scholarly journals The Strong Downwelling (Upwelling) Impact on Small Pelagic Fish Production During the 2016 (2019) Negative (Positive) Indian Ocean Dipole Events in the Eastern Indian Ocean off Java

2020 ◽  
Author(s):  
Jonson Lumban-Gaol ◽  
Eko Siswanto ◽  
Nyoman Metah N. Natih ◽  
I Wayan Nurjaya ◽  
Mochammad Tri Hartanto ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Phytoplankton Biomass ◽  
Pelagic Fish ◽  
Eastern Indian Ocean ◽  
Fish Production ◽  
Small Pelagic Fish ◽  
Field Surveys ◽  
Chl A ◽  
Positive Indian Ocean Dipole ◽  
The Impact

Although researchers have investigated widely the impact of IOD phases on human lives, only a few have examined such impacts on fisheries. In this study, we analyzed the influence of negative (positive) of IOD on a chlorophyll a (Chl-a) concentration as an indicator of phytoplankton biomass and small pelagic fish production in the eastern Indian Ocean (EIO) off Java. We also conducted field surveys in the EIO off Palabuhanratu Bay at the peak (October) and the end (December) of the 2019 positive IOD phase. Our findings show that the Chl-a concentration had a strong and robust association with the 2016 (2019) negative (positive) IOD phases. The negative (positive) anomalous Chl-a concentration in the EIO off Java associated with the negative (positive) IOD phase induced strong downwelling (upwelling), leading to the preponderant decrease (increasing) of small pelagic fish production in the EIO off Java.

scholarly journals Impact of the Strong Downwelling (Upwelling) on Small Pelagic Fish Production during the 2016 (2019) Negative (Positive) Indian Ocean Dipole Events in the Eastern Indian Ocean off Java

Climate ◽  
2021 ◽  
Vol 9 (2) ◽  
pp. 29
Author(s):  
Jonson Lumban-Gaol ◽  
Eko Siswanto ◽  
Kedarnath Mahapatra ◽  
Nyoman Metta Nyanakumara Natih ◽  
I Wayan Nurjaya ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Indian Ocean Dipole ◽  
Pelagic Fish ◽  
Eastern Indian Ocean ◽  
Fish Production ◽  
Small Pelagic Fish ◽  
Field Surveys ◽  
Chl A ◽  
Positive Indian Ocean Dipole ◽  
The Impact

Although researchers have investigated the impact of Indian Ocean Dipole (IOD) phases on human lives, only a few have examined such impacts on fisheries. In this study, we analyzed the influence of negative (positive) IOD phases on chlorophyll a (Chl-a) concentrations as an indicator of phytoplankton biomass and small pelagic fish production in the eastern Indian Ocean (EIO) off Java. We also conducted field surveys in the EIO off Palabuhanratu Bay at the peak (October) and the end (December) of the 2019 positive IOD phase. Our findings show that the Chl-a concentration had a strong and robust association with the 2016 (2019) negative (positive) IOD phases. The negative (positive) anomalous Chl-a concentration in the EIO off Java associated with the negative (positive) IOD phase induced strong downwelling (upwelling), leading to the preponderant decrease (increase) in small pelagic fish production in the EIO off Java.

scholarly journals An Evaluation of the Impact of Pandemic Driven Lockdown on the Phytoplankton Biomass Over the North Indian Ocean Using Observations and Model

2021 ◽  
Vol 8 ◽  
Author(s):  
Vivek Seelanki ◽  
Vimlesh Pant
Keyword(s):  
Indian Ocean ◽  
Phytoplankton Biomass ◽  
Arabian Sea ◽  
Anthropogenic Activities ◽  
Simulated Data ◽  
North Indian Ocean ◽  
Biogeochemical Model ◽  
Chl A ◽  
The North ◽  
The Impact

The unprecedented nationwide lockdown due to the ‘coronavirus disease 2019’ (COVID-19) affected humans and the environment in different ways. It provided an opportunity to examine the effect of reduced transportation and other anthropogenic activities on the environment. In the current study, the impact of lockdown on chlorophyll-a (Chl-a) concentration, an index of primary productivity, over the northern Indian Ocean (IO), is investigated using the observations and a physical-biogeochemical model. The statistics of model validation against observations shows a correlation coefficient of 0.85 (0.89), index of agreement as 0.90 (0.91). Root mean square error of 0.45°C (0.50°C) for sea surface temperature over the Bay of Bengal (BoB) (Arabian Sea, AS) is observed. The model results are analyzed to understand the upper-oceanic physical and biological processes during the lockdown. A comparison of the observed and model-simulated data during the lockdown period (March–June, 2020) and pre-pandemic period (March–June, 2019) shows significant differences in the physical (temperature and salinity) and biogeochemical (Chl-a concentration, nutrient concentration, and dissolved oxygen) parameters over the western AS, western BoB, and regions of Sri Lanka. During the pandemic, the reduced anthropogenic activities lead to a decrease in Chl-a concentration in the coastal regions of western AS and BoB. The enhanced aerosol/dust transport due to stronger westerly winds enhanced phytoplankton biomass in the western Arabian Sea (WAS) in May–June of the pandemic period.

scholarly journals Upwelling Impact on Sardinella lemuru during the Indian Ocean Dipole in the Bali Strait, Indonesia

Fishes ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 8
Author(s):  
Daduk Setyohadi ◽  
Umi Zakiyah ◽  
Abu Bakar Sambah ◽  
Adi Wijaya
Keyword(s):  
Indian Ocean ◽  
Indian Ocean Dipole ◽  
Phytoplankton Biomass ◽  
Satellite Images ◽  
Sea Surface ◽  
Negative Phase ◽  
Field Surveys ◽  
The Indian Ocean ◽  
The Government ◽  
The Impact

Understanding the impact of Indian Ocean Dipole (IOD) on fishery around Indonesia is important as the fishery resources are small compared to the demand. In this study, we analyzed the effect of positive and negative phases of IOD on chlorophyll-a concentration and the catch of Sardinella lemuru in the Bali Strait. Data are based on field surveys in the Bali Strait during the positive and negative phase of IOD and Sea Surface Temperature (SST) and Sea Surface Chlorophyll (SSC) obtained from the analysis of satellite images. The results suggest that SSC concentration in the strait significantly correlates with the positive and negative phase of IOD, possibly through a change of upwelling and downwelling there. It is suggested that the change of phytoplankton biomass due to positive IOD would result in an increase of Sardinella lemuru in the Bali Strait. This research has direct implications as important information for the government in planning lemuru fisheries management in the Bali Strait based on oceanographic studies and climate phenomena.

scholarly journals A biological Indian Ocean Dipole event in 2019

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Wei Shi ◽  
Menghua Wang
Keyword(s):  
Biological Activity ◽  
Indian Ocean ◽  
Indian Ocean Dipole ◽  
Infrared Imaging ◽  
Equatorial Indian Ocean ◽  
The West ◽  
Indian Ocean Dipole Event ◽  
Chl A ◽  
Positive Indian Ocean Dipole ◽  
Dipole Response

AbstractThe 2019 positive Indian Ocean Dipole (IOD) event in the boreal autumn was the most serious IOD event of the century with reports of significant sea surface temperature (SST) changes in the east and west equatorial Indian Ocean. Observations of the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi National Polar-orbiting Partnership (SNPP) between 2012 and 2020 are used to study the significant biological dipole response that occurred in the equatorial Indian Ocean following the 2019 positive IOD event. For the first time, we propose, identify, characterize, and quantify the biological IOD. The 2019 positive IOD event led to anomalous biological activity in both the east IOD zone and west IOD zone. The average chlorophyll-a (Chl-a) concentration reached over ~ 0.5 mg m−3 in 2019 in comparison to the climatology Chl-a of ~ 0.3 mg m−3 in the east IOD zone. In the west IOD zone, the biological activity was significantly depressed. The depressed Chl-a lasted until May 2020. The anomalous ocean biological activity in the east IOD zone was attributed to the advection of the higher-nutrient surface water due to enhanced upwelling. On the other hand, the dampened ocean biological activity in the west IOD zone was attributed to the stronger convergence of the surface waters than that in a normal year.

scholarly journals DISTRIBUSI DAN POTENSI SUMBER DAYA IKAN PELAGIS DI WILAYAH PENGELOLAAN PERIKANAN NEGARA REPUBLIK INDONESIA 573 (WPP NRI 573) SAMUDERA HINDIA

2017 ◽  
Vol 23 (1) ◽  
pp. 47
Author(s):  
Asep Ma'mun ◽  
Asep Priatna ◽  
Thomas Hidayat ◽  
Nurulludin Nurulludin
Keyword(s):  
Indian Ocean ◽  
Distribution Pattern ◽  
Sustainable Management ◽  
Acoustic Method ◽  
Pelagic Fish ◽  
Small Pelagic Fish ◽  
Fish Size ◽  
Fish Resources ◽  
Needed Information ◽  
Pelagic Fisheries

Pengelolaan perikanan tangkap yang lestari membutuhkan informasi potensi dan pola penyebaran sumber daya ikan yang dimanfaatkan. Penelitian ini bertujuan untuk mengetahui distribusi dan potensi sumber daya ikan pelagis di WPP NRI 573 (perairan Samudera Hindia) dengan metode akustik. Hasil penelitian menunjukan, penyebaran densitas cukup tinggi untuk ikan pelagis ditemukan di perairan selatan Pangandaran hingga wilayah Jogjakarta. Sumber daya ikan pelagis kecil yang terdeteksi didominasi oleh ukuran ikan dengan kisaran panjang antara 25-28 cm dan ikan pelagis besar di dominasi oleh ukuran ikan 28-31 cm. Nilai rata-rata kepadatan stok untuk ikan pelagis kecil 0,041 ton/km2 dan ikan pelagis besar sebesar 0,14 ton/ km2. Potensi lestari ikan pelagis kecil sebesar 292.092 ton/tahun dan ikan pelagis besar sebesar 505.941 ton/tahun. Nilai tersebut dapat dijadikan dasar dalam upaya pengelolaan dan pemanfaatan perikanan pelagis.The sustainable management is needed information on the stock and distribution pattern of fish.This study aims to determine distribution and potential of fish resources especially for pelagic species in FMA 573 (Indian Ocean) by using acoustic method. Result of research indicated that, high density for pelagic fish found in south Pangandaran to Jogjakarta. The results obtained also that, the detected small pelagic fish were dominated by the fish size ranged between 25-28 cm and large pelagic fish was dominated by fish size of 28-31cm.The average of the stock density for small pelagic fish was 0,041 ton/km2 and large pelagic fish of 0.14 ton/km2.The sustainable potential of the small pelagic fish amounted to 292.092 ton/year and the large pelagic fish amounted to 505.941 ton/year. These values can be used as the basic management and utilization of pelagic fisheries in the waters region.

scholarly journals Characteristics Fishing Areas of Bigeye Tuna (Thunnus Obesus) in Depth of 155 m Based on Remotely Sensed Data

2020 ◽  
Vol 5 (1) ◽  
pp. 62-70
Author(s):  
Achmad Fachruddin-Syah ◽  
Jonson Lumban Gaol ◽  
Mukti Zainuddin ◽  
Nadela Rista Apriliya ◽  
Dessy Berlianty ◽  
...  
Keyword(s):  
Indian Ocean ◽  
Remotely Sensed ◽  
Eastern Indian Ocean ◽  
Bigeye Tuna ◽  
Remotely Sensed Data ◽  
Surface Salinity ◽  
Chl A ◽  
Fishing Vessels ◽  
Thunnus Obesus ◽  
Daily Data

Bigeye tuna (Thunnus obesus) is one of the commercially important pelagic species that caught mostly in the eastern Indian Ocean. This species prefers to stay close, and is usually below the thermocline layer. Remotely sensed data was used to determine the characteristics of Bigeye tuna fishing areas at a depth of 155 meter. Fishing vessels for Bigeye tuna were obtained from vessel monitoring systems (VMS) from January through December, 2015-2016. Daily data on sub-surface temperature (SST), sub-surface chlorophyll-a concentration (SSC), and sub-surface salinity (SSS) were obtained from the INDESO Project website. All oceanographic parameter data were selected at a depth of 155 m. The position of Bigeye tuna and oceanographic data were then grouped into 2 group monsoon, southeast monsoon (April – September) and northwest monsoon (October – March). The results showed that, during the southeast and northwest monsoon, Bigeye tuna mostly found in SSC of 0.03 – 0.05 mg/m3, SST of 16° - 18°C and salinity of 34 psu. These results showed that at depth of 155 m, Bigeye Tuna prefers to stay in small chl-a (0.03 – 0.04 mg/m3), low SST (16° - 18°C) and salinity of 34 psu. These information were essential and could be used to support fisheries management decisions especially for Bigeye Tuna in the eastern Indian Ocean.

Modulation of Australian Precipitation by Meridional Gradients in East Indian Ocean Sea Surface Temperature

2009 ◽  
Vol 22 (21) ◽  
pp. 5597-5610 ◽  
Author(s):  
Caroline C. Ummenhofer ◽  
Alexander Sen Gupta ◽  
Andréa S. Taschetto ◽  
Matthew H. England
Keyword(s):  
Indian Ocean ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Sea Surface ◽  
Eastern Indian Ocean ◽  
Southeastern Australia ◽  
The Impact ◽  
Sst Gradient ◽  
Meridional Sst Gradient ◽  
Australian Rainfall

Abstract This study explores the impact of meridional sea surface temperature (SST) gradients across the eastern Indian Ocean on interannual variations in Australian precipitation. Atmospheric general circulation model (AGCM) experiments are conducted in which the sign and magnitude of eastern Indian Ocean SST gradients are perturbed. This results in significant rainfall changes for western and southeastern Australia. A reduction (increase) in the meridional SST gradient drives a corresponding response in the atmospheric thickness gradients and results in anomalous dry (wet) conditions over Australia. During simulated wet years, this seems to be due to westerly anomalies in the thermal wind over Australia and anomalous onshore moisture advection, with a suggestion that the opposite occurs during dry conditions. Thus, an asymmetry is seen in the magnitude of the forced circulation and precipitation response between the dry and wet simulations. To assess the relative contribution of the SST anomalies making up the meridional gradient, the SST pattern is decomposed into its constituent “poles,” that is, the eastern tropical pole off the northwest shelf of Australia versus the southern pole in the central subtropical Indian Ocean. Overall, the simulated Australian rainfall response is linear with regard to the sign and magnitude of the eastern Indian Ocean SST gradient. The tropical eastern pole has a larger impact on the atmospheric circulation and Australian precipitation changes relative to the southern subtropical pole. However, there is clear evidence of the importance of the southern pole in enhancing the Australian rainfall response, when occurring in conjunction with but of opposite sign to the eastern tropical pole. The observed relationship between the meridional SST gradient in the eastern Indian Ocean and rainfall over western and southeastern Australia is also analyzed for the period 1970–2005. The observed relationship is found to be consistent with the AGCM results.

KAPASITAS PENANGKAPAN IKAN PELAGIS KECIL DI PERAIRAN PANTAI BARAT SULAWESI SELATAN (FISHING CAPACITY OF SMALL PELAGIC FISH IN OF WEST COAST OF SOUTH SULAWESI)

2016 ◽  
Vol 1 (2) ◽  
pp. 117 ◽  
Author(s):  
Alfa Nelwan
Keyword(s):  
West Coast ◽  
Fishing Effort ◽  
Pelagic Fish ◽  
Production Data ◽  
Fish Production ◽  
Beach Seine ◽  
Small Pelagic Fish ◽  
South Sulawesi ◽  
Gill Net ◽  
Development Analysis

Kapasitas penangkapan adalah ukuran kemampuan yang dikerahkan oleh berbagai jenis unit penangkapan ikan yang tergabung sebagai suatu armada penangkapan ikan untuk memperoleh hasil tangkapan. Penelitian ini menganalisis trend dan kapasitas penangkapan ikan pelagis kecil di perairan pantai barat Sulawesi Selatan. Delapan jenis alat penangkap yang signifikan di Selat Makassar, perairan barat Provinsi Sulawesi Selatan adalah payang, pukat pantai, pukat cincin, jaring insang hanyut, jaring lingkar, jaring insang tetap, bagan perahu dan bagan tancap.  Produksi dari 8 unit penangkapan berdasarkan 6 jenis ikan pelagis kecil, yaitu (1) kembung (Rastrelliger sp), (2) layang (Decapterus sp), (3) lemuru (Sardinella longiceps), (4) selar (Selaroides spp), (5) tembang (Sardinella  fimbriata), (6) teri (Stolephorus spp). Total upaya penangkapan ikan tahunan dari kedelapan jenis unit penangkapan ikan tersebut dihitung untuk kurun waktu selama 20 tahun (1987-2006) dengan menerapkan standardisasi berdasarkan kemampuan setiap jenis unit penangkapan ikan.  Analisis dilakukan untuk mengidentifikasi trend CPUE dan kapasitas penangkapan ikan pelagis kecil menggunakan metode Peak to Peak Analysis di tiga zona perairan pantai, yaitu perairan laut dangkal  (zona A), perairan bentuk teluk (zona B) dan perairan laut dalam (zona C), Tren CPUE di ketiga zona menunjukkan cenderung menurun dalam kurun waktu 30 tahun, dimana tren menurun CPUE di zona C menunjukkan lebih besar dibandingkan zona lainnya.  Kapasitas penangkapan di zona A, perlu mereduksi jumlah unit penangkapan sebesar 6%, sedangkan di zona B sebesar 5% dan zona C sebesar 11% untuk mencapai produksi optimal.Fishing capacity can be regarded as a total mobilized capability made by fishing fleet to produce catch. This research analyze trend and fishing capacities of small pelagic fish in off west coast of South Sulawesi. There are 8 significant fishing unit operated in off west coast of South Sulawesi ; these are  payang, beach seine, purse seine, drift gill net, encircling gillnet, fixed gill net, boat liftnet, fixed liftnet.  The fish production data cover 6 types of fish, i.e. Indian mackerel, anchovy, sardines, scads, and trevally caught by 8 types fishing unit. Annual fishing effort and CPUE over a period of 30 years (1977-2006) were calculated after a standardization considering variability in capture capability and fisheries development.  Analysis was conducted for identifyng CPUE trend and fishing capacities of small pelagic fish using Peak to Peak Analysis. The study area was divided into three regions, i.e, around Spermonde Island  (zone A), off Polman and Pinrang district (zone B) and off Majene dan Mamuju district (zone C).  CPUE trend in three water zone showed to decrease for 30 year of period, where decreasing CPUE trend at zone C was higher than other zones.  Fishing capacities in zone A need to be reduced of fishing effort for  6%, whereas in zone B was 5% and zone C was 11%.

scholarly journals VARIABILITY OF SEA SURFACE TEMPERATURE (SST) AND CHLOROPHYLL-A (CHL-A) CONCENTRATIONS IN THE EASTERN INDIAN OCEAN DURING THE PERIOD 2002–2017

2019 ◽  
Vol 16 (1) ◽  
pp. 55
Author(s):  
Michelia Mashita ◽  
Jonson Lumban-Gaol
Keyword(s):  
Indian Ocean ◽  
Surface Temperature ◽  
Sea Surface Temperature ◽  
Chlorophyll A ◽  
Sea Surface ◽  
Asia Pacific ◽  
Eastern Indian Ocean ◽  
Positive Anomaly ◽  
Chl A ◽  
Annual Variability

We analysed the variability of sea surface temperature (SST) and chlorophyll-a concentration (Chl-a) in the eastern Indian Ocean (EIO). We used monthly mean Chl-a and SST data with a 4-km spatial resolution derived from Level-3 Aqua Moderate-resolution Imaging Spectroradiometer (MODIS) distributed by the Asia-Pacific Data-Research Center (APDRC) for the period 2002–2017. Wavelet analysis shows the annual and interannual variability of SST and Chl-a concentration in the EIO. The annual variability of SST and Chl-a is influenced by monsoon systems. During a southeast monsoon, SST falls while Chl-a increases due to upwelling. The annual variability of SST and Chl-a is also influenced by the Indian Ocean Dipole (IOD). During positive phases of the IOD (2006, 2012 and 2015), there was more intense upwelling in the EIO caused by the negative anomaly of SST and the positive anomaly of Chl-a concentration.

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