scholarly journals Mapping spatial-temporal skipjack tuna habitat as a reference for Fish Aggregating Devices (FADs) settings in Makassar Strait, Indonesia

2021 ◽  
Vol 22 (9) ◽  
Author(s):  
RACHMAT HIDAYAT ◽  
MUKTI ZAINUDDIN ◽  
ACHMAR MALLAWA ◽  
MUZZNEENA AHMAD MUSTAPHA ◽  
A. RANI SAHNI PUTRI
Keyword(s):  
Economic Value ◽  
Additive Model ◽  
Sea Surface ◽  
Habitat Characteristics ◽  
Cumulative Distribution ◽  
Skipjack Tuna ◽  
Empirical Cumulative Distribution Function ◽  
Pelagic Habitat ◽  
High Consistency ◽  
Fish Aggregating Devices

Abstract. Hidayat R, Zainuddin M, Mallawa A, Mustapha MA, Putri ARS. 2021. Mapping spatial-temporal skipjack tuna habitat as a reference for Fish Aggregating Devices (FADs) settings in Makassar Strait, Indonesia. Biodiversitas 22: 3637-3647. Skipjack tuna (Katsuwonus pelamis) has a high economic value in the international market. Catching skipjack tuna using fish aggregating devices (FADs) without knowing its habitat characteristics can damage the ecosystem. This study aimed to determine suitable fishing areas for setting skipjack’s FADs. The data used included that on catch, sea surface temperature (SST), and sea surface chlorophyll-a (SSC) in the Makassar Strait obtained for 2017-2019. The generalized additive model (GAM) and empirical cumulative distribution function (ECDF) analyses were used to investigate the skipjack’s tuna habitat. A pelagic habitat index (PHI), with PHI > 75%, was applied to determine suitable FAD positions. The gravity center of the skipjack tuna habitat for ten months (January-October 2020) was calculated to validate the model’s results. The results showed that the optimum SST range was from 28.78°C to 31.25°C, while the SSC from 0.18 to 0.28 mg m-3. The best skipjack habitats in the southern Makassar Strait are criterion 4 (PHI > 90%) and criterion 3 (PHI = 85-90%), having a relatively high consistency of the average PHI values. These results can help determine the optimal positions for setting FADs to benefit the global management and sustainable development of skipjack tuna fisheries.

scholarly journals Mapping potential fishing zones for skipjack tuna in the southern Makassar Strait, Indonesia, using Pelagic Habitat Index (PHI)

2021 ◽  
Vol 22 (7) ◽  
Author(s):  
ANDI RANI SAHNI PUTRI ◽  
Mukti Zainuddin ◽  
MUSBIR MUSBIR ◽  
RACHMAT HIDAYAT ◽  
MUZZNEENA AHMAD MUSTAPHA
Keyword(s):  
Spatial Pattern ◽  
Generalized Additive Models ◽  
Additive Models ◽  
Fish Distribution ◽  
Cumulative Distribution ◽  
Conservation Strategies ◽  
Skipjack Tuna ◽  
Empirical Cumulative Distribution Function ◽  
Pelagic Habitat ◽  
Potential Fishing Zone

Abstract. Putri ARS, Zainuddin M, Musbir, Mustapha MA, Hidayat R. 2021. Mapping potential fishing zones for skipjack tuna in the southern Makassar Strait, Indonesia, using Pelagic Habitat Index (PHI). Biodiversitas 22: 3037-3045. Southern Makassar Strait is one of the potential fishing grounds for skipjack tuna in the Indonesian waters. Oceanographic factors become the primary factors that limit the distribution and abundance of fish. The study aimed to identify the relationship between fish distribution with sea surface temperature (SST) and primary productivity (PP) and map out the potential fishing grounds of skipjack tuna in the southern Makassar Strait. It used pelagic habitat index (PHI) analysis, which is strengthened by the results of correlation analysis in the form of generalized additive models (GAM) and Empirical cumulative distribution function (ECDF) analysis. The results showed that the distribution of skipjack tuna was significantly associated with the preferred range of SST 29-30.5°C and PP 350-400 mg C/m2/day. The potential fishing zone is well established near the coast to offshore of Barru and Polman waters (3°-6°S and 117°-119°E), with the peak season in May and October. The spatial pattern of potential fishing grounds for skipjack fishing is associated with hotspots (oceanographic preference), leading to increased feeding opportunities. This study suggests that the spatial pattern of high potential fishing zones could improve fishing, management, and conservation strategies along the southern Makassar Strait.

scholarly journals STATUS KEBERLANJUTAN PERIKANAN HUHATE BERDASARKAN ASPEK BIOLOGI DI PPI DUFA-DUFA KOTA TERNATE

1970 ◽  
Vol 10 (1) ◽  
pp. 117-116
Author(s):  
Irham . ◽  
Amirul Karman ◽  
Kusdi Hi Iksan
Keyword(s):  
Size Structure ◽  
Economic Value ◽  
Fork Length ◽  
Pelagic Fish ◽  
Fishing Ground ◽  
Skipjack Tuna ◽  
Katsuwonus Pelamis ◽  
Strategic Location ◽  
Catch Composition ◽  
Fish Aggregating Devices

ABSTRACTTernate Island lies in a strategic location as it is situated in the middle of  the main fishing ground for skipjack (Katsuwonus pelamis) fishing using pole and line (huhate) and fish aggregating devices (FADs). As typical pelagic fish, skipjack that is gathered near the water surface is the younger fish, likewise the ones which are caught around FADs. Therefore, this fishing method has caused serious problem due to the domination of young fish and increasing bycatch and discard. The objective of this research is to analyze the size structure of the fork length, appropriate size for catching, catch composition, bycatch and discard level. Pole and line catch samples were collected in 3 months fromMay to July 2018. The results show that in average, skipjack tuna caught in the study location was undersize. The total catch is predominantly targeted fish which has a higher economic value compared to bycatch and discarded fish. Even though bycatch in the pole and line fisheries are low, reduction efforts are still required. which can be done by sorting bycatch and unwanted fish then discard it into the sea when the fish is still alive.Keywords: biology, pole and line, sustainability status, Ternate City ABSTRAKPosisi Pulau Ternate sangat strategis karena berada di tengah perairan yang menjadi daerah operasi penangkapan cakalang (Katsuwonus pelamis) dengan alat tangkap huhate (pole and line) yang dibantu dengan penggunaan rumpon. Sebagaimana ikan pelagis lainnya,  ikan-ikan cakalang yang berkumpul di lapisan permukaan air cenderung tergolong ikan-ikan muda. Oleh karena itu, cakalang yang tertangkap di sekitar rumpon juga cenderung ikan-ikan yang masih muda. Fenomena ini menyebabkan munculnya sebuah masalah besar, yaitu dominasi ikan-ikan muda, selain itu juga sering tertangkap ikan yang bukan target tangkap yang terdiri dari bycatch dan discards. Tujuan dari penelitian ini adalah menganalisis struktur ukuran panjang cagak dan ukuran cakalang layak tangkap, komposisi hasil tangkapan, persentase bycatch dan discards. Sampel hasil tangkapan huhate dikumpulkan selama 3 bulan (Mei sampai Juli 2018). Hasil penelitian menunjukkan bahwa rataan cakalang di lokasi penelitian didominasi ukuran belum layak tangkap. Total hasil tangkapan didominasi ikan target, sementara itu bycatch yang tertangkap memiliki nilai ekonomis yang baik dan tidak ditemukan discards. Walaupun bycatch pada perikanan huhate rendah namun usaha-usaha untuk meminimumkan tetap perlu dilakukan. Salah satu usaha yang bisa dilakukan adalah menyortir hasil tangkapan, ada apabila ada ikan yang akan dibuang ke laut, dilakukan dalam keadaan masih hidup.Kata Kunci: Biologi, huhate (pole and line), status keberlanjutan, Kota Ternate

scholarly journals Detection of pelagic habitats and abundance of skipjack tuna in relation to the environment in the Indian Ocean around Sri Lanka

2019 ◽  
Author(s):  
Thushani Suleka Madhubha Elepathage ◽  
Danling Tang
Keyword(s):  
Monsoon Season ◽  
Remote Sensing Data ◽  
Cumulative Distribution ◽  
Optimum Level ◽  
Skipjack Tuna ◽  
Chl A ◽  
Catch Data ◽  
South West Monsoon ◽  
Pelagic Habitat ◽  
Fish Catch

Using remote sensing data of sea surface temperature (SST), chlorophyll-a (Chl-a) together with catch data, the pelagic hotspots of Skipjack tuna (SKPJ) were identified. MODIS/Aqua satellite data and the fish catch data were obtained during 2002-2016 period. Empirical cumulative distribution frequency (ECDF) model of satellite-based oceanographic data in relation to skipjack fishing was used for the initial statistical analysis and the results showed that key pelagic habitat corresponded mainly with the 0.4 – 0.7 mg m-3 Chl-a concentration. Chl-a represents the phytoplankton that attracts the food items of SKPJ like zooplankton and nekton The favorable SST range for SKPJ is 26 - 27 0C which provides suitable thermocline and an optimum level of upwelling to circulate nutrients needed for the primary production. The high total catches and CPUEs were found within the months of September to December and the optimum levels of Chl-a, SST also were observed in similar months. Hence, the South-West monsoon season was identified as the best and peak season of SKPJ fisheries. SST and Chl-a are important indicators to detect the habitats of SKPJ and the maps prepared can be used in the future to cost-effectively and efficiently identify and demarcate the biological conservation regions or fisheries zones of SKPJ. According to GAM the 0.3 - 0.6 mg m-3 Chl-a, 28 - 28.5 0C SST in Western and 0.25 - 0.3 mg m-3 Chl-a and 28.5 - 28.80C SST in Eastern were found as highly correlated predictor variables value ranges with SKPJ abundance. The deviances explained in above areas in GAM were 90.8% and 61.4% respectively. The GAM was considered as a robustly dealing method with nonlinear relationships and it can be used to model the fish catch abundance with influencing variables significantly since it could predict the CPUE values greater than 90% similarly to nominal CPUEs in both subregions of the study area.

scholarly journals Detection of pelagic habitats and abundance of skipjack tuna in relation to the environment in the Indian Ocean around Sri Lanka

2019 ◽  
Author(s):  
Thushani Suleka Madhubha Elepathage ◽  
Danling Tang
Keyword(s):  
Monsoon Season ◽  
Remote Sensing Data ◽  
Cumulative Distribution ◽  
Optimum Level ◽  
Skipjack Tuna ◽  
Chl A ◽  
Catch Data ◽  
South West Monsoon ◽  
Pelagic Habitat ◽  
Fish Catch

Using remote sensing data of sea surface temperature (SST), chlorophyll-a (Chl-a) together with catch data, the pelagic hotspots of Skipjack tuna (SKPJ) were identified. MODIS/Aqua satellite data and the fish catch data were obtained during 2002-2016 period. Empirical cumulative distribution frequency (ECDF) model of satellite-based oceanographic data in relation to skipjack fishing was used for the initial statistical analysis and the results showed that key pelagic habitat corresponded mainly with the 0.4 – 0.7 mg m-3 Chl-a concentration. Chl-a represents the phytoplankton that attracts the food items of SKPJ like zooplankton and nekton The favorable SST range for SKPJ is 26 - 27 0C which provides suitable thermocline and an optimum level of upwelling to circulate nutrients needed for the primary production. The high total catches and CPUEs were found within the months of September to December and the optimum levels of Chl-a, SST also were observed in similar months. Hence, the South-West monsoon season was identified as the best and peak season of SKPJ fisheries. SST and Chl-a are important indicators to detect the habitats of SKPJ and the maps prepared can be used in the future to cost-effectively and efficiently identify and demarcate the biological conservation regions or fisheries zones of SKPJ. According to GAM the 0.3 - 0.6 mg m-3 Chl-a, 28 - 28.5 0C SST in Western and 0.25 - 0.3 mg m-3 Chl-a and 28.5 - 28.80C SST in Eastern were found as highly correlated predictor variables value ranges with SKPJ abundance. The deviances explained in above areas in GAM were 90.8% and 61.4% respectively. The GAM was considered as a robustly dealing method with nonlinear relationships and it can be used to model the fish catch abundance with influencing variables significantly since it could predict the CPUE values greater than 90% similarly to nominal CPUEs in both subregions of the study area.

scholarly journals Detection of pelagic habitats and abundance of skipjack tuna in relation to the environment in the Indian Ocean around Sri Lanka

2019 ◽  
Author(s):  
Thushani Suleka Madhubha Elepathage ◽  
Danling Tang
Keyword(s):  
Monsoon Season ◽  
Remote Sensing Data ◽  
Cumulative Distribution ◽  
Optimum Level ◽  
Skipjack Tuna ◽  
Chl A ◽  
Catch Data ◽  
South West Monsoon ◽  
Pelagic Habitat ◽  
Fish Catch

Using remote sensing data of sea surface temperature (SST), chlorophyll-a (Chl-a) together with catch data, the pelagic hotspots of Skipjack tuna (SKPJ) were identified. MODIS/Aqua satellite data and the fish catch data were obtained during 2002-2016 period. Empirical cumulative distribution frequency (ECDF) model of satellite-based oceanographic data in relation to skipjack fishing was used for the initial statistical analysis and the results showed that key pelagic habitat corresponded mainly with the 0.4 – 0.7 mg m-3 Chl-a concentration. Chl-a represents the phytoplankton that attracts the food items of SKPJ like zooplankton and nekton The favorable SST range for SKPJ is 26 - 27 0C which provides suitable thermocline and an optimum level of upwelling to circulate nutrients needed for the primary production. The high total catches and CPUEs were found within the months of September to December and the optimum levels of Chl-a, SST also were observed in similar months. Hence, the South-West monsoon season was identified as the best and peak season of SKPJ fisheries. SST and Chl-a are important indicators to detect the habitats of SKPJ and the maps prepared can be used in the future to cost-effectively and efficiently identify and demarcate the biological conservation regions or fisheries zones of SKPJ. According to GAM the 0.3 - 0.6 mg m-3 Chl-a, 28 - 28.5 0C SST in Western and 0.25 - 0.3 mg m-3 Chl-a and 28.5 - 28.80C SST in Eastern were found as highly correlated predictor variables value ranges with SKPJ abundance. The deviances explained in above areas in GAM were 90.8% and 61.4% respectively. The GAM was considered as a robustly dealing method with nonlinear relationships and it can be used to model the fish catch abundance with influencing variables significantly since it could predict the CPUE values greater than 90% similarly to nominal CPUEs in both subregions of the study area.

scholarly journals Evaluation of the Performance of CMIP6 Models in Reproducing Rainfall Patterns over North Africa

Atmosphere ◽  
2021 ◽  
Vol 12 (4) ◽  
pp. 475
Author(s):  
Hassen Babaousmail ◽  
Rongtao Hou ◽  
Brian Ayugi ◽  
Moses Ojara ◽  
Hamida Ngoma ◽  
...  
Keyword(s):  
North Africa ◽  
Rainfall Variability ◽  
Coupled Model ◽  
Cumulative Distribution ◽  
Climatic Research Unit ◽  
Model Ensemble ◽  
Empirical Cumulative Distribution Function ◽  
Cycle Simulation ◽  
Taylor Diagram ◽  
Statistical Metrics

This study assesses the performance of historical rainfall data from the Coupled Model Intercomparison Project phase 6 (CMIP6) in reproducing the spatial and temporal rainfall variability over North Africa. Datasets from Climatic Research Unit (CRU) and Global Precipitation Climatology Centre (GPCC) are used as proxy to observational datasets to examine the capability of 15 CMIP6 models’ and their ensemble in simulating rainfall during 1951–2014. In addition, robust statistical metrics, empirical cumulative distribution function (ECDF), Taylor diagram (TD), and Taylor skill score (TSS) are utilized to assess models’ performance in reproducing annual and seasonal and monthly rainfall over the study domain. Results show that CMIP6 models satisfactorily reproduce mean annual climatology of dry/wet months. However, some models show a slight over/under estimation across dry/wet months. The models’ overall top ranking from all the performance analyses ranging from mean cycle simulation, trend analysis, inter-annual variability, ECDFs, and statistical metrics are as follows: EC-Earth3-Veg, UKESM1-0-LL, GFDL-CM4, NorESM2-LM, IPSL-CM6A-LR, and GFDL-ESM4. The mean model ensemble outperformed the individual CMIP6 models resulting in a TSS ratio (0.79). For future impact studies over the study domain, it is advisable to employ the multi-model ensemble of the best performing models.

scholarly journals presence of whale sharks based on oceanographic variations in Cenderawasih Bay National Park, Papua, Indonesia

2021 ◽  
Vol 22 (11) ◽  
Author(s):  
JAFRY FERDINAN Manuhutu ◽  
DEWA GEDE RAKA WIADNYA ◽  
ABU BAKAR SAMBAH ◽  
ENDANG YULI HERAWATI
Keyword(s):  
National Park ◽  
Additive Model ◽  
Environmental Parameters ◽  
Analysis Data ◽  
Current Speed ◽  
Habitat Modeling ◽  
Sea Surface ◽  
Observation Data ◽  
Whale Shark ◽  
Whale Sharks

Abstract. Manuhutu JF, Wiadnya DGR, Sambah AB, Herawati EY. 2021. The presence of whale sharks based on oceanographic variations in Cenderawasih Bay National Park, Papua, Indonesia. Biodiversitas 22: 4948-4955. Oceanographic factors have an important role in the study of estimating the distribution of fish resource habitats. Sea Surface Temperature (SST), Sea Surface Chlorophyll (SSC), Current Speed, Sea Surface Height (SSH), and bathymetry are important parameters that have been used in estimating the habitat of certain species. Through analyzing these environmental factors, research on the appearance and distribution of whale shark habitats in the Cenderawasih Bay National Park in Papua, Indonesia, utilized field observation data and satellite imagery. This study applied data on the presence of whale sharks and oceanographic parameter data from satellite recordings during 2019 – 2020. Analysis of the relationship and habitat modeling between the monthly presence of whale sharks and environmental parameters was carried out through the Generalized Additive Model (GAM) statistical approach and spatial analysis through the Geographic Information System approach. In the GAM analysis, data on the presence of whale sharks was used as a response variable. In contrast, the predictor variables consisted of SST, SSC, current speed, SSH, and bathymetric data. The results showed that the highest frequency of whale shark presence occurred in the transitional monsoon, with an average presence of 31.77 ± 4.00 %. The study also showed that all predictors showed a highly significant relationship (P < 0.001) to the number of whale sharks present. SST values range from 30.3 – 31.3 °C, SSC of 0.39 – 0.86 mg/L, the current speed of 0.46 – 0.65 m/s, SSH showed 0.63 to 1.00 cm, and bathymetry between 40 – 50 m . In the GAM model, the SST and SSC parameters were the two most important parameters that affect the presence of whale sharks, followed by SSHD, depth (bathymetry), and current parameters.

scholarly journals Optimization of Rain Gauge Networks for Arid Regions Based on Remote Sensing Data

2021 ◽  
Vol 13 (21) ◽  
pp. 4243
Author(s):  
Mona Morsy ◽  
Ruhollah Taghizadeh-Mehrjardi ◽  
Silas Michaelides ◽  
Thomas Scholten ◽  
Peter Dietrich ◽  
...  
Keyword(s):  
Arid Regions ◽  
Flash Flood ◽  
Primary Source ◽  
Remote Sensing Data ◽  
Test Site ◽  
Rain Gauge ◽  
Cumulative Distribution ◽  
Climatic Data ◽  
Empirical Cumulative Distribution Function ◽  
Rain Gauges

Water depletion is a growing problem in the world’s arid and semi-arid areas, where groundwater is the primary source of fresh water. Accurate climatic data must be obtained to protect municipal water budgets. Unfortunately, the majority of these arid regions have a sparsely distributed number of rain gauges, which reduces the reliability of the spatio-temporal fields generated. The current research proposes a series of measures to address the problem of data scarcity, in particular regarding in-situ measurements of precipitation. Once the issue of improving the network of ground precipitation measurements is settled, this may pave the way for much-needed hydrological research on topics such as the spatiotemporal distribution of precipitation, flash flood prevention, and soil erosion reduction. In this study, a k-means cluster analysis is used to determine new locations for the rain gauge network at the Eastern side of the Gulf of Suez in Sinai. The clustering procedure adopted is based on integrating a digital elevation model obtained from The Shuttle Radar Topography Mission (SRTM 90 × 90 m) and Integrated Multi-Satellite Retrievals for GPM (IMERG) for four rainy events. This procedure enabled the determination of the potential centroids for three different cluster sizes (3, 6, and 9). Subsequently, each number was tested using the Empirical Cumulative Distribution Function (ECDF) in an effort to determine the optimal one. However, all the tested centroids exhibited gaps in covering the whole range of elevations and precipitation of the test site. The nine centroids with the five existing rain gauges were used as a basis to calculate the error kriging. This procedure enabled decreasing the error by increasing the number of the proposed gauges. The resulting points were tested again by ECDF and this confirmed the optimum of thirty-one suggested additional gauges in covering the whole range of elevations and precipitation records at the study site.

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