Seram Sea Research Articles

Spatial and Temporal Analysis of Oceanographic Parameters and Their Relationship with Upwelling Phenomena in Seram Sea and Buru Island Waters

Spatial and Temporal Analysis of Oceanographic Parameters and Their Relationship with Upwelling Phenomena in Seram Sea and Buru Island Waters

DINAMIKA POPULASI IKAN CAKALANG (KATSUWONUS PELAMIS) DI LAUT SERAM

This study examines the skipjack tuna fishing industry in North Seram District, Central Maluku Regency, which has been operated by local fishermen for many years. This fishery is categorized as a small-scale and concentrated effort in the Seram Sea, one of the small seas in the Indonesian archipelago, which is part of the Pacific Ocean, covering an area of approximately 12,000 square kilometers. The study employs the length-weight relationship analysis method and the von Bertalanffy growth model. The results indicate that the growth of skipjack tuna can be represented by the equation W = 0.0133L^3.0999 with a determination coefficient of 94%. The b coefficient value for the sampled skipjack tuna was 3.0999, indicating isometric growth (length and weight grow proportionally). The growth coefficient (K) of skipjack tuna was 0.17 per year, with an asymptotic length of 49.586 cm and a t0 value of -0.0748 years. The resulting von Bertalanffy equation is Lt = 49.58{1- e^-0.175(t+0.0748)}, which describes the growth pattern of skipjack tuna in the Seram Sea.

Length-weight relationship, condition factor, and reproductive aspects of Lutke's halfbeak Hemiramphus lutkei (Valenciennes, 1847) from Seram Sea, Maluku, Indonesia

Abstract. Talakua M, Suadi, Djumanto, Setyobudi E. 2023. Length-weight relationship, condition factor, and reproductive aspects of Lutke's halfbeak Hemiramphus lutkei (Valenciennes, 1847) from Seram Sea, Maluku, Indonesia. Biodiversitas 24: 6574-6583. Lutke's halfbeak is one of the Seram Sea's most commercially important fish species, providing food resources and community livelihood for an extended duration. Data and information on fish biology are important for responsible fisheries management. This research aimed to determine Luke's halfbeak's length-weight relationship, condition factor, and reproductive aspects at Seram Sea, Maluku. Fish samples were collected monthly for seven months, from August 2021 to February 2022. Each sample was measured for its length and weight and then dissected for sex and gonad maturity stage determination. The data was analyzed to determine the length-weight relationship, the condition factor, the distribution of gonadal maturity stage, and fecundity. Hemiramphus lutkei (Valenciennes, 1847), originating from the Seram Sea, indicates a negative allometric growth pattern. The average relative condition factor (Kn) of H. lutkei in the Maluku Seram Sea was around 1 and did not show a significant difference between males and females. The condition factor varied during the observation period, ranging from 0.92 to 1.09. The fish are mostly (80%) in good or very good condition. H. lutkei has a high potential fecundity; spawning was predicted throughout the year, with individual fecundity ranging from 263 to 1893 eggs. Luke's halfbeak populations in the Seram Sea could be exploited sustainably; however, this should be conducted with proper management.

Factors Causing Destructive Fishing in the Waters of the West Seram Sea

The use of fishing gear that is not environmentally friendly, which has led to the emergence of destructive fishing activities, is still carried out by fishing communities around the waters of West Seram. The aim of this research is to examine and analyze policies for dealing with the use of non-environmentally friendly fishing gear in the fisheries sector in West Seram Waters. The research method in this research is normative legal research equipped with a socio-legal approach. The approach used in this research is a statutory approach and a conceptual approach. The data collection technique is a literature study and is complemented by field data obtained through observation and in-depth interviews with stakeholders. Next, the data was analyzed qualitatively. The research results show that the fishing communities in Hatusua Village, Kamal Village and Waisarisa Village, which are located around the West Seram Waters, often use fishing gear that is not environmentally friendly when catching fish. The factors that cause them to carry out destructive fishing are factors such as a fairly long span of control making supervision difficult, economic needs; very simple fishing gear; providing assistance is not on target; Pokmaswas are less empowered; and lack of supervision between institutions. Meanwhile, countermeasures to overcome destructive fishing can be carried out through penal and non-penal approaches.

Abundance, characteristics, and distribution of microplastics in Banda Sea and Seram Sea, Indonesia

This study recorded the abundance, characteristics, and distribution of microplastics (MPs) in the surface water in the Banda Sea and Seram Sea. The Banda Sea has known for its complex bathymetry with the shape of a basin in the west and a Sahul Shelf in the east. Due to its unique topography, it controls the water mass exchange in Indonesian waters. The Banda Sea and Seram Sea are dominated by the deep sea with bathymetry of more than 1000 m. Station observation consists of 5 stations in the Banda Sea and 3 stations in the Seram Sea. The microplastic abundance in the surface waters from the Banda Sea and Seram Sea ranged from 4.69 to 22.48 items/L with an average abundance of 14.07 items/L. The highest abundance of MPs was found in Station 1 of Banda Sea due to the closest to Ambon as the capital of Maluku Province. The dominant shape of MPs found such as fibre, fragment, and pellet. The polymer type of MPs found were PET, HDPE, LDPE, PVC, PP, and Nylon. Generally, the abundance of MPs on the surface of the deep-sea area was found lesser than in the coastal area since the MPs distributions are influenced by hydrodynamics and anthropogenic activity.

Analisis Potensi Likuifaksi Menggunakan Data CPT (Cone Penetration Test) di Teluk Bintuni Papua Barat

West Papua is an eastern part of Indonesia that has great potential for earthquakes. Eastern Indonesia's seismic activity was triggered by geographical conditions in three major earthquake paths, namely the zone of the confluence of the Pacific and Papua New Guinea plates, the Sorong fault line and the Tarera – Aiduna fault (Naryanto, 2019). Bintuni Bay is one of the regencies in West Papua Province, located between the south coast of Bird's Head and the coast of the Onin Peninsula, facing the Seram Sea off the west coast of Papua. The sorong fault is one of the active faults (faults) of the earthquake source in the Bintuni Bay area (Ciptakarya.pu, 2002). Liquefaction is one of the failures in the soil structure that can occur due to cyclic loads or earthquake vibrations. Liquefaction is the event of the transformation of noncohesive soil material from solid to liquid properties due to an increase in pore water pressure in the soil cavity. The liquefaction potential was analyzed using the boulanger Idriss method (2014). This method compares the value of CSR (Cyclic Stress Ratio) with CRR (Cyclic Resistance Ratio). The factor of safety value (FS) is used as a limit for potential liquefaction or not. If FS > 1 indicates that the soil layer has no potential for liquefaction, whereas if FS < 1 indicates a potential soil layer of liquefaction. The results of the analysis showed that the magnitude of ≥ 5,6 Mw with soil acceleration (amax) ≥ 0,16 g has the potential to reduce liquefaction with very low to very high categories. Coastal areas have a higher liquefaction potential than land areas.

Record of Hemiramphus lutkei Valenciennes, 1847 from Seram Sea, Maluku, Indonesia with its molecular characterization

Abstract. Talakua M, Suadi, Djumanto, Setyobudi E. 2022. Record of Hemiramphus lutkei Valenciennes, 1847 from Seram Sea, Maluku, Indonesia with its molecular characterization. Biodiversitas 23: 1560-1566. Hemiramphus sp. is a fish species widely distributed throughout the world. However, the area distribution of each species differs between regions. Hemiramphus archipelagicus could be found in Seram Sea, Maluku and Ekas Bay, Lombok, Hemiramphus sp. from North Maluku Sea, and H. brasiliensis from the North Minahasa Sulawesi. The identification of Hemiramphus in Indonesia uses mainly the morphological approach. This study aims to determine the morphometric and meristic character and identify the halfbeak collected from the Seram Sea, Maluku, using a molecular approach. A total of 214 fish samples were used to determine the morphometric and meristic characters of halfbeak, following the measurement method that has been developed previously. All samples of halfbeak showed similar morphological characteristics. Identification by direct sequencing of the cytochrome c oxidase subunit I (COI) gene was conducted from selected samples. The halfbeak caught in the Seram Sea had an elongated flat body shape, the dorsal part of the body is blue-green, the tip of the lower beak is sharp, enlarged towards the base in the oral cavity; the lower beak is reddish-orange and longer than the upper beak. The fin formula of halfbeak from the Seram Sea is D.13-15, P.9-12, V.5-6, A.9-12, C.7/8, and the number of scales at the lateral line is 52-58. Based on molecular identification, the halfbeak species from the Seram Sea was confirmed as Hemiramphus lutkei with a genetic distance of 0.0055 compared to H. lutkei from India, and a genetic distance of 0.0540 with H. balao.

Part I: Hydrological properties within the eastern Indonesian throughflow region during the INDOMIX experiment

The Indonesian Mixing (INDOMIX) cruise of July 2010, resolves the Pacific Ocean water masses spreading from the Halmahera Sea through the Seram Sea, Manipa Strait, Banda Sea, to the Ombai Strait, and along the southern margin of Lesser Sunda Arc across the northern Savu Sea, Sumba Strait, and south of Lombok Strait. This paper focuses on the characteristics and stratification of the water masses, along this path and Part II of this study discusses the biogeochemical aspects. Two companion papers on quantification of turbulent mixing have been published elsewhere. We find: a) A marked transformation of South Pacific (SP) thermocline water within a sharp salinity front between the Halmahera Seram Seas. Tidally induced vertical mixing is the main process weakening the SP stratification, as suggested by a simple 1-dimensional diffusion model forced by vertical diffusivity of INDOMIX vertical microstructure profiler dataset. The transformation of SP water by vertical mixing can occur after 3 days, which is in good agreement with previously reported water mass residence times. Lateral advection plays a minor role; b) Interleaving salinity structure within the thermocline of the central Halmahera Sea and two deeper inflow channels. The interleaving salinity features within the central Halmahera Sea thermocline occurs where vertical diffusivity is relatively weak, compared to the vertical mixing at entry/exit portal that removes the interleaving salinity features. Two deeper inflow channels (about 950 m and 740 m depth) in the entry portal of the Halmahera Sea are mapped from the multi-beam echo sounder measurement, where both channels allow the renewal of SP thermocline water and salinity interleaving processes; c) Northward flow of thermocline water (100–200 m depth) in the Manipa Strait that injects Banda homogeneous salinity water into Seram Sea that erode Halmahera salty water via strong diapycnal mixing; d) Cyclonic upper layer circulation in Banda where eastward (westward) flow occurs in the northern (southern) Banda, confirmed by recent modeling study; and e) Relative salty Indian Ocean intermediate water flowing along southern margin of the Lesser Sunda Arc, within the South Java Undercurrent. Two distinct upper thermocline water, due to different source of Indonesian Throughflow (ITF) water, are found in the Banda Sea: fresher and colder water contrasting to saltier and warmer water that converge in this confluence region. Beneath it, Banda intermediate homogeneous salinity water and low dissolved oxygen water is dominant.

PERAN PEMUDA DALAM PENINGKATAN PENDAPATAN KELUARGA (STUDI KASUS PEMBUDIDAYA RUMPUT LAUT Eucheuma Cottoni DI DESA ALLANG ASAUDE KABUPATEN SERAM BAGIAN BARAT)

Development in the marine and fisheries sector is supported by opportunities for resource utilization and management that are distributed in three Fishery Management Areas (WPP), namely the Banda Sea (WPP 714), Seram Sea and Tomini Bay (WPP 715), Arafura Sea and Timor Sea (WPP 718). The fishery sector in Maluku creates opportunities for commercial businesses in the industrial sector, both in cultivation, fishing and processing, including small and large businesses. A fishery commodity that has good prospects and benefits fishing communities is seaweed cultivation. The West Seram District Government in its development policy has placed the Eucheuma cottonii seaweed commodity as a leading commodity to be developed. Youth roles are needed in cultivation activities, so it can be said that youth tend to place economic interests above other interests in determining how and where they should play a role in development. Share factor analysis is used to measure the contribution of youth income to family income and total family income is calculated by adding up youth income and family income.

Spatiotemporal Variability of Mesoscale Eddies in the Indonesian Seas

Mesoscale eddies are ubiquitous in the world ocean and well researched both globally and regionally, while their properties and distributions across the whole Indonesian Seas are not yet fully understood. This study investigates for the first time the spatiotemporal variations and generation mechanisms of mesoscale eddies across the whole Indonesian Seas. Eddies are detected from altimetry sea level anomalies by an automatic identification algorithm. The Sulu Sea, Sulawesi Sea, Maluku Sea and Banda Sea are the main eddy generation regions. More than 80% of eddies are short-lived with a lifetime below 30 days. The properties of eddies exhibit high spatial inhomogeneity, with the typical amplitudes and radiuses of 2–6 cm and 50–160 km, respectively. The most energetic eddies are observed in the Sulawesi Sea and Seram Sea. Eddies feature different seasonal cycles between anticyclonic and cyclonic eddies in each basin, especially given that the average latitude of the eddy centroid has inverse seasonal variations. About 48% of eddies in the Sulawesi Sea are highly nonlinear, which is the case for less than 30% in the Sulu Sea and Banda Sea. Instability analysis is performed using high-resolution model outputs from Bluelink Reanalysis to assess mechanisms of eddy generation. Barotropic instability of the mean flow dominates eddy generation in the Sulu Sea and Sulawesi Sea, while baroclinic instability is slightly more in the Maluku Sea and Banda Sea.

Spatial structure of turbulent mixing inferred from historical CTD datasets in the Indonesian seas

Turbulent kinetic energy dissipation rates and vertical diffusivities in the Indonesian seas are inferred from historical CTD measurements gathering for the first time data from Indonesian and international cruises. Dissipation rates are inferred from the CTD using an improved Thorpe scale method, which is validated against microstructure measurements. Elevated dissipation rates ~[10−6–10−7] m2 s−3, were observed in the near field stations, such as in the straits, narrowing passages and shallowing topography where internal tides are generated and Indonesian throughflow (ITF) is intense, while lower dissipation rates ~[10−8–10−10] m2 s−3 were observed in the far field stations and below the pycnocline. The main mixing hot spots are located in the Labani Channel and shallowing topography of the Dewakang waters for the western route of ITF, i.e. the passage that connects the north Pacific source via Sulawesi Sea, Makassar Strait and Flores Sea; in the straits of Halmahera, Lifamatola, and Buru for the eastern route of ITF, i.e. the passage that connects the south Pacific source via Halmahera Sea, Maluku Sea, Seram Sea; and in the ITF exit passages, i.e. the Lombok, Sape and Ombai Straits. The eastern route is more dissipative than the western route, which is consistent with the stronger erosion of the salinity peak of the Pacific waters along the eastern route. We found that tidal variations influence the dissipation rates and diffusivities as has been suggested from the yoyo profiling datasets. The spatial pattern of dissipation rates inferred from the high-resolution 3D hydrodynamics model output of Nagai and Hibiya (2015) shows a general agreement with the observations in the location of the mixing hot spots and suggests that the M2 internal tide is the dominant factor driving the turbulent kinetic energy dissipation rates in the Indonesian seas. Yet the model also shows a bias toward lower dissipation rate in the pycnocline, that we attribute to the lack of representation of the ITF and mesoscale circulation and a bias toward higher dissipation rate in the weak mixing region, suggesting an overestimation of the background dissipation rate in calm waters.

Analysis the Main Parameters of Seismicity in the Seram Sea, Indonesia

The Seram Sea is one of several small seas in the Indonesian archipelago and part of the Pacific Ocean which has very active tectonic activity. In this research, the data used are the recorded data of the Seram Sea earthquake and its surroundings in the period (1968-2018) with the strength of the earthquake (magnitude) ≥ 4 Richter scale (Rs). Based on the results of the analysis carried out, the seismicity parameter has the lowest b-value in the Seram Sea Region 3, which is 0.7986 and a- value is 5.8256. This occurred because this area has a greater amount of earthquakes to occur with a large magnitude due to high-stress levels. The largest Seismicity Index in the Seram Sea Region 3 is 0.0232. Region 3 in the Seram Sea has a fractal dimension (D) close to 1 indicating that in this region the source distribution in 1D. The slip ratio is close to 0.6609 which means that approximately 66.09% of the total relative shifts (slips) occur in the primary fault.

Water mass along eastern pathway of Indonesia Throughflow from a CTD Argo Float

Eastern pathway of the Indonesia Throughflow (ITF) conveys a secondary ITF inflow that brings North/South Pacific water entering interior Indonesian Seas. The transformation occurred along the Pacific water mass journey towards the Indonesian sea. For the first time since 2016, CTD Argo float measurement is available following the ITF path – along Maluku-Seram- Banda Seas, providing prime datasets to be able seen change of ITF water. This paper aims to investigate transformation of ITF water masses and the percentage of water mass contribution (with Optimum MultiParameter method) along its eastern path of ITF between Maluku – Seram and Banda Seas. The result shows that along the path, North Pacific water origin is predominant in Southern Banda Sea, but lower thermocline water of South Pacific water origin in South Maluku and Seram Sea. Large transformation of ITF water is indicated with salty upper-thermocline water in Maluku-Seram Seas, but fresh thermocline water in Banda Sea. Spatial variation of mixing layer depth and thermocline depth is also found. The percentage of the water mass contribution of the North Pacific water NPSW and NPIW gets bigger along the journey to the Banda Sea, while the dominant of SPSLTW was found in Maluku Sea and Seram Sea.

KELAYAKAN FINANSIAL USAHA PERIKANAN HUHATE DI KECAMATAN SAPARUA KABUPATEN MALUKU TENGAH

Saparua is a district in Central Maluku Regency which has 8 units of huhate (pole and line) fishing fleet and can be operated throughout the season. This condition shows that this business should be able to provide benefits, both for the owners and fishermen. However, the utilizing of skipjack resources that have exceeded the MSY value and also the substantial operational costs cause income to decline. Therefore this study aims to analyze the financial feasibility of the pole and line fisheries business in Saparua District. A survey for 5 pole and line business units in Saparua was conducted to obtain data, which were then analyzed by using several investment criteria such as NPV (Net Present Value), IRR (Internal Rate of Return), and B / C (Benefit Cost Ratio). The results show that: 1). The implementation of business management is still simple, but the tasks division among fishermen is clear. The decision is generally made by the owner. The frequency of fishing depends on the fishing season. During the west season, the fishing ground is in Banda Sea to the southern part of Seram Sea, while in the eastern season is in the northern part of Seram Sea; 2). Based on the pattern of revenue sharing, the average fishermen's income / month is lower than the minimum wage provincial (UMP) in Maluku; and 3). The highest economic benefit is achieved by the 4th pole and line unit, as well as the B / C Ratio criteria index so that it becomes a development priority because B / C Ratio shows the comparison of sacrifice (output) and results (input).

Combined Multiple Attenuation Methods and Geological Interpretation : Seram Sea Case Study 2D Marine Seismic Data

Multiple often and always appear in marine seismic data due to very high acoustic impedance contrasts. These events have undergone more than one reflection. This causes the signal to arrive back at the receiver at an erroneous time, which, in turn, causes false results and can result in data misinterpretation. Several types of multiple suppression have been studied in literature. Methods that attenuate multiples can be classified into three broad categories: deconvolution methods; filtering methods and wavefield prediction subtraction methods. The study area is situated on Seram Sea in between 131°15’E – 132°45’E and 3°0’S – 4°0’S, Seram Trough which is located beneath Seram Sea at northern part of the Banda-Arc – Australian collision zone and currently the site of contraction between Bird’s Head and Seram. This research uses predictive deconvolution and FK-filter to attenuate short period multiple from their move out, then continued by SRME method to predict multiple that cannot be attenuated from previous method, then followed by Radon transform to attenuate multiple that still left and cannot be attenuated by SRME method. The result of each method then compared to each other to see how well multiple attenuated. Predictive deconvolution and F-K filter could not give satisfactory result especially complex area where multiple in dipping event is not periodic, SRME method successfully attenuate multiple especially in near offset multiple without need subsurface information, while SRME method fails to attenuate long offset multiple, combination of SRME method and Radon transform can give satisfactory result with careful selection of the Radon transform parameters because it can obscure some primary reflectors. Based on geological interpretation, Seram Trough is built by dominant structural style of deposited fold and thrust belt. The deposited fold and thrust belt has a complexly fault geometry from western zone until eastern of seismic line.

THE EFFECTS OF DIFFERENT CHILLING METHOD AND STORAGE TIME ON THE ORGANOLEPTIC QUALITY OF FRESH SKIPJACK TUNA

Fish freshness plays an importantant role in determining quality of fish product. Organoleptic is one of sensorik method for determining fish freshness. The fish deterioration mainly affected by temperature. This study aimed to determine the best method for determining organoleptic quality of skipjact tuna based on chilling methods and storage time. Fish sampling were taken from the Seram Sea, Maluku Province. Chilling methods was done by the different ratio between the ice and fish: first was without using ice, second was ratio 1:1 and the third was ratio 1:2. The time storage were 0, 2, 4, and 6 hours.The results showed that chilling methods ratio between the ice and fish of 1:1 with 6 hours storage time provided the best organoleptic quality with eye 8.87, mucus 8.83, gill 8.67, meat 8.73, odour 8.80, and texture 8.86. Keywords: chilling methods, organoleptics, skipjact tuna

Morphometric Relationship, Growth, and Condition Factor of Flyingfish, Hirundicththys oxycephalus during spawning season

Flyingfish, Hirundichthys oxycephalus together with its congener species has become a major artisanal fishery resource from the Seram Sea, an area between Seram and Papua Island. However, biological information about this species has been poorly documented. Our current study focused on the growth and morphometric relationships of spawning cohorts during spawning season (June to October 2013). Flyingfish which were trapped in bale-bale, an egg aggregation device for flying fish, were collected offshore of the Southeastern Seram Sea. Total samples of 1693 with Fork Length (FL) ranged from 156.15mm to 245.52mm and total weight from 53.15gr to 115.45gr. Von Bertalanffy growth functions (L∞) for-pooled sexes were FL = 251mm [1-e (1.82 (t+0.060)], K=1.82 and t0 = 0.060. Morphometrically, significant differences were observed for all individuals between sexes (F=14.20, P=0.0002), sampling locations (F=88.48 P<0.0001) and sampling period (F=138.84, P<0.0001). Condition factor of the fish generally declined in July-August. During spawning season, this fish tended to form single spawning cohort. The results of this study provide a significant understanding of the life history of this valuable fish inhabiting this particular region that rarely receives scientific investigation. For management purposes, harvesting eggs including broodstocks will lead to critical population depletion.

Tidal mixing signatures in the Indonesian seas from high‐resolution sea surface temperature data

AbstractThe presence of significant tidal mixing in the Indonesian seas is well established from both observations and numerical modeling. One indicator is a clear spring‐neap cycle in satellite sea surface temperature (SST) measurements, as first shown by Ffield and Gordon. Their early results are here updated with SST data of considerably higher spatial and temporal resolution. The largest fortnightly signals are found to be localized to relatively small straits, channels, and sills, while the deep basin of the Banda Sea displays little significant signal. A broader region of somewhat enhanced signal surrounds the Seram Sea. The high resolution of the modern SST data is especially critical for mapping the complex fortnightly signals that arise in, and especially south of, the major straits of the Lesser Sunda Island chain.

PEMODELAN DINAMIKA ARUS PERAIRAN INDONESIA YANG DISEBABKAN OLEH ANGIN

Research on current dynamics modelling in Indonesian waters with wind employed as independent variable has been observed. The purpose of this study was to model the hydrodynamic equations due to the influence of the wind in Indonesia waters in the form of visualization described consisting of wind circulation pattern and pattern of current movement in the west and east monsoon season. To analyze the data obtained during the study, researchers used a descriptive approach. The results showed that the west wind season (December, January, and February) blow from the northeast to the southwest then turning southeast. Whereas the east wind season (June, July, and August) blows from the southeast to the northwest and then turn to the northeast. On the surface layer shows the current movement in general follows the movement of the wind direction in which the current speed is very dominant occurred in some waters, such as the Karimata Strait, the Java Sea, the South China Sea, and the Arafuru Sea. The dominant current velocity in the layer of 100-200 m in the water of eastern equator and the South China Sea in the west season has recorded a current speed reaches 20 cm / s. while in the east monsoon which occurs in the equatorial waters of the eastern part, in the Maluku Sea, the Seram Sea and nearby the Arafuru Sea current velocity reaches 40cm / s.

The westward intrusion of south Pacific water at the western tip of the New Guinea Island

Fromthe eastern Indonesian cruise from November 14 to 23, 2007, CTD (conductivity, temperature, depth profiler) /ADCP (acoustic Doppler current profiler)casting and seawater sampling were done at 25 stations around Waigeo Island near New Guinea Island. It was found overall westward intrusion of the south Pacific waters into the Seram Sea and southward spreading of the north and south Pacific waters into the Seram Sea. There is westward residual flow along the channel between Waigeo and New Guinea within upper 200 m with the maximum speed up to 50 cm/s, and much weaker eastward flow in the lower layer (< 10 cm/s) due to blocking by the shallow sill at the west of the Dampier Strait. The abrupt change of bottom topography induces active horizontal and vertical mixing which results in a three-layered current system with a major through-flow of −0.99 Sv (Sv = 106 m3/s) into the Seram Sea; the transports in the upper and the lower layers are −1.14 Sv and −0.24 Sv (westward), respectively, and in the middle there is a return flow with the transport of +0.39 Sv (eastward).