: the most extensive of these are on the south coast of Java. Silts and clays are incorporated in tidal mudflats and coastal swamps, and deposited in lowlyingareas on and around river deltas. (full text)

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Data Source Identification on Indonesian Coastal Cities

DATA SOURCE IDENTIFICATION ON INDONESIAN COASTAL CITIES FOR QUANTITATIVE EVALUATION OF GLOBAL WARMING STUDY

Puthut Samyahardja

Research Institute For Settlements Technology Ministry of Settlement and Regional Infrastructure Jalan Panyaungan Cileunyi Wetan, Bandung, 40393 PO BOX : 812 Bandung, 40008 INDONESIA E-mail : puthut@indo.net.id, kapuskim@bdg.centrin.net.id


ABSTRACT

As an archipelago area, Indonesia has numbers of cities identified as coastal areas. It is the fact that some cities, especially in Java Island, have more developed than cities in other areas. However, since the administration of data base system is similar for the cities, the availability has slight different. The difficulties and processes of data collection are not comparable for each data sources. A special data arrangement is needed for getting the suitable information. Secondary data collection techniques will be presented for the purpose of coastal cities studies in Indonesia.

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Coastal Management in Indonesia

DECENTRALIZED COASTAL ZONE MANAGEMENT IN MALAYSIA AND INDONESIA: A COMPARATIVE PERSPECTIVE

Hendra Yusran Siry

Agency for Marine and Fisheries Research (AMFR) Ministry of
Marine Affairs and Fisheries (MMAF) Jakarta, Indonesia

Transferring decision-making process from central to local government and enhancing the role of local communities in managing coastal zones is an increasing commitment by governments in Southeast Asia. This article analyzes decentralized coastal zone management in two neighboring countries, Malaysia and Indonesia. The Federal system in Malaysia is argued to be able to influence more decentralized coastal zone management and to promote community-based management approaches. Meanwhile, the large diversity of coastal resources and communities combined with a still as yet tested decentralization policy in Indonesia is argued to bring more challenges in implementing the decentralization and community-based approaches in coastal zones.

The lessons learned in this study provide insight in how far decentralized coastal zone management has taken place in Malaysia and Indonesia. The significant differences in the pattern of coastal zone management in these two countries are discussed in detail.

This study recognizes that co-management and community-based approaches can be appropriate in dealing with coastal zone management. This comparative perspective is important to the development of a bigger picture of sustainable coastal zone management processes and cross-regional knowledge-sharing in Southeast Asia.

Keywords coastal, co-management, community-based, decentralization, Indonesia, Malaysia

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Coral Reef Death ..

CORAL REEF DEATH LINKED TO TROPICAL
WILDFIRES IN INDONESIA DURING THE 1997
INDIAN OCEAN DIPOLE

N.J. Abram (1), M.K. Gagan (1), J. Chappell (1),
M.T. McCulloch (1), W.S. Hantoro (2)

The coral reefs of the Mentawai Islands, Indonesia, experienced catastrophic mortality of close to 100% of the coral and the fish during the 1997 Indian Ocean Dipole (IOD) upwelling event. The link between elevated sea surface temperatures (SST) and coral death is now well known, however the unanticipated Mentawai reef mortality coincided with anomalously cool SSTs and a giant red tide. Ocean productivity in the Indonesian region is generally proportional to the strength of upwelling; therefore the severity of the 1997 Mentawai reef death raises the question of whether the magnitude of the IOD upwelling and red tide during 1997 was unprecedented. Here we examine the tolerance of Mentawai corals to IOD upwelling events over the past 6,300 years using coral skeletal growth and palaeothermometry. High-resolution coral Sr/Ca and 18O reconstructions of SST reveal pre-historic IOD cold anomalies of up to 5.8C.

The magnitudes of these events exceed the strong 1997 IOD upwelling by as much as 1.9C, yet we find no evidence of past coral mortality. From these results it seems that the intensity of the 1997 Mentawai red tide was much greater than expected based on the magnitude of IOD upwelling alone. This implies that an additional source of nutrients must have supported the catastrophic red tide and we propose that these nutrients were provided by the 1997 Indonesian wildfires. These fires were the worst in south-east Asian history and were the combined results of land clearing, past forest disturbance and intense drought driven by the 1997 El Niño-Southern Oscillation and Indian Ocean Dipole events. Using mass balance calculations we show that ironfertilisation of the upwelled nutrient-enriched water by atmospheric fallout from the 1997 wildfires was sufficient to produce the extraordinary red tide, ultimately leading to the unprecedented death of the Mentawai reefs. These findings highlight the escalating phenomenon of tropical wildfire as a potential new threat to coastal marine ecosystems.

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(1) Research School of Earth Sciences, The Australian National University, Canberra ACT 0200, Australia, (2) Research and Development Center for Geotechnology, Indonesian Institute of Sciences, Bandung 40135, Indonesia.

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The Return of EL Niño

Will Warm Water Wreak Havoc When Winds Won’t Blow?

Well, it looks like the next El Niño is coming. Right now many scientists are observing warming over the Tropical Pacific, and this has led to predictions of the next El Niño. El Niño is known to scientists as the El Niño-Southern Oscillation, or ENSO, and is a complicated chain of events that begins in the Pacific Ocean and then spreads to affect the weather around the entire world. What is the El-Niño Southern Oscillation, you ask? The El-Niño Southern Oscillation is the result of a cyclic warming and cooling of the surface ocean of the central and eastern Pacific.

In normal, non-El Niño conditions the central and eastern Pacific region of the ocean is normally colder than its equatorial location would suggest. This condition exists because of the influence of trade winds blowing to the west, a cold ocean current flowing up the coast of Chile, and upwelling of cold deep water off the coast of Peru. The trade winds blow toward the west across the tropical Pacific and these winds pile up warm surface water in the west Pacific. The sea-surface temperatures are much colder near South America because of an upwelling of cold water from deeper levels. This cold water is extremely nutrient rich, leading to high levels of primary productivity, a rich ecosystem, and major fisheries off the coast of Peru.

During an El Niño event, the trade winds weaken in the central and western Pacific for unknown reasons. This weakening causes western Pacific waters to cool, and a warming in the eastern Pacific. The warm, still surface waters in the east Pacific reduce the efficiency of the cold nutrient-rich upwelling, which results in an even larger increase in sea surface temperatures and a dramatic decline in productivity that severely impacts marine life and commercial fisheries in this area. The warming waters in the east Pacific cause huge thunderstorms and floods in the Peru area, while the cooler water temperatures in the west Pacific cause problems such as droughts in Indonesia and Australia.

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